Adding upstream version 1:7.0.4.upstream/1%7.0.4upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

10 files changed, 4127 insertions, 0 deletions

diff --git a/vcl/skia/README b/vcl/skia/README
new file mode 100644
index 000000000..f1248d90c
--- /dev/null
+++ b/vcl/skia/README
@@ -0,0 +1,35 @@
+This is code for using the Skia library as a drawing library in VCL backends.
+See external/skia for info on the library itself.
+
+Environment variables:
+======================
+
+See README.vars in the toplevel vcl/ directory. Note that many backends do not
+use Skia. E.g. on Linux it is necessary to also use SAL_USE_VCLPLUGIN=gen .
+
+There are also GUI options for controlling whether Skia is enabled.
+
+Skia drawing methods:
+=====================
+
+Skia supports several methods to draw:
+- Raster - CPU-based drawing (here primarily used for debugging)
+- Vulkan - Vulkan-based GPU drawing, this is the default
+
+There are more (OpenGL, Metal on Mac, etc.), but (as of now) they are not supported by VCL.
+
+GrContext sharing:
+==================
+
+We use Skia's sk_app::WindowContext class for creating surfaces for windows, that class
+takes care of the internals. But of offscreen drawing, we need an instance of class
+GrContext. There is sk_app::WindowContext::getGrContext(), but each instance creates
+its own GrContext, and apparently it does not work to mix them. Which means that
+for offscreen drawing we would need to know which window (and only that window)
+the contents will be eventually painted to, which is not possible (it may not even
+be known at the time).
+
+To solve this problem we patch sk_app::WindowContext to create just one GrContext object
+and share it between instances. Additionally, using sk_app::WindowContext::SharedGrContext
+it is possible to share it also for offscreen drawing, including keeping proper reference
+count.
diff --git a/vcl/skia/SkiaHelper.cxx b/vcl/skia/SkiaHelper.cxx
new file mode 100644
index 000000000..343ebc284
--- /dev/null
+++ b/vcl/skia/SkiaHelper.cxx
@@ -0,0 +1,611 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/*
+ * This file is part of the LibreOffice project.
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ */
+
+#include <vcl/skia/SkiaHelper.hxx>
+
+#if !HAVE_FEATURE_SKIA
+
+namespace SkiaHelper
+{
+bool isVCLSkiaEnabled() { return false; }
+
+} // namespace
+
+#else
+
+#include <rtl/bootstrap.hxx>
+#include <vcl/svapp.hxx>
+#include <desktop/crashreport.hxx>
+#include <officecfg/Office/Common.hxx>
+#include <watchdog.hxx>
+#include <skia/zone.hxx>
+#include <sal/log.hxx>
+#include <driverblocklist.hxx>
+#include <skia/utils.hxx>
+#include <config_folders.h>
+#include <osl/file.hxx>
+#include <tools/stream.hxx>
+#include <list>
+
+#include <SkCanvas.h>
+#include <SkPaint.h>
+#include <SkSurface.h>
+#include <SkGraphics.h>
+#include <skia_compiler.hxx>
+
+#ifdef DBG_UTIL
+#include <fstream>
+#endif
+
+namespace SkiaHelper
+{
+static OUString getBlacklistFile()
+{
+    OUString url("$BRAND_BASE_DIR/" LIBO_SHARE_FOLDER);
+    rtl::Bootstrap::expandMacros(url);
+
+    return url + "/skia/skia_blacklist_vulkan.xml";
+}
+
+static uint32_t driverVersion = 0;
+uint32_t vendorId = 0;
+
+static OUString versionAsString(uint32_t version)
+{
+    return OUString::number(version >> 22) + "." + OUString::number((version >> 12) & 0x3ff) + "."
+           + OUString::number(version & 0xfff);
+}
+
+static OUStringLiteral vendorAsString(uint32_t vendor)
+{
+    return DriverBlocklist::GetVendorNameFromId(vendor);
+}
+
+static OUString getCacheFolder()
+{
+    OUString url("${$BRAND_BASE_DIR/" LIBO_ETC_FOLDER
+                 "/" SAL_CONFIGFILE("bootstrap") ":UserInstallation}/cache/");
+    rtl::Bootstrap::expandMacros(url);
+    osl::Directory::create(url);
+    return url;
+}
+
+static void writeToLog(SvStream& stream, const char* key, const char* value)
+{
+    stream.WriteCharPtr(key);
+    stream.WriteCharPtr(": ");
+    stream.WriteCharPtr(value);
+    stream.WriteChar('\n');
+}
+
+static void writeToLog(SvStream& stream, const char* key, const OUString& value)
+{
+    writeToLog(stream, key, OUStringToOString(value, RTL_TEXTENCODING_UTF8).getStr());
+}
+
+// Note that this function also logs system information about Vulkan.
+static bool isVulkanBlacklisted(const VkPhysicalDeviceProperties& props)
+{
+    static const char* const types[]
+        = { "other", "integrated", "discrete", "virtual", "cpu", "??" }; // VkPhysicalDeviceType
+    driverVersion = props.driverVersion;
+    vendorId = props.vendorID;
+    OUString vendorIdStr = "0x" + OUString::number(props.vendorID, 16);
+    OUString deviceIdStr = "0x" + OUString::number(props.deviceID, 16);
+    OUString driverVersionString = versionAsString(driverVersion);
+    OUString apiVersion = versionAsString(props.apiVersion);
+    const char* deviceType = types[std::min<unsigned>(props.deviceType, SAL_N_ELEMENTS(types) - 1)];
+
+    CrashReporter::addKeyValue("VulkanVendor", vendorIdStr, CrashReporter::AddItem);
+    CrashReporter::addKeyValue("VulkanDevice", deviceIdStr, CrashReporter::AddItem);
+    CrashReporter::addKeyValue("VulkanAPI", apiVersion, CrashReporter::AddItem);
+    CrashReporter::addKeyValue("VulkanDriver", driverVersionString, CrashReporter::AddItem);
+    CrashReporter::addKeyValue("VulkanDeviceType", OUString::createFromAscii(deviceType),
+                               CrashReporter::AddItem);
+    CrashReporter::addKeyValue("VulkanDeviceName", OUString::createFromAscii(props.deviceName),
+                               CrashReporter::Write);
+
+    SvFileStream logFile(getCacheFolder() + "/skia.log", StreamMode::WRITE | StreamMode::TRUNC);
+    writeToLog(logFile, "RenderMethod", "vulkan");
+    writeToLog(logFile, "Vendor", vendorIdStr);
+    writeToLog(logFile, "Device", deviceIdStr);
+    writeToLog(logFile, "API", apiVersion);
+    writeToLog(logFile, "Driver", driverVersionString);
+    writeToLog(logFile, "DeviceType", deviceType);
+    writeToLog(logFile, "DeviceName", props.deviceName);
+
+    SAL_INFO("vcl.skia",
+             "Vulkan API version: " << apiVersion << ", driver version: " << driverVersionString
+                                    << ", vendor: " << vendorIdStr << " ("
+                                    << vendorAsString(vendorId) << "), device: " << deviceIdStr
+                                    << ", type: " << deviceType << ", name: " << props.deviceName);
+    bool blacklisted
+        = DriverBlocklist::IsDeviceBlocked(getBlacklistFile(), DriverBlocklist::VersionType::Vulkan,
+                                           driverVersionString, vendorIdStr, deviceIdStr);
+    writeToLog(logFile, "Blacklisted", blacklisted ? "yes" : "no");
+    return blacklisted;
+}
+
+static void writeSkiaRasterInfo()
+{
+    SvFileStream logFile(getCacheFolder() + "/skia.log", StreamMode::WRITE | StreamMode::TRUNC);
+    writeToLog(logFile, "RenderMethod", "raster");
+    // Log compiler, Skia works best when compiled with Clang.
+    writeToLog(logFile, "Compiler", skia_compiler_name());
+}
+
+static sk_app::VulkanWindowContext::SharedGrContext getTemporaryGrContext();
+
+static void checkDeviceBlacklisted(bool blockDisable = false)
+{
+    static bool done = false;
+    if (!done)
+    {
+        SkiaZone zone;
+
+        switch (renderMethodToUse())
+        {
+            case RenderVulkan:
+            {
+                // First try if a GrContext already exists.
+                sk_app::VulkanWindowContext::SharedGrContext grContext
+                    = sk_app::VulkanWindowContext::getSharedGrContext();
+                if (!grContext.getGrContext())
+                {
+                    // This function is called from isVclSkiaEnabled(), which
+                    // may be called when deciding which X11 visual to use,
+                    // and that visual is normally needed when creating
+                    // Skia's VulkanWindowContext, which is needed for the GrContext.
+                    // Avoid the loop by creating a temporary GrContext
+                    // that will use the default X11 visual (that shouldn't matter
+                    // for just finding out information about Vulkan) and destroying
+                    // the temporary context will clean up again.
+                    grContext = getTemporaryGrContext();
+                }
+                bool blacklisted = true; // assume the worst
+                if (grContext.getGrContext()) // Vulkan was initialized properly
+                {
+                    blacklisted = isVulkanBlacklisted(
+                        sk_app::VulkanWindowContext::getPhysDeviceProperties());
+                    SAL_INFO("vcl.skia", "Vulkan blacklisted: " << blacklisted);
+                }
+                else
+                    SAL_INFO("vcl.skia", "Vulkan could not be initialized");
+                if (blacklisted && !blockDisable)
+                {
+                    disableRenderMethod(RenderVulkan);
+                    writeSkiaRasterInfo();
+                }
+                break;
+            }
+            case RenderRaster:
+                SAL_INFO("vcl.skia", "Using Skia raster mode");
+                writeSkiaRasterInfo();
+                return; // software, never blacklisted
+        }
+        done = true;
+    }
+}
+
+static bool skiaSupportedByBackend = false;
+static bool supportsVCLSkia()
+{
+    if (!skiaSupportedByBackend)
+    {
+        SAL_INFO("vcl.skia", "Skia not supported by VCL backend, disabling");
+        return false;
+    }
+    return getenv("SAL_DISABLESKIA") == nullptr;
+}
+
+bool isVCLSkiaEnabled()
+{
+    /**
+     * The !bSet part should only be called once! Changing the results in the same
+     * run will mix Skia and normal rendering.
+     */
+
+    static bool bSet = false;
+    static bool bEnable = false;
+    static bool bForceSkia = false;
+
+    // No hardware rendering, so no Skia
+    // TODO SKIA
+    if (Application::IsBitmapRendering())
+        return false;
+
+    if (bSet)
+    {
+        return bForceSkia || bEnable;
+    }
+
+    /*
+     * There are a number of cases that these environment variables cover:
+     *  * SAL_FORCESKIA forces Skia if disabled by UI options or blacklisted
+     *  * SAL_DISABLESKIA avoids the use of Skia regardless of any option
+     */
+
+    bSet = true;
+    bForceSkia = !!getenv("SAL_FORCESKIA") || officecfg::Office::Common::VCL::ForceSkia::get();
+
+    bool bRet = false;
+    bool bSupportsVCLSkia = supportsVCLSkia();
+    if (bForceSkia && bSupportsVCLSkia)
+    {
+        bRet = true;
+        SkGraphics::Init();
+        // don't actually block if blacklisted, but log it if enabled, and also get the vendor id
+        checkDeviceBlacklisted(true);
+    }
+    else if (getenv("SAL_FORCEGL"))
+    {
+        // Skia usage is checked before GL usage, so if GL is forced (and Skia is not), do not
+        // enable Skia in order to allow GL.
+        bRet = false;
+    }
+    else if (bSupportsVCLSkia)
+    {
+        static bool bEnableSkiaEnv = !!getenv("SAL_ENABLESKIA");
+
+        bEnable = bEnableSkiaEnv;
+
+        if (officecfg::Office::Common::VCL::UseSkia::get())
+            bEnable = true;
+
+        // Force disable in safe mode
+        if (Application::IsSafeModeEnabled())
+            bEnable = false;
+
+        if (bEnable)
+        {
+            SkGraphics::Init();
+            checkDeviceBlacklisted(); // switch to raster if driver is blacklisted
+        }
+
+        bRet = bEnable;
+    }
+
+    if (bRet)
+        WatchdogThread::start();
+
+    CrashReporter::addKeyValue("UseSkia", OUString::boolean(bRet), CrashReporter::Write);
+
+    return bRet;
+}
+
+static RenderMethod methodToUse = RenderRaster;
+
+static bool initRenderMethodToUse()
+{
+    if (const char* env = getenv("SAL_SKIA"))
+    {
+        if (strcmp(env, "raster") == 0)
+        {
+            methodToUse = RenderRaster;
+            return true;
+        }
+        if (strcmp(env, "vulkan") == 0)
+        {
+            methodToUse = RenderVulkan;
+            return true;
+        }
+        SAL_WARN("vcl.skia", "Unrecognized value of SAL_SKIA");
+        abort();
+    }
+    if (officecfg::Office::Common::VCL::ForceSkiaRaster::get())
+    {
+        methodToUse = RenderRaster;
+        return true;
+    }
+    methodToUse = RenderVulkan;
+    return true;
+}
+
+RenderMethod renderMethodToUse()
+{
+    static bool methodToUseInited = initRenderMethodToUse();
+    if (methodToUseInited) // Used just to ensure thread-safe one-time init.
+        return methodToUse;
+    abort();
+}
+
+void disableRenderMethod(RenderMethod method)
+{
+    if (renderMethodToUse() != method)
+        return;
+    // Choose a fallback, right now always raster.
+    methodToUse = RenderRaster;
+}
+
+static sk_app::VulkanWindowContext::SharedGrContext* sharedGrContext;
+
+static std::unique_ptr<sk_app::WindowContext> (*createVulkanWindowContextFunction)(bool) = nullptr;
+static void setCreateVulkanWindowContext(std::unique_ptr<sk_app::WindowContext> (*function)(bool))
+{
+    createVulkanWindowContextFunction = function;
+}
+
+GrContext* getSharedGrContext()
+{
+    SkiaZone zone;
+    assert(renderMethodToUse() == RenderVulkan);
+    if (sharedGrContext)
+        return sharedGrContext->getGrContext();
+    // TODO mutex?
+    // Set up the shared GrContext from Skia's (patched) VulkanWindowContext, if it's been
+    // already set up.
+    sk_app::VulkanWindowContext::SharedGrContext context
+        = sk_app::VulkanWindowContext::getSharedGrContext();
+    GrContext* grContext = context.getGrContext();
+    if (grContext)
+    {
+        sharedGrContext = new sk_app::VulkanWindowContext::SharedGrContext(context);
+        return grContext;
+    }
+    static bool done = false;
+    if (done)
+        return nullptr;
+    done = true;
+    if (createVulkanWindowContextFunction == nullptr)
+        return nullptr; // not initialized properly (e.g. used from a VCL backend with no Skia support)
+    std::unique_ptr<sk_app::WindowContext> tmpContext = createVulkanWindowContextFunction(false);
+    // Set up using the shared context created by the call above, if successful.
+    context = sk_app::VulkanWindowContext::getSharedGrContext();
+    grContext = context.getGrContext();
+    if (grContext)
+    {
+        sharedGrContext = new sk_app::VulkanWindowContext::SharedGrContext(context);
+        return grContext;
+    }
+    disableRenderMethod(RenderVulkan);
+    return nullptr;
+}
+
+static sk_app::VulkanWindowContext::SharedGrContext getTemporaryGrContext()
+{
+    if (createVulkanWindowContextFunction == nullptr)
+        return sk_app::VulkanWindowContext::SharedGrContext();
+    std::unique_ptr<sk_app::WindowContext> tmpContext = createVulkanWindowContextFunction(true);
+    // Set up using the shared context created by the call above, if successful.
+    return sk_app::VulkanWindowContext::getSharedGrContext();
+}
+
+sk_sp<SkSurface> createSkSurface(int width, int height, SkColorType type)
+{
+    SkiaZone zone;
+    assert(type == kN32_SkColorType || type == kAlpha_8_SkColorType);
+    sk_sp<SkSurface> surface;
+    switch (SkiaHelper::renderMethodToUse())
+    {
+        case SkiaHelper::RenderVulkan:
+        {
+            if (GrContext* grContext = getSharedGrContext())
+            {
+                surface = SkSurface::MakeRenderTarget(
+                    grContext, SkBudgeted::kNo,
+                    SkImageInfo::Make(width, height, type, kPremul_SkAlphaType));
+                if (surface)
+                {
+#ifdef DBG_UTIL
+                    prefillSurface(surface);
+#endif
+                    return surface;
+                }
+                SAL_WARN("vcl.skia",
+                         "cannot create Vulkan GPU offscreen surface, falling back to Raster");
+            }
+            break;
+        }
+        default:
+            break;
+    }
+    // Create raster surface as a fallback.
+    surface = SkSurface::MakeRaster(SkImageInfo::Make(width, height, type, kPremul_SkAlphaType));
+    assert(surface);
+    if (surface)
+    {
+#ifdef DBG_UTIL
+        prefillSurface(surface);
+#endif
+        return surface;
+    }
+    // In non-debug builds we could return SkSurface::MakeNull() and try to cope with the situation,
+    // but that can lead to unnoticed data loss, so better fail clearly.
+    abort();
+}
+
+sk_sp<SkImage> createSkImage(const SkBitmap& bitmap)
+{
+    SkiaZone zone;
+    assert(bitmap.colorType() == kN32_SkColorType || bitmap.colorType() == kAlpha_8_SkColorType);
+    switch (SkiaHelper::renderMethodToUse())
+    {
+        case SkiaHelper::RenderVulkan:
+        {
+            if (GrContext* grContext = getSharedGrContext())
+            {
+                sk_sp<SkSurface> surface = SkSurface::MakeRenderTarget(
+                    grContext, SkBudgeted::kNo, bitmap.info().makeAlphaType(kPremul_SkAlphaType));
+                if (surface)
+                {
+                    SkPaint paint;
+                    paint.setBlendMode(SkBlendMode::kSrc); // set as is, including alpha
+                    surface->getCanvas()->drawBitmap(bitmap, 0, 0, &paint);
+                    return makeCheckedImageSnapshot(surface);
+                }
+                // Try to fall back in non-debug builds.
+                SAL_WARN("vcl.skia",
+                         "cannot create Vulkan GPU offscreen surface, falling back to Raster");
+            }
+            break;
+        }
+        default:
+            break;
+    }
+    // Create raster image as a fallback.
+    sk_sp<SkImage> image = SkImage::MakeFromBitmap(bitmap);
+    assert(image);
+    return image;
+}
+
+sk_sp<SkImage> makeCheckedImageSnapshot(sk_sp<SkSurface> surface)
+{
+    sk_sp<SkImage> ret = surface->makeImageSnapshot();
+    assert(ret);
+    if (ret)
+        return ret;
+    abort();
+}
+
+sk_sp<SkImage> makeCheckedImageSnapshot(sk_sp<SkSurface> surface, const SkIRect& bounds)
+{
+    sk_sp<SkImage> ret = surface->makeImageSnapshot(bounds);
+    assert(ret);
+    if (ret)
+        return ret;
+    abort();
+}
+
+namespace
+{
+// Image cache, for saving results of complex operations such as drawTransformedBitmap().
+struct ImageCacheItem
+{
+    OString key;
+    sk_sp<SkImage> image;
+    int size; // cost of the item
+};
+} //namespace
+
+// LRU cache, last item is the least recently used. Hopefully there won't be that many items
+// to require a hash/map. Using o3tl::lru_cache would be simpler, but it doesn't support
+// calculating cost of each item.
+static std::list<ImageCacheItem>* imageCache = nullptr;
+static int imageCacheSize = 0; // sum of all ImageCacheItem.size
+
+void addCachedImage(const OString& key, sk_sp<SkImage> image)
+{
+    static bool disabled = getenv("SAL_DISABLE_SKIA_CACHE") != nullptr;
+    if (disabled)
+        return;
+    if (imageCache == nullptr)
+        imageCache = new std::list<ImageCacheItem>;
+    int size = image->width() * image->height()
+               * SkColorTypeBytesPerPixel(image->imageInfo().colorType());
+    imageCache->push_front({ key, image, size });
+    imageCacheSize += size;
+    SAL_INFO("vcl.skia.trace", "addcachedimage " << image << " :" << size << "/" << imageCacheSize);
+    const int MAX_CACHE_SIZE = 4 * 1000 * 1000 * 4; // 4x 1000px 32bpp images, 16MiB
+    while (imageCacheSize > MAX_CACHE_SIZE)
+    {
+        assert(!imageCache->empty());
+        imageCacheSize -= imageCache->back().size;
+        SAL_INFO("vcl.skia.trace",
+                 "least used removal " << image << ":" << imageCache->back().size);
+        imageCache->pop_back();
+    }
+}
+
+sk_sp<SkImage> findCachedImage(const OString& key)
+{
+    if (imageCache != nullptr)
+    {
+        for (auto it = imageCache->begin(); it != imageCache->end(); ++it)
+        {
+            if (it->key == key)
+            {
+                sk_sp<SkImage> ret = it->image;
+                SAL_INFO("vcl.skia.trace",
+                         "findcachedimage " << key << " : " << it->image << " found");
+                imageCache->splice(imageCache->begin(), *imageCache, it);
+                return ret;
+            }
+        }
+    }
+    SAL_INFO("vcl.skia.trace", "findcachedimage " << key << " not found");
+    return nullptr;
+}
+
+void removeCachedImage(sk_sp<SkImage> image)
+{
+    if (imageCache == nullptr)
+        return;
+    for (auto it = imageCache->begin(); it != imageCache->end();)
+    {
+        if (it->image == image)
+        {
+            imageCacheSize -= it->size;
+            assert(imageCacheSize >= 0);
+            it = imageCache->erase(it);
+        }
+        else
+            ++it;
+    }
+}
+
+void cleanup()
+{
+    delete sharedGrContext;
+    sharedGrContext = nullptr;
+    delete imageCache;
+    imageCache = nullptr;
+    imageCacheSize = 0;
+}
+
+// Skia should not be used from VCL backends that do not actually support it, as there will be setup missing.
+// The code here (that is in the vcl lib) needs a function for creating Vulkan context that is
+// usually available only in the backend libs.
+void prepareSkia(std::unique_ptr<sk_app::WindowContext> (*createVulkanWindowContext)(bool))
+{
+    setCreateVulkanWindowContext(createVulkanWindowContext);
+    skiaSupportedByBackend = true;
+}
+
+#ifdef DBG_UTIL
+void prefillSurface(sk_sp<SkSurface>& surface)
+{
+    // Pre-fill the surface with deterministic garbage.
+    SkBitmap bitmap;
+    bitmap.allocN32Pixels(2, 2);
+    SkPMColor* scanline;
+    scanline = bitmap.getAddr32(0, 0);
+    *scanline++ = SkPreMultiplyARGB(0xFF, 0xBF, 0x80, 0x40);
+    *scanline++ = SkPreMultiplyARGB(0xFF, 0x40, 0x80, 0xBF);
+    scanline = bitmap.getAddr32(0, 1);
+    *scanline++ = SkPreMultiplyARGB(0xFF, 0xE3, 0x5C, 0x13);
+    *scanline++ = SkPreMultiplyARGB(0xFF, 0x13, 0x5C, 0xE3);
+    bitmap.setImmutable();
+    SkPaint paint;
+    paint.setBlendMode(SkBlendMode::kSrc); // set as is, including alpha
+    paint.setShader(bitmap.makeShader(SkTileMode::kRepeat, SkTileMode::kRepeat));
+    surface->getCanvas()->drawPaint(paint);
+}
+
+void dump(const SkBitmap& bitmap, const char* file) { dump(SkImage::MakeFromBitmap(bitmap), file); }
+
+void dump(const sk_sp<SkSurface>& surface, const char* file)
+{
+    surface->getCanvas()->flush();
+    dump(makeCheckedImageSnapshot(surface), file);
+}
+
+void dump(const sk_sp<SkImage>& image, const char* file)
+{
+    sk_sp<SkData> data = image->encodeToData();
+    std::ofstream ostream(file, std::ios::binary);
+    ostream.write(static_cast<const char*>(data->data()), data->size());
+}
+
+#endif
+
+} // namespace
+
+#endif // HAVE_FEATURE_SKIA
+
+/* vim:set shiftwidth=4 softtabstop=4 expandtab: */
diff --git a/vcl/skia/gdiimpl.cxx b/vcl/skia/gdiimpl.cxx
new file mode 100644
index 000000000..bd497d7f8
--- /dev/null
+++ b/vcl/skia/gdiimpl.cxx
@@ -0,0 +1,1829 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/*
+ * This file is part of the LibreOffice project.
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ *
+ * This file incorporates work covered by the following license notice:
+ *
+ *   Licensed to the Apache Software Foundation (ASF) under one or more
+ *   contributor license agreements. See the NOTICE file distributed
+ *   with this work for additional information regarding copyright
+ *   ownership. The ASF licenses this file to you under the Apache
+ *   License, Version 2.0 (the "License"); you may not use this file
+ *   except in compliance with the License. You may obtain a copy of
+ *   the License at http://www.apache.org/licenses/LICENSE-2.0 .
+ */
+
+#include <skia/gdiimpl.hxx>
+
+#include <salgdi.hxx>
+#include <skia/salbmp.hxx>
+#include <vcl/idle.hxx>
+#include <vcl/svapp.hxx>
+#include <vcl/lazydelete.hxx>
+#include <vcl/skia/SkiaHelper.hxx>
+#include <skia/utils.hxx>
+#include <skia/zone.hxx>
+
+#include <SkCanvas.h>
+#include <SkPath.h>
+#include <SkRegion.h>
+#include <SkDashPathEffect.h>
+#include <GrBackendSurface.h>
+#include <SkTextBlob.h>
+#include <SkRSXform.h>
+
+#include <numeric>
+#include <basegfx/polygon/b2dpolygontools.hxx>
+#include <basegfx/polygon/b2dpolypolygontools.hxx>
+#include <basegfx/polygon/b2dpolypolygoncutter.hxx>
+#include <o3tl/sorted_vector.hxx>
+
+namespace
+{
+// Create Skia Path from B2DPolygon
+// Note that polygons generally have the complication that when used
+// for area (fill) operations they usually miss the right-most and
+// bottom-most line of pixels of the bounding rectangle (see
+// https://lists.freedesktop.org/archives/libreoffice/2019-November/083709.html).
+// So be careful with rectangle->polygon conversions (generally avoid them).
+void addPolygonToPath(const basegfx::B2DPolygon& rPolygon, SkPath& rPath,
+                      bool* hasOnlyOrthogonal = nullptr)
+{
+    const sal_uInt32 nPointCount(rPolygon.count());
+
+    if (nPointCount <= 1)
+        return;
+
+    const bool bClosePath(rPolygon.isClosed());
+    const bool bHasCurves(rPolygon.areControlPointsUsed());
+
+    bool bFirst = true;
+
+    sal_uInt32 nCurrentIndex = 0;
+    sal_uInt32 nPreviousIndex = nPointCount - 1;
+
+    basegfx::B2DPoint aCurrentPoint;
+    basegfx::B2DPoint aPreviousPoint;
+
+    for (sal_uInt32 nIndex = 0; nIndex <= nPointCount; nIndex++)
+    {
+        if (nIndex == nPointCount && !bClosePath)
+            continue;
+
+        // Make sure we loop the last point to first point
+        nCurrentIndex = nIndex % nPointCount;
+        aCurrentPoint = rPolygon.getB2DPoint(nCurrentIndex);
+
+        if (bFirst)
+        {
+            rPath.moveTo(aCurrentPoint.getX(), aCurrentPoint.getY());
+            bFirst = false;
+        }
+        else if (!bHasCurves)
+        {
+            rPath.lineTo(aCurrentPoint.getX(), aCurrentPoint.getY());
+            // If asked for, check whether the polygon has a line that is not
+            // strictly horizontal or vertical.
+            if (hasOnlyOrthogonal != nullptr && aCurrentPoint.getX() != aPreviousPoint.getX()
+                && aCurrentPoint.getY() != aPreviousPoint.getY())
+                *hasOnlyOrthogonal = false;
+        }
+        else
+        {
+            basegfx::B2DPoint aPreviousControlPoint = rPolygon.getNextControlPoint(nPreviousIndex);
+            basegfx::B2DPoint aCurrentControlPoint = rPolygon.getPrevControlPoint(nCurrentIndex);
+
+            if (aPreviousControlPoint.equal(aPreviousPoint))
+            {
+                aPreviousControlPoint
+                    = aPreviousPoint + ((aPreviousControlPoint - aCurrentPoint) * 0.0005);
+            }
+
+            if (aCurrentControlPoint.equal(aCurrentPoint))
+            {
+                aCurrentControlPoint
+                    = aCurrentPoint + ((aCurrentControlPoint - aPreviousPoint) * 0.0005);
+            }
+            rPath.cubicTo(aPreviousControlPoint.getX(), aPreviousControlPoint.getY(),
+                          aCurrentControlPoint.getX(), aCurrentControlPoint.getY(),
+                          aCurrentPoint.getX(), aCurrentPoint.getY());
+            if (hasOnlyOrthogonal != nullptr)
+                *hasOnlyOrthogonal = false;
+        }
+        aPreviousPoint = aCurrentPoint;
+        nPreviousIndex = nCurrentIndex;
+    }
+    if (bClosePath)
+    {
+        rPath.close();
+    }
+}
+
+void addPolyPolygonToPath(const basegfx::B2DPolyPolygon& rPolyPolygon, SkPath& rPath,
+                          bool* hasOnlyOrthogonal = nullptr)
+{
+    const sal_uInt32 nPolygonCount(rPolyPolygon.count());
+
+    if (nPolygonCount == 0)
+        return;
+
+    for (const auto& rPolygon : rPolyPolygon)
+    {
+        addPolygonToPath(rPolygon, rPath, hasOnlyOrthogonal);
+    }
+}
+
+// Check if the given polygon contains a straight line. If not, it consists
+// solely of curves.
+bool polygonContainsLine(const basegfx::B2DPolyPolygon& rPolyPolygon)
+{
+    if (!rPolyPolygon.areControlPointsUsed())
+        return true; // no curves at all
+    for (const auto& rPolygon : rPolyPolygon)
+    {
+        const sal_uInt32 nPointCount(rPolygon.count());
+        bool bFirst = true;
+
+        const bool bClosePath(rPolygon.isClosed());
+
+        sal_uInt32 nCurrentIndex = 0;
+        sal_uInt32 nPreviousIndex = nPointCount - 1;
+
+        basegfx::B2DPoint aCurrentPoint;
+        basegfx::B2DPoint aPreviousPoint;
+
+        for (sal_uInt32 nIndex = 0; nIndex <= nPointCount; nIndex++)
+        {
+            if (nIndex == nPointCount && !bClosePath)
+                continue;
+
+            // Make sure we loop the last point to first point
+            nCurrentIndex = nIndex % nPointCount;
+            if (bFirst)
+                bFirst = false;
+            else
+            {
+                basegfx::B2DPoint aPreviousControlPoint
+                    = rPolygon.getNextControlPoint(nPreviousIndex);
+                basegfx::B2DPoint aCurrentControlPoint
+                    = rPolygon.getPrevControlPoint(nCurrentIndex);
+
+                if (aPreviousControlPoint.equal(aPreviousPoint)
+                    && aCurrentControlPoint.equal(aCurrentPoint))
+                {
+                    return true; // found a straight line
+                }
+            }
+            aPreviousPoint = aCurrentPoint;
+            nPreviousIndex = nCurrentIndex;
+        }
+    }
+    return false; // no straight line found
+}
+
+SkColor toSkColor(Color color)
+{
+    return SkColorSetARGB(255 - color.GetTransparency(), color.GetRed(), color.GetGreen(),
+                          color.GetBlue());
+}
+
+SkColor toSkColorWithTransparency(Color aColor, double fTransparency)
+{
+    return SkColorSetA(toSkColor(aColor), 255 * (1.0 - fTransparency));
+}
+
+Color fromSkColor(SkColor color)
+{
+    return Color(255 - SkColorGetA(color), SkColorGetR(color), SkColorGetG(color),
+                 SkColorGetB(color));
+}
+
+// returns true if the source or destination rectangles are invalid
+bool checkInvalidSourceOrDestination(SalTwoRect const& rPosAry)
+{
+    return rPosAry.mnSrcWidth <= 0 || rPosAry.mnSrcHeight <= 0 || rPosAry.mnDestWidth <= 0
+           || rPosAry.mnDestHeight <= 0;
+}
+
+} // end anonymous namespace
+
+// Class that triggers flushing the backing buffer when idle.
+class SkiaFlushIdle : public Idle
+{
+    SkiaSalGraphicsImpl* mpGraphics;
+#ifndef NDEBUG
+    char* debugname;
+#endif
+
+public:
+    explicit SkiaFlushIdle(SkiaSalGraphicsImpl* pGraphics)
+        : Idle(get_debug_name(pGraphics))
+        , mpGraphics(pGraphics)
+    {
+        // We don't want to be swapping before we've painted.
+        SetPriority(TaskPriority::POST_PAINT);
+    }
+#ifndef NDEBUG
+    virtual ~SkiaFlushIdle() { free(debugname); }
+    const char* get_debug_name(SkiaSalGraphicsImpl* pGraphics)
+    {
+        // Idle keeps just a pointer, so we need to store the string
+        debugname = strdup(
+            OString("skia idle 0x" + OString::number(reinterpret_cast<sal_uIntPtr>(pGraphics), 16))
+                .getStr());
+        return debugname;
+    }
+#else
+    const char* get_debug_name(SkiaSalGraphicsImpl*) { return "skia idle"; }
+#endif
+
+    virtual void Invoke() override
+    {
+        mpGraphics->performFlush();
+        Stop();
+        SetPriority(TaskPriority::HIGHEST);
+    }
+};
+
+SkiaSalGraphicsImpl::SkiaSalGraphicsImpl(SalGraphics& rParent, SalGeometryProvider* pProvider)
+    : mParent(rParent)
+    , mProvider(pProvider)
+    , mIsGPU(false)
+    , mLineColor(SALCOLOR_NONE)
+    , mFillColor(SALCOLOR_NONE)
+    , mXorMode(false)
+    , mFlush(new SkiaFlushIdle(this))
+{
+}
+
+SkiaSalGraphicsImpl::~SkiaSalGraphicsImpl()
+{
+    assert(!mSurface);
+    assert(!mWindowContext);
+}
+
+void SkiaSalGraphicsImpl::Init() {}
+
+void SkiaSalGraphicsImpl::createSurface()
+{
+    SkiaZone zone;
+    if (isOffscreen())
+        createOffscreenSurface();
+    else
+        createWindowSurface();
+    mSurface->getCanvas()->save(); // see SetClipRegion()
+    mClipRegion = vcl::Region(tools::Rectangle(0, 0, GetWidth(), GetHeight()));
+
+    // We don't want to be swapping before we've painted.
+    mFlush->Stop();
+    mFlush->SetPriority(TaskPriority::POST_PAINT);
+}
+
+void SkiaSalGraphicsImpl::createWindowSurface(bool forceRaster)
+{
+    SkiaZone zone;
+    assert(!isOffscreen());
+    assert(!mSurface);
+    assert(!mWindowContext);
+    createWindowContext(forceRaster);
+    if (mWindowContext)
+        mSurface = mWindowContext->getBackbufferSurface();
+    if (!mSurface)
+    {
+        switch (SkiaHelper::renderMethodToUse())
+        {
+            case SkiaHelper::RenderVulkan:
+                SAL_WARN("vcl.skia",
+                         "cannot create Vulkan GPU window surface, falling back to Raster");
+                destroySurface(); // destroys also WindowContext
+                return createWindowSurface(true); // try again
+            case SkiaHelper::RenderRaster:
+                abort(); // This should not really happen, do not even try to cope with it.
+        }
+    }
+    mIsGPU = mSurface->getCanvas()->getGrContext() != nullptr;
+#ifdef DBG_UTIL
+    SkiaHelper::prefillSurface(mSurface);
+#endif
+}
+
+void SkiaSalGraphicsImpl::createOffscreenSurface()
+{
+    SkiaZone zone;
+    assert(isOffscreen());
+    assert(!mSurface);
+    assert(!mWindowContext);
+    // When created (especially on Windows), Init() gets called with size (0,0), which is invalid size
+    // for Skia. May happen also in rare cases such as shutting down (tdf#131939).
+    int width = std::max(1, GetWidth());
+    int height = std::max(1, GetHeight());
+    switch (SkiaHelper::renderMethodToUse())
+    {
+        case SkiaHelper::RenderVulkan:
+        {
+            if (SkiaHelper::getSharedGrContext())
+            {
+                mSurface = SkiaHelper::createSkSurface(width, height);
+                if (mSurface)
+                {
+                    mIsGPU = mSurface->getCanvas()->getGrContext() != nullptr;
+                    return;
+                }
+            }
+            break;
+        }
+        default:
+            break;
+    }
+    // Create raster surface as a fallback.
+    mSurface = SkiaHelper::createSkSurface(width, height);
+    assert(mSurface);
+    assert(!mSurface->getCanvas()->getGrContext()); // is not GPU-backed
+    mIsGPU = false;
+}
+
+void SkiaSalGraphicsImpl::destroySurface()
+{
+    SkiaZone zone;
+    if (mSurface)
+    {
+        // check setClipRegion() invariant
+        assert(mSurface->getCanvas()->getSaveCount() == 2);
+        // if this fails, something forgot to use SkAutoCanvasRestore
+        assert(mSurface->getCanvas()->getTotalMatrix().isIdentity());
+    }
+    // If we use e.g. Vulkan, we must destroy the surface before the context,
+    // otherwise destroying the surface will reference the context. This is
+    // handled by calling destroySurface() before destroying the context.
+    // However we also need to flush the surface before destroying it,
+    // otherwise when destroying the context later there still could be queued
+    // commands referring to the surface data. This is probably a Skia bug,
+    // but work around it here.
+    if (mSurface)
+        mSurface->flushAndSubmit();
+    mSurface.reset();
+    mWindowContext.reset();
+    mIsGPU = false;
+}
+
+void SkiaSalGraphicsImpl::DeInit() { destroySurface(); }
+
+void SkiaSalGraphicsImpl::preDraw()
+{
+    assert(comphelper::SolarMutex::get()->IsCurrentThread());
+    SkiaZone::enter(); // matched in postDraw()
+    checkSurface();
+    checkPendingDrawing();
+}
+
+void SkiaSalGraphicsImpl::postDraw()
+{
+    scheduleFlush();
+    SkiaZone::leave(); // matched in preDraw()
+    // If there's a problem with the GPU context, abort.
+    if (GrContext* context = mSurface->getCanvas()->getGrContext())
+    {
+        // Running out of memory on the GPU technically could be possibly recoverable,
+        // but we don't know the exact status of the surface (and what has or has not been drawn to it),
+        // so in practice this is unrecoverable without possible data loss.
+        if (context->oomed())
+        {
+            SAL_WARN("vcl.skia", "GPU context has run out of memory, aborting.");
+            abort();
+        }
+        // Unrecoverable problem.
+        if (context->abandoned())
+        {
+            SAL_WARN("vcl.skia", "GPU context has been abandoned, aborting.");
+            abort();
+        }
+    }
+}
+
+void SkiaSalGraphicsImpl::scheduleFlush()
+{
+    if (!isOffscreen())
+    {
+        if (!Application::IsInExecute())
+            performFlush(); // otherwise nothing would trigger idle rendering
+        else if (!mFlush->IsActive())
+            mFlush->Start();
+    }
+}
+
+// VCL can sometimes resize us without telling us, update the surface if needed.
+// Also create the surface on demand if it has not been created yet (it is a waste
+// to create it in Init() if it gets recreated later anyway).
+void SkiaSalGraphicsImpl::checkSurface()
+{
+    if (!mSurface)
+    {
+        createSurface();
+        SAL_INFO("vcl.skia.trace",
+                 "create(" << this << "): " << Size(mSurface->width(), mSurface->height()));
+    }
+    else if (GetWidth() != mSurface->width() || GetHeight() != mSurface->height())
+    {
+        if (avoidRecreateByResize())
+            return;
+
+        if (!GetWidth() || !GetHeight())
+        {
+            SAL_WARN("vcl.skia", "recreate(" << this << "): can't create empty surface "
+                                             << Size(GetWidth(), GetHeight())
+                                             << " => keeping old one!");
+            return;
+        }
+
+        {
+            Size oldSize(mSurface->width(), mSurface->height());
+            // Recreating a surface means that the old SkSurface contents will be lost.
+            // But if a window has been resized the windowing system may send repaint events
+            // only for changed parts and VCL would not repaint the whole area, assuming
+            // that some parts have not changed (this is what seems to cause tdf#131952).
+            // So carry over the old contents for windows, even though generally everything
+            // will be usually repainted anyway.
+            sk_sp<SkImage> snapshot;
+            if (!isOffscreen())
+            {
+                flushDrawing();
+                snapshot = SkiaHelper::makeCheckedImageSnapshot(mSurface);
+            }
+
+            destroySurface();
+            createSurface();
+
+            if (snapshot)
+            {
+                SkPaint paint;
+                paint.setBlendMode(SkBlendMode::kSrc); // copy as is
+                mSurface->getCanvas()->drawImage(snapshot, 0, 0, &paint);
+            }
+            SAL_INFO("vcl.skia.trace", "recreate(" << this << "): old " << oldSize << " new "
+                                                   << Size(mSurface->width(), mSurface->height())
+                                                   << " requested "
+                                                   << Size(GetWidth(), GetHeight()));
+        }
+    }
+}
+
+void SkiaSalGraphicsImpl::flushDrawing()
+{
+    if (!mSurface)
+        return;
+    checkPendingDrawing();
+    if (mXorMode)
+        applyXor();
+    mSurface->flushAndSubmit();
+}
+
+bool SkiaSalGraphicsImpl::setClipRegion(const vcl::Region& region)
+{
+    if (mClipRegion == region)
+        return true;
+    SkiaZone zone;
+    checkPendingDrawing();
+    checkSurface();
+    mClipRegion = region;
+    SAL_INFO("vcl.skia.trace", "setclipregion(" << this << "): " << region);
+    SkCanvas* canvas = mSurface->getCanvas();
+    // SkCanvas::clipRegion() can only further reduce the clip region,
+    // but we need to set the given region, which may extend it.
+    // So handle that by always having the full clip region saved on the stack
+    // and always go back to that. SkCanvas::restore() only affects the clip
+    // and the matrix.
+    assert(canvas->getSaveCount() == 2); // = there is just one save()
+    canvas->restore();
+    canvas->save();
+    setCanvasClipRegion(canvas, region);
+    return true;
+}
+
+void SkiaSalGraphicsImpl::setCanvasClipRegion(SkCanvas* canvas, const vcl::Region& region)
+{
+    SkiaZone zone;
+    SkPath path;
+    // Always use region rectangles, regardless of what the region uses internally.
+    // That's what other VCL backends do, and trying to use addPolyPolygonToPath()
+    // in case a polygon is used leads to off-by-one errors such as tdf#133208.
+    RectangleVector rectangles;
+    region.GetRegionRectangles(rectangles);
+    for (const tools::Rectangle& rectangle : rectangles)
+        path.addRect(SkRect::MakeXYWH(rectangle.getX(), rectangle.getY(), rectangle.GetWidth(),
+                                      rectangle.GetHeight()));
+    path.setFillType(SkPathFillType::kEvenOdd);
+    canvas->clipPath(path);
+}
+
+void SkiaSalGraphicsImpl::ResetClipRegion()
+{
+    setClipRegion(vcl::Region(tools::Rectangle(0, 0, GetWidth(), GetHeight())));
+}
+
+const vcl::Region& SkiaSalGraphicsImpl::getClipRegion() const { return mClipRegion; }
+
+sal_uInt16 SkiaSalGraphicsImpl::GetBitCount() const { return 32; }
+
+long SkiaSalGraphicsImpl::GetGraphicsWidth() const { return GetWidth(); }
+
+void SkiaSalGraphicsImpl::SetLineColor()
+{
+    checkPendingDrawing();
+    mLineColor = SALCOLOR_NONE;
+}
+
+void SkiaSalGraphicsImpl::SetLineColor(Color nColor)
+{
+    checkPendingDrawing();
+    mLineColor = nColor;
+}
+
+void SkiaSalGraphicsImpl::SetFillColor()
+{
+    checkPendingDrawing();
+    mFillColor = SALCOLOR_NONE;
+}
+
+void SkiaSalGraphicsImpl::SetFillColor(Color nColor)
+{
+    checkPendingDrawing();
+    mFillColor = nColor;
+}
+
+void SkiaSalGraphicsImpl::SetXORMode(bool set, bool)
+{
+    if (mXorMode == set)
+        return;
+    checkPendingDrawing();
+    SAL_INFO("vcl.skia.trace", "setxormode(" << this << "): " << set);
+    if (set)
+        mXorRegion.setEmpty();
+    else
+        applyXor();
+    mXorMode = set;
+}
+
+SkCanvas* SkiaSalGraphicsImpl::getXorCanvas()
+{
+    SkiaZone zone;
+    assert(mXorMode);
+    // Skia does not implement xor drawing, so we need to handle it manually by redirecting
+    // to a temporary SkBitmap and then doing the xor operation on the data ourselves.
+    // There's no point in using SkSurface for GPU, we'd immediately need to get the pixels back.
+    if (!mXorCanvas)
+    {
+        // Use unpremultiplied alpha (see xor applying in applyXor()).
+        if (!mXorBitmap.tryAllocPixels(mSurface->imageInfo().makeAlphaType(kUnpremul_SkAlphaType)))
+            abort();
+        mXorBitmap.eraseARGB(0, 0, 0, 0);
+        mXorCanvas = std::make_unique<SkCanvas>(mXorBitmap);
+        setCanvasClipRegion(mXorCanvas.get(), mClipRegion);
+    }
+    return mXorCanvas.get();
+}
+
+void SkiaSalGraphicsImpl::applyXor()
+{
+    // Apply the result from the temporary bitmap manually. This is indeed
+    // slow, but it doesn't seem to be needed often and is optimized
+    // in each operation by extending mXorRegion with the area that should be
+    // updated.
+    assert(mXorMode);
+    if (!mSurface || !mXorCanvas
+        || !mXorRegion.op(SkIRect::MakeXYWH(0, 0, mSurface->width(), mSurface->height()),
+                          SkRegion::kIntersect_Op))
+    {
+        mXorRegion.setEmpty();
+        return;
+    }
+    SAL_INFO("vcl.skia.trace", "applyxor(" << this << "): " << mXorRegion);
+    // Copy the surface contents to another pixmap.
+    SkBitmap surfaceBitmap;
+    // Use unpremultiplied alpha format, so that we do not have to do the conversions to get
+    // the RGB and back (Skia will do it when converting, but it'll be presumably faster at it).
+    if (!surfaceBitmap.tryAllocPixels(mSurface->imageInfo().makeAlphaType(kUnpremul_SkAlphaType)))
+        abort();
+    SkPaint paint;
+    paint.setBlendMode(SkBlendMode::kSrc); // copy as is
+    SkCanvas canvas(surfaceBitmap);
+    canvas.drawImageRect(SkiaHelper::makeCheckedImageSnapshot(mSurface), mXorRegion.getBounds(),
+                         SkRect::Make(mXorRegion.getBounds()), &paint);
+    // xor to surfaceBitmap
+    assert(surfaceBitmap.info().alphaType() == kUnpremul_SkAlphaType);
+    assert(mXorBitmap.info().alphaType() == kUnpremul_SkAlphaType);
+    assert(surfaceBitmap.bytesPerPixel() == 4);
+    assert(mXorBitmap.bytesPerPixel() == 4);
+    for (SkRegion::Iterator it(mXorRegion); !it.done(); it.next())
+    {
+        for (int y = it.rect().top(); y < it.rect().bottom(); ++y)
+        {
+            uint8_t* data = static_cast<uint8_t*>(surfaceBitmap.getAddr(it.rect().x(), y));
+            const uint8_t* xordata = static_cast<uint8_t*>(mXorBitmap.getAddr(it.rect().x(), y));
+            for (int x = 0; x < it.rect().width(); ++x)
+            {
+                *data++ ^= *xordata++;
+                *data++ ^= *xordata++;
+                *data++ ^= *xordata++;
+                // alpha is not xor-ed
+                data++;
+                xordata++;
+            }
+        }
+    }
+    surfaceBitmap.notifyPixelsChanged();
+    mSurface->getCanvas()->drawBitmapRect(surfaceBitmap, mXorRegion.getBounds(),
+                                          SkRect::Make(mXorRegion.getBounds()), &paint);
+    mXorCanvas.reset();
+    mXorBitmap.reset();
+    mXorRegion.setEmpty();
+}
+
+void SkiaSalGraphicsImpl::SetROPLineColor(SalROPColor nROPColor)
+{
+    checkPendingDrawing();
+    switch (nROPColor)
+    {
+        case SalROPColor::N0:
+            mLineColor = Color(0, 0, 0);
+            break;
+        case SalROPColor::N1:
+            mLineColor = Color(0xff, 0xff, 0xff);
+            break;
+        case SalROPColor::Invert:
+            mLineColor = Color(0xff, 0xff, 0xff);
+            break;
+    }
+}
+
+void SkiaSalGraphicsImpl::SetROPFillColor(SalROPColor nROPColor)
+{
+    checkPendingDrawing();
+    switch (nROPColor)
+    {
+        case SalROPColor::N0:
+            mFillColor = Color(0, 0, 0);
+            break;
+        case SalROPColor::N1:
+            mFillColor = Color(0xff, 0xff, 0xff);
+            break;
+        case SalROPColor::Invert:
+            mFillColor = Color(0xff, 0xff, 0xff);
+            break;
+    }
+}
+
+void SkiaSalGraphicsImpl::drawPixel(long nX, long nY) { drawPixel(nX, nY, mLineColor); }
+
+void SkiaSalGraphicsImpl::drawPixel(long nX, long nY, Color nColor)
+{
+    if (nColor == SALCOLOR_NONE)
+        return;
+    preDraw();
+    SAL_INFO("vcl.skia.trace", "drawpixel(" << this << "): " << Point(nX, nY) << ":" << nColor);
+    addXorRegion(SkRect::MakeXYWH(nX, nY, 1, 1));
+    SkPaint paint;
+    paint.setColor(toSkColor(nColor));
+    // Apparently drawPixel() is actually expected to set the pixel and not draw it.
+    paint.setBlendMode(SkBlendMode::kSrc); // set as is, including alpha
+    getDrawCanvas()->drawPoint(toSkX(nX), toSkY(nY), paint);
+    postDraw();
+}
+
+void SkiaSalGraphicsImpl::drawLine(long nX1, long nY1, long nX2, long nY2)
+{
+    if (mLineColor == SALCOLOR_NONE)
+        return;
+    preDraw();
+    SAL_INFO("vcl.skia.trace", "drawline(" << this << "): " << Point(nX1, nY1) << "->"
+                                           << Point(nX2, nY2) << ":" << mLineColor);
+    addXorRegion(SkRect::MakeLTRB(nX1, nY1, nX2, nY2).makeSorted());
+    SkPaint paint;
+    paint.setColor(toSkColor(mLineColor));
+    paint.setAntiAlias(mParent.getAntiAliasB2DDraw());
+    getDrawCanvas()->drawLine(toSkX(nX1), toSkY(nY1), toSkX(nX2), toSkY(nY2), paint);
+    postDraw();
+}
+
+void SkiaSalGraphicsImpl::privateDrawAlphaRect(long nX, long nY, long nWidth, long nHeight,
+                                               double fTransparency, bool blockAA)
+{
+    preDraw();
+    SAL_INFO("vcl.skia.trace",
+             "privatedrawrect(" << this << "): " << SkIRect::MakeXYWH(nX, nY, nWidth, nHeight)
+                                << ":" << mLineColor << ":" << mFillColor << ":" << fTransparency);
+    addXorRegion(SkRect::MakeXYWH(nX, nY, nWidth, nHeight));
+    SkCanvas* canvas = getDrawCanvas();
+    SkPaint paint;
+    paint.setAntiAlias(!blockAA && mParent.getAntiAliasB2DDraw());
+    if (mFillColor != SALCOLOR_NONE)
+    {
+        paint.setColor(toSkColorWithTransparency(mFillColor, fTransparency));
+        paint.setStyle(SkPaint::kFill_Style);
+        // HACK: If the polygon is just a line, it still should be drawn. But when filling
+        // Skia doesn't draw empty polygons, so in that case ensure the line is drawn.
+        if (mLineColor == SALCOLOR_NONE && SkSize::Make(nWidth, nHeight).isEmpty())
+            paint.setStyle(SkPaint::kStroke_Style);
+        canvas->drawIRect(SkIRect::MakeXYWH(nX, nY, nWidth, nHeight), paint);
+    }
+    if (mLineColor != SALCOLOR_NONE)
+    {
+        paint.setColor(toSkColorWithTransparency(mLineColor, fTransparency));
+        paint.setStyle(SkPaint::kStroke_Style);
+        // The obnoxious "-1 DrawRect()" hack that I don't understand the purpose of (and I'm not sure
+        // if anybody does), but without it some cases do not work. The max() is needed because Skia
+        // will not draw anything if width or height is 0.
+        canvas->drawIRect(
+            SkIRect::MakeXYWH(nX, nY, std::max(1L, nWidth - 1), std::max(1L, nHeight - 1)), paint);
+    }
+    postDraw();
+}
+
+void SkiaSalGraphicsImpl::drawRect(long nX, long nY, long nWidth, long nHeight)
+{
+    privateDrawAlphaRect(nX, nY, nWidth, nHeight, 0.0, true);
+}
+
+void SkiaSalGraphicsImpl::drawPolyLine(sal_uInt32 nPoints, const SalPoint* pPtAry)
+{
+    basegfx::B2DPolygon aPolygon;
+    aPolygon.append(basegfx::B2DPoint(pPtAry->mnX, pPtAry->mnY), nPoints);
+    for (sal_uInt32 i = 1; i < nPoints; ++i)
+        aPolygon.setB2DPoint(i, basegfx::B2DPoint(pPtAry[i].mnX, pPtAry[i].mnY));
+    aPolygon.setClosed(false);
+
+    drawPolyLine(basegfx::B2DHomMatrix(), aPolygon, 0.0, 1.0, nullptr, basegfx::B2DLineJoin::Miter,
+                 css::drawing::LineCap_BUTT, basegfx::deg2rad(15.0) /*default*/, false);
+}
+
+void SkiaSalGraphicsImpl::drawPolygon(sal_uInt32 nPoints, const SalPoint* pPtAry)
+{
+    basegfx::B2DPolygon aPolygon;
+    aPolygon.append(basegfx::B2DPoint(pPtAry->mnX, pPtAry->mnY), nPoints);
+    for (sal_uInt32 i = 1; i < nPoints; ++i)
+        aPolygon.setB2DPoint(i, basegfx::B2DPoint(pPtAry[i].mnX, pPtAry[i].mnY));
+
+    drawPolyPolygon(basegfx::B2DHomMatrix(), basegfx::B2DPolyPolygon(aPolygon), 0.0);
+}
+
+void SkiaSalGraphicsImpl::drawPolyPolygon(sal_uInt32 nPoly, const sal_uInt32* pPoints,
+                                          PCONSTSALPOINT* pPtAry)
+{
+    basegfx::B2DPolyPolygon aPolyPolygon;
+    for (sal_uInt32 nPolygon = 0; nPolygon < nPoly; ++nPolygon)
+    {
+        sal_uInt32 nPoints = pPoints[nPolygon];
+        if (nPoints)
+        {
+            PCONSTSALPOINT pSalPoints = pPtAry[nPolygon];
+            basegfx::B2DPolygon aPolygon;
+            aPolygon.append(basegfx::B2DPoint(pSalPoints->mnX, pSalPoints->mnY), nPoints);
+            for (sal_uInt32 i = 1; i < nPoints; ++i)
+                aPolygon.setB2DPoint(i, basegfx::B2DPoint(pSalPoints[i].mnX, pSalPoints[i].mnY));
+
+            aPolyPolygon.append(aPolygon);
+        }
+    }
+
+    drawPolyPolygon(basegfx::B2DHomMatrix(), aPolyPolygon, 0.0);
+}
+
+bool SkiaSalGraphicsImpl::drawPolyPolygon(const basegfx::B2DHomMatrix& rObjectToDevice,
+                                          const basegfx::B2DPolyPolygon& rPolyPolygon,
+                                          double fTransparency)
+{
+    const bool bHasFill(mFillColor != SALCOLOR_NONE);
+    const bool bHasLine(mLineColor != SALCOLOR_NONE);
+
+    if (rPolyPolygon.count() == 0 || !(bHasFill || bHasLine) || fTransparency < 0.0
+        || fTransparency >= 1.0)
+        return true;
+
+    basegfx::B2DPolyPolygon aPolyPolygon(rPolyPolygon);
+    aPolyPolygon.transform(rObjectToDevice);
+
+    SAL_INFO("vcl.skia.trace", "drawpolypolygon(" << this << "): " << aPolyPolygon << ":"
+                                                  << mLineColor << ":" << mFillColor);
+
+    if (delayDrawPolyPolygon(aPolyPolygon, fTransparency))
+    {
+        scheduleFlush();
+        return true;
+    }
+
+    performDrawPolyPolygon(aPolyPolygon, fTransparency, mParent.getAntiAliasB2DDraw());
+    return true;
+}
+
+void SkiaSalGraphicsImpl::performDrawPolyPolygon(const basegfx::B2DPolyPolygon& aPolyPolygon,
+                                                 double fTransparency, bool useAA)
+{
+    preDraw();
+
+    SkPath polygonPath;
+    bool hasOnlyOrthogonal = true;
+    addPolyPolygonToPath(aPolyPolygon, polygonPath, &hasOnlyOrthogonal);
+    polygonPath.setFillType(SkPathFillType::kEvenOdd);
+    addXorRegion(polygonPath.getBounds());
+
+    SkPaint aPaint;
+    aPaint.setAntiAlias(useAA);
+
+    // For lines we use toSkX()/toSkY() in order to pass centers of pixels to Skia,
+    // as that leads to better results with floating-point coordinates
+    // (e.g. https://bugs.chromium.org/p/skia/issues/detail?id=9611).
+    // But that means that we generally need to use it also for areas, so that they
+    // line up properly if used together (tdf#134346).
+    // On the other hand, with AA enabled and rectangular areas, this leads to fuzzy
+    // edges (tdf#137329). But since rectangular areas line up perfectly to pixels
+    // everywhere, it shouldn't be necessary to do this for them.
+    // So if AA is enabled, avoid this fixup for rectangular areas.
+    if (!useAA || !hasOnlyOrthogonal)
+    {
+        // We normally use pixel at their center positions, but slightly off (see toSkX/Y()).
+        // With AA lines that "slightly off" causes tiny changes of color, making some tests
+        // fail. Since moving AA-ed line slightly to a side doesn't cause any real visual
+        // difference, just place exactly at the center. tdf#134346
+        const SkScalar posFix = useAA ? toSkXYFix : 0;
+        polygonPath.offset(toSkX(0) + posFix, toSkY(0) + posFix, nullptr);
+    }
+    if (mFillColor != SALCOLOR_NONE)
+    {
+        aPaint.setColor(toSkColorWithTransparency(mFillColor, fTransparency));
+        aPaint.setStyle(SkPaint::kFill_Style);
+        // HACK: If the polygon is just a line, it still should be drawn. But when filling
+        // Skia doesn't draw empty polygons, so in that case ensure the line is drawn.
+        if (mLineColor == SALCOLOR_NONE && polygonPath.getBounds().isEmpty())
+            aPaint.setStyle(SkPaint::kStroke_Style);
+        getDrawCanvas()->drawPath(polygonPath, aPaint);
+    }
+    if (mLineColor != SALCOLOR_NONE)
+    {
+        aPaint.setColor(toSkColorWithTransparency(mLineColor, fTransparency));
+        aPaint.setStyle(SkPaint::kStroke_Style);
+        getDrawCanvas()->drawPath(polygonPath, aPaint);
+    }
+    postDraw();
+#if defined LINUX
+    // WORKAROUND: The logo in the about dialog has drawing errors. This seems to happen
+    // only on Linux (not Windows on the same machine), with both AMDGPU and Mesa,
+    // and only when antialiasing is enabled. Flushing seems to avoid the problem.
+    if (useAA && SkiaHelper::getVendor() == DriverBlocklist::VendorAMD)
+        mSurface->flushAndSubmit();
+#endif
+}
+
+namespace
+{
+struct LessThan
+{
+    bool operator()(const basegfx::B2DPoint& point1, const basegfx::B2DPoint& point2) const
+    {
+        if (basegfx::fTools::equal(point1.getX(), point2.getX()))
+            return basegfx::fTools::less(point1.getY(), point2.getY());
+        return basegfx::fTools::less(point1.getX(), point2.getX());
+    }
+};
+} // namespace
+
+bool SkiaSalGraphicsImpl::delayDrawPolyPolygon(const basegfx::B2DPolyPolygon& aPolyPolygon,
+                                               double fTransparency)
+{
+    // There is some code that needlessly subdivides areas into adjacent rectangles,
+    // but Skia doesn't line them up perfectly if AA is enabled (e.g. Cairo, Qt5 do,
+    // but Skia devs claim it's working as intended
+    // https://groups.google.com/d/msg/skia-discuss/NlKpD2X_5uc/Vuwd-kyYBwAJ).
+    // An example is tdf#133016, which triggers SvgStyleAttributes::add_stroke()
+    // implementing a line stroke as a bunch of polygons instead of just one, and
+    // SvgLinearAtomPrimitive2D::create2DDecomposition() creates a gradient
+    // as a series of polygons of gradually changing color. Those places should be
+    // changed, but try to merge those split polygons back into the original one,
+    // where the needlessly created edges causing problems will not exist.
+    // This means drawing of such polygons needs to be delayed, so that they can
+    // be possibly merged with the next one.
+    // Merge only polygons of the same properties (color, etc.), so the gradient problem
+    // actually isn't handled here.
+
+    // Only AA polygons need merging, because they do not line up well because of the AA of the edges.
+    if (!mParent.getAntiAliasB2DDraw())
+        return false;
+    // Only filled polygons without an outline are problematic.
+    if (mFillColor == SALCOLOR_NONE || mLineColor != SALCOLOR_NONE)
+        return false;
+    // Merge only simple polygons, real polypolygons most likely aren't needlessly split,
+    // so they do not need joining.
+    if (aPolyPolygon.count() != 1)
+        return false;
+    // If the polygon is not closed, it doesn't mark an area to be filled.
+    if (!aPolyPolygon.isClosed())
+        return false;
+    // If a polygon does not contain a straight line, i.e. it's all curves, then do not merge.
+    // First of all that's even more expensive, and second it's very unlikely that it's a polygon
+    // split into more polygons.
+    if (!polygonContainsLine(aPolyPolygon))
+        return false;
+
+    if (mLastPolyPolygonInfo.polygons.size() != 0
+        && (mLastPolyPolygonInfo.transparency != fTransparency
+            || !mLastPolyPolygonInfo.bounds.overlaps(aPolyPolygon.getB2DRange())))
+    {
+        checkPendingDrawing(); // Cannot be parts of the same larger polygon, draw the last and reset.
+    }
+    if (!mLastPolyPolygonInfo.polygons.empty())
+    {
+        assert(aPolyPolygon.count() == 1);
+        assert(mLastPolyPolygonInfo.polygons.back().count() == 1);
+        // Check if the new and the previous polygon share at least one point. If not, then they
+        // cannot be adjacent polygons, so there's no point in trying to merge them.
+        bool sharePoint = false;
+        const basegfx::B2DPolygon& poly1 = aPolyPolygon.getB2DPolygon(0);
+        const basegfx::B2DPolygon& poly2 = mLastPolyPolygonInfo.polygons.back().getB2DPolygon(0);
+        o3tl::sorted_vector<basegfx::B2DPoint, LessThan> poly1Points; // for O(n log n)
+        poly1Points.reserve(poly1.count());
+        for (sal_uInt32 i = 0; i < poly1.count(); ++i)
+            poly1Points.insert(poly1.getB2DPoint(i));
+        for (sal_uInt32 i = 0; i < poly2.count(); ++i)
+            if (poly1Points.find(poly2.getB2DPoint(i)) != poly1Points.end())
+            {
+                sharePoint = true;
+                break;
+            }
+        if (!sharePoint)
+            checkPendingDrawing(); // Draw the previous one and reset.
+    }
+    // Collect the polygons that can be possibly merged. Do the merging only once at the end,
+    // because it's not a cheap operation.
+    mLastPolyPolygonInfo.polygons.push_back(aPolyPolygon);
+    mLastPolyPolygonInfo.bounds.expand(aPolyPolygon.getB2DRange());
+    mLastPolyPolygonInfo.transparency = fTransparency;
+    return true;
+}
+
+void SkiaSalGraphicsImpl::checkPendingDrawing()
+{
+    if (mLastPolyPolygonInfo.polygons.size() != 0)
+    { // Flush any pending polygon drawing.
+        basegfx::B2DPolyPolygonVector polygons;
+        std::swap(polygons, mLastPolyPolygonInfo.polygons);
+        double transparency = mLastPolyPolygonInfo.transparency;
+        mLastPolyPolygonInfo.bounds.reset();
+        if (polygons.size() == 1)
+            performDrawPolyPolygon(polygons.front(), transparency, true);
+        else
+            // TODO: tdf#136222 shows that basegfx::utils::mergeToSinglePolyPolygon() is unreliable
+            // in corner cases, possibly either a bug or rounding errors somewhere.
+            performDrawPolyPolygon(basegfx::utils::mergeToSinglePolyPolygon(polygons), transparency,
+                                   true);
+    }
+}
+
+bool SkiaSalGraphicsImpl::drawPolyLine(const basegfx::B2DHomMatrix& rObjectToDevice,
+                                       const basegfx::B2DPolygon& rPolyLine, double fTransparency,
+                                       double fLineWidth, const std::vector<double>* pStroke,
+                                       basegfx::B2DLineJoin eLineJoin,
+                                       css::drawing::LineCap eLineCap, double fMiterMinimumAngle,
+                                       bool bPixelSnapHairline)
+{
+    if (!rPolyLine.count() || fTransparency < 0.0 || fTransparency > 1.0
+        || mLineColor == SALCOLOR_NONE)
+    {
+        return true;
+    }
+
+    preDraw();
+    SAL_INFO("vcl.skia.trace", "drawpolyline(" << this << "): " << rPolyLine << ":" << mLineColor);
+
+    // tdf#124848 get correct LineWidth in discrete coordinates,
+    if (fLineWidth == 0) // hairline
+        fLineWidth = 1.0;
+    else // Adjust line width for object-to-device scale.
+        fLineWidth = (rObjectToDevice * basegfx::B2DVector(fLineWidth, 0)).getLength();
+
+    // Transform to DeviceCoordinates, get DeviceLineWidth, execute PixelSnapHairline
+    basegfx::B2DPolyPolygon aPolyPolygonLine;
+    aPolyPolygonLine.append(rPolyLine);
+    aPolyPolygonLine.transform(rObjectToDevice);
+    if (bPixelSnapHairline)
+    {
+        aPolyPolygonLine = basegfx::utils::snapPointsOfHorizontalOrVerticalEdges(aPolyPolygonLine);
+    }
+
+    // Setup Line Join
+    SkPaint::Join eSkLineJoin = SkPaint::kMiter_Join;
+    switch (eLineJoin)
+    {
+        case basegfx::B2DLineJoin::Bevel:
+            eSkLineJoin = SkPaint::kBevel_Join;
+            break;
+        case basegfx::B2DLineJoin::Round:
+            eSkLineJoin = SkPaint::kRound_Join;
+            break;
+        case basegfx::B2DLineJoin::NONE:
+        case basegfx::B2DLineJoin::Miter:
+            eSkLineJoin = SkPaint::kMiter_Join;
+            break;
+    }
+
+    // convert miter minimum angle to miter limit
+    double fMiterLimit = 1.0 / std::sin(fMiterMinimumAngle / 2.0);
+
+    // Setup Line Cap
+    SkPaint::Cap eSkLineCap(SkPaint::kButt_Cap);
+
+    switch (eLineCap)
+    {
+        case css::drawing::LineCap_ROUND:
+            eSkLineCap = SkPaint::kRound_Cap;
+            break;
+        case css::drawing::LineCap_SQUARE:
+            eSkLineCap = SkPaint::kSquare_Cap;
+            break;
+        default: // css::drawing::LineCap_BUTT:
+            eSkLineCap = SkPaint::kButt_Cap;
+            break;
+    }
+
+    SkPaint aPaint;
+    aPaint.setStyle(SkPaint::kStroke_Style);
+    aPaint.setStrokeCap(eSkLineCap);
+    aPaint.setStrokeJoin(eSkLineJoin);
+    aPaint.setColor(toSkColorWithTransparency(mLineColor, fTransparency));
+    aPaint.setStrokeMiter(fMiterLimit);
+    aPaint.setStrokeWidth(fLineWidth);
+    aPaint.setAntiAlias(mParent.getAntiAliasB2DDraw());
+    // See the tdf#134346 comment above.
+    const SkScalar posFix = mParent.getAntiAliasB2DDraw() ? toSkXYFix : 0;
+
+    if (pStroke && std::accumulate(pStroke->begin(), pStroke->end(), 0.0) != 0)
+    {
+        std::vector<SkScalar> intervals;
+        // Transform size by the matrix.
+        for (double stroke : *pStroke)
+            intervals.push_back((rObjectToDevice * basegfx::B2DVector(stroke, 0)).getLength());
+        aPaint.setPathEffect(SkDashPathEffect::Make(intervals.data(), intervals.size(), 0));
+    }
+
+    // Skia does not support basegfx::B2DLineJoin::NONE, so in that case batch only if lines
+    // are not wider than a pixel.
+    if (eLineJoin != basegfx::B2DLineJoin::NONE || fLineWidth <= 1.0)
+    {
+        SkPath aPath;
+        aPath.setFillType(SkPathFillType::kEvenOdd);
+        for (sal_uInt32 a(0); a < aPolyPolygonLine.count(); a++)
+            addPolygonToPath(aPolyPolygonLine.getB2DPolygon(a), aPath);
+        aPath.offset(toSkX(0) + posFix, toSkY(0) + posFix, nullptr);
+        addXorRegion(aPath.getBounds());
+        getDrawCanvas()->drawPath(aPath, aPaint);
+    }
+    else
+    {
+        for (sal_uInt32 i = 0; i < aPolyPolygonLine.count(); ++i)
+        {
+            const basegfx::B2DPolygon& rPolygon = aPolyPolygonLine.getB2DPolygon(i);
+            sal_uInt32 nPoints = rPolygon.count();
+            bool bClosed = rPolygon.isClosed();
+            for (sal_uInt32 j = 0; j < (bClosed ? nPoints : nPoints - 1); ++j)
+            {
+                sal_uInt32 index1 = (j + 0) % nPoints;
+                sal_uInt32 index2 = (j + 1) % nPoints;
+                SkPath aPath;
+                aPath.moveTo(rPolygon.getB2DPoint(index1).getX(),
+                             rPolygon.getB2DPoint(index1).getY());
+                aPath.lineTo(rPolygon.getB2DPoint(index2).getX(),
+                             rPolygon.getB2DPoint(index2).getY());
+
+                aPath.offset(toSkX(0) + posFix, toSkY(0) + posFix, nullptr);
+                addXorRegion(aPath.getBounds());
+                getDrawCanvas()->drawPath(aPath, aPaint);
+            }
+        }
+    }
+
+    postDraw();
+
+    return true;
+}
+
+bool SkiaSalGraphicsImpl::drawPolyLineBezier(sal_uInt32, const SalPoint*, const PolyFlags*)
+{
+    // TODO?
+    return false;
+}
+
+bool SkiaSalGraphicsImpl::drawPolygonBezier(sal_uInt32, const SalPoint*, const PolyFlags*)
+{
+    // TODO?
+    return false;
+}
+
+bool SkiaSalGraphicsImpl::drawPolyPolygonBezier(sal_uInt32, const sal_uInt32*,
+                                                const SalPoint* const*, const PolyFlags* const*)
+{
+    // TODO?
+    return false;
+}
+
+static void copyArea(SkCanvas* canvas, sk_sp<SkSurface> surface, long nDestX, long nDestY,
+                     long nSrcX, long nSrcY, long nSrcWidth, long nSrcHeight, bool srcIsRaster,
+                     bool destIsRaster)
+{
+    // Using SkSurface::draw() should be more efficient than SkSurface::makeImageSnapshot(),
+    // because it may detect copying to itself and avoid some needless copies.
+    // But it has problems with drawing to itself
+    // (https://groups.google.com/forum/#!topic/skia-discuss/6yiuw24jv0I) and also
+    // raster surfaces do not avoid a copy of the source
+    // (https://groups.google.com/forum/#!topic/skia-discuss/S3FMpCi82k0).
+    // Finally, there's not much point if one of them is raster and the other is not (chrome/m86 even crashes).
+    if (canvas == surface->getCanvas() || srcIsRaster || (srcIsRaster != destIsRaster))
+    {
+        SkPaint paint;
+        paint.setBlendMode(SkBlendMode::kSrc); // copy as is, including alpha
+        canvas->drawImageRect(SkiaHelper::makeCheckedImageSnapshot(surface),
+                              SkIRect::MakeXYWH(nSrcX, nSrcY, nSrcWidth, nSrcHeight),
+                              SkRect::MakeXYWH(nDestX, nDestY, nSrcWidth, nSrcHeight), &paint);
+        return;
+    }
+    // SkCanvas::draw() cannot do a subrectangle, so clip.
+    canvas->save();
+    canvas->clipRect(SkRect::MakeXYWH(nDestX, nDestY, nSrcWidth, nSrcHeight));
+    SkPaint paint;
+    paint.setBlendMode(SkBlendMode::kSrc); // copy as is, including alpha
+    surface->draw(canvas, nDestX - nSrcX, nDestY - nSrcY, &paint);
+    canvas->restore();
+}
+
+void SkiaSalGraphicsImpl::copyArea(long nDestX, long nDestY, long nSrcX, long nSrcY, long nSrcWidth,
+                                   long nSrcHeight, bool /*bWindowInvalidate*/)
+{
+    if (nDestX == nSrcX && nDestY == nSrcY)
+        return;
+    preDraw();
+    SAL_INFO("vcl.skia.trace", "copyarea("
+                                   << this << "): " << Point(nSrcX, nSrcY) << "->"
+                                   << SkIRect::MakeXYWH(nDestX, nDestY, nSrcWidth, nSrcHeight));
+    assert(!mXorMode);
+    ::copyArea(getDrawCanvas(), mSurface, nDestX, nDestY, nSrcX, nSrcY, nSrcWidth, nSrcHeight,
+               !isGPU(), !isGPU());
+    postDraw();
+}
+
+void SkiaSalGraphicsImpl::copyBits(const SalTwoRect& rPosAry, SalGraphics* pSrcGraphics)
+{
+    preDraw();
+    SkiaSalGraphicsImpl* src;
+    if (pSrcGraphics)
+    {
+        assert(dynamic_cast<SkiaSalGraphicsImpl*>(pSrcGraphics->GetImpl()));
+        src = static_cast<SkiaSalGraphicsImpl*>(pSrcGraphics->GetImpl());
+        src->checkSurface();
+        src->flushDrawing();
+    }
+    else
+    {
+        src = this;
+        assert(!mXorMode);
+    }
+    if (rPosAry.mnSrcWidth == rPosAry.mnDestWidth && rPosAry.mnSrcHeight == rPosAry.mnDestHeight)
+    {
+        auto srcDebug = [&]() -> std::string {
+            if (src == this)
+                return "(self)";
+            else
+            {
+                std::ostringstream stream;
+                stream << "(" << src << ")";
+                return stream.str();
+            }
+        };
+        SAL_INFO("vcl.skia.trace",
+                 "copybits(" << this << "): " << srcDebug() << " copy area: " << rPosAry);
+        ::copyArea(getDrawCanvas(), src->mSurface, rPosAry.mnDestX, rPosAry.mnDestY, rPosAry.mnSrcX,
+                   rPosAry.mnSrcY, rPosAry.mnDestWidth, rPosAry.mnDestHeight, !src->isGPU(),
+                   !isGPU());
+    }
+    else
+    {
+        SAL_INFO("vcl.skia.trace", "copybits(" << this << "): (" << src << "): " << rPosAry);
+        // Do not use makeImageSnapshot(rect), as that one may make a needless data copy.
+        sk_sp<SkImage> image = SkiaHelper::makeCheckedImageSnapshot(src->mSurface);
+        SkPaint paint;
+        paint.setBlendMode(SkBlendMode::kSrc); // copy as is, including alpha
+        if (rPosAry.mnSrcWidth != rPosAry.mnDestWidth
+            || rPosAry.mnSrcHeight != rPosAry.mnDestHeight)
+            paint.setFilterQuality(kHigh_SkFilterQuality);
+        getDrawCanvas()->drawImageRect(image,
+                                       SkIRect::MakeXYWH(rPosAry.mnSrcX, rPosAry.mnSrcY,
+                                                         rPosAry.mnSrcWidth, rPosAry.mnSrcHeight),
+                                       SkRect::MakeXYWH(rPosAry.mnDestX, rPosAry.mnDestY,
+                                                        rPosAry.mnDestWidth, rPosAry.mnDestHeight),
+                                       &paint);
+    }
+    assert(!mXorMode);
+    postDraw();
+}
+
+bool SkiaSalGraphicsImpl::blendBitmap(const SalTwoRect& rPosAry, const SalBitmap& rBitmap)
+{
+    if (checkInvalidSourceOrDestination(rPosAry))
+        return false;
+
+    assert(dynamic_cast<const SkiaSalBitmap*>(&rBitmap));
+    const SkiaSalBitmap& rSkiaBitmap = static_cast<const SkiaSalBitmap&>(rBitmap);
+    // This is used by VirtualDevice in the alpha mode for the "alpha" layer which
+    // is actually one-minus-alpha (opacity). Therefore white=0xff=transparent,
+    // black=0x00=opaque. So the result is transparent only if both the inputs
+    // are transparent. Since for blending operations white=1.0 and black=0.0,
+    // kMultiply should handle exactly that (transparent*transparent=transparent,
+    // opaque*transparent=opaque). And guessing from the "floor" in TYPE_BLEND in opengl's
+    // combinedTextureFragmentShader.glsl, the layer is not even alpha values but
+    // simply yes-or-no mask.
+    // See also blendAlphaBitmap().
+    drawImage(rPosAry, rSkiaBitmap.GetSkImage(), SkBlendMode::kMultiply);
+    return true;
+}
+
+bool SkiaSalGraphicsImpl::blendAlphaBitmap(const SalTwoRect& rPosAry,
+                                           const SalBitmap& rSourceBitmap,
+                                           const SalBitmap& rMaskBitmap,
+                                           const SalBitmap& rAlphaBitmap)
+{
+    if (checkInvalidSourceOrDestination(rPosAry))
+        return false;
+
+    assert(dynamic_cast<const SkiaSalBitmap*>(&rSourceBitmap));
+    assert(dynamic_cast<const SkiaSalBitmap*>(&rMaskBitmap));
+    assert(dynamic_cast<const SkiaSalBitmap*>(&rAlphaBitmap));
+    const SkiaSalBitmap& rSkiaSourceBitmap = static_cast<const SkiaSalBitmap&>(rSourceBitmap);
+    const SkiaSalBitmap& rSkiaMaskBitmap = static_cast<const SkiaSalBitmap&>(rMaskBitmap);
+    const SkiaSalBitmap& rSkiaAlphaBitmap = static_cast<const SkiaSalBitmap&>(rAlphaBitmap);
+
+    // This was originally implemented for the OpenGL drawing method and it is poorly documented.
+    // The source and mask bitmaps are the usual data and alpha bitmaps, and 'alpha'
+    // is the "alpha" layer of the VirtualDevice (the alpha in VirtualDevice is also stored
+    // as a separate bitmap). Now if I understand it correctly these two alpha masks first need
+    // to be combined into the actual alpha mask to be used. The formula for TYPE_BLEND
+    // in opengl's combinedTextureFragmentShader.glsl is
+    // "result_alpha = 1.0 - (1.0 - floor(alpha)) * mask".
+    // See also blendBitmap().
+
+    // First do the "( 1 - alpha ) * mask"
+    // (no idea how to do "floor", but hopefully not needed in practice).
+    sk_sp<SkShader> shaderAlpha
+        = SkShaders::Blend(SkBlendMode::kDstOut, rSkiaMaskBitmap.GetAlphaSkImage()->makeShader(),
+                           rSkiaAlphaBitmap.GetAlphaSkImage()->makeShader());
+    // And now draw the bitmap with "1 - x", where x is the "( 1 - alpha ) * mask".
+    sk_sp<SkShader> shader = SkShaders::Blend(SkBlendMode::kSrcOut, shaderAlpha,
+                                              rSkiaSourceBitmap.GetSkImage()->makeShader());
+    drawShader(rPosAry, shader);
+    return true;
+}
+
+void SkiaSalGraphicsImpl::drawBitmap(const SalTwoRect& rPosAry, const SalBitmap& rSalBitmap)
+{
+    if (checkInvalidSourceOrDestination(rPosAry))
+        return;
+
+    assert(dynamic_cast<const SkiaSalBitmap*>(&rSalBitmap));
+    const SkiaSalBitmap& rSkiaSourceBitmap = static_cast<const SkiaSalBitmap&>(rSalBitmap);
+
+    drawImage(rPosAry, rSkiaSourceBitmap.GetSkImage());
+}
+
+void SkiaSalGraphicsImpl::drawBitmap(const SalTwoRect& rPosAry, const SalBitmap& rSalBitmap,
+                                     const SalBitmap& rMaskBitmap)
+{
+    drawAlphaBitmap(rPosAry, rSalBitmap, rMaskBitmap);
+}
+
+void SkiaSalGraphicsImpl::drawMask(const SalTwoRect& rPosAry, const SalBitmap& rSalBitmap,
+                                   Color nMaskColor)
+{
+    assert(dynamic_cast<const SkiaSalBitmap*>(&rSalBitmap));
+    const SkiaSalBitmap& skiaBitmap = static_cast<const SkiaSalBitmap&>(rSalBitmap);
+    drawShader(rPosAry,
+               SkShaders::Blend(SkBlendMode::kDstOut, // VCL alpha is one-minus-alpha.
+                                SkShaders::Color(toSkColor(nMaskColor)),
+                                skiaBitmap.GetAlphaSkImage()->makeShader()));
+}
+
+std::shared_ptr<SalBitmap> SkiaSalGraphicsImpl::getBitmap(long nX, long nY, long nWidth,
+                                                          long nHeight)
+{
+    SkiaZone zone;
+    checkSurface();
+    SAL_INFO("vcl.skia.trace",
+             "getbitmap(" << this << "): " << SkIRect::MakeXYWH(nX, nY, nWidth, nHeight));
+    flushDrawing();
+    // TODO makeImageSnapshot(rect) may copy the data, which may be a waste if this is used
+    // e.g. for VirtualDevice's lame alpha blending, in which case the image will eventually end up
+    // in blendAlphaBitmap(), where we could simply use the proper rect of the image.
+    sk_sp<SkImage> image = SkiaHelper::makeCheckedImageSnapshot(
+        mSurface, SkIRect::MakeXYWH(nX, nY, nWidth, nHeight));
+    return std::make_shared<SkiaSalBitmap>(image);
+}
+
+Color SkiaSalGraphicsImpl::getPixel(long nX, long nY)
+{
+    SkiaZone zone;
+    checkSurface();
+    SAL_INFO("vcl.skia.trace", "getpixel(" << this << "): " << Point(nX, nY));
+    flushDrawing();
+    // This is presumably slow, but getPixel() should be generally used only by unit tests.
+    SkBitmap bitmap;
+    if (!bitmap.tryAllocN32Pixels(GetWidth(), GetHeight()))
+        abort();
+    if (!mSurface->readPixels(bitmap, 0, 0))
+        abort();
+    return fromSkColor(bitmap.getColor(nX, nY));
+}
+
+void SkiaSalGraphicsImpl::invert(basegfx::B2DPolygon const& rPoly, SalInvert eFlags)
+{
+    preDraw();
+    SAL_INFO("vcl.skia.trace", "invert(" << this << "): " << rPoly << ":" << int(eFlags));
+    assert(!mXorMode);
+    // Intel Vulkan drivers (up to current 0.401.3889) have a problem
+    // with SkBlendMode::kDifference(?) and surfaces wider than 1024 pixels, resulting
+    // in drawing errors. Work that around by fetching the relevant part of the surface
+    // and drawing using CPU.
+    bool intelHack
+        = (isGPU() && SkiaHelper::getVendor() == DriverBlocklist::VendorIntel && !mXorMode);
+    // TrackFrame just inverts a dashed path around the polygon
+    if (eFlags == SalInvert::TrackFrame)
+    {
+        SkPath aPath;
+        addPolygonToPath(rPoly, aPath);
+        aPath.setFillType(SkPathFillType::kEvenOdd);
+        // TrackFrame is not supposed to paint outside of the polygon (usually rectangle),
+        // but wider stroke width usually results in that, so ensure the requirement
+        // by clipping.
+        SkAutoCanvasRestore autoRestore(getDrawCanvas(), true);
+        getDrawCanvas()->clipRect(aPath.getBounds(), SkClipOp::kIntersect, false);
+        SkPaint aPaint;
+        aPaint.setStrokeWidth(2);
+        float intervals[] = { 4.0f, 4.0f };
+        aPaint.setStyle(SkPaint::kStroke_Style);
+        aPaint.setPathEffect(SkDashPathEffect::Make(intervals, SK_ARRAY_COUNT(intervals), 0));
+        aPaint.setColor(SkColorSetARGB(255, 255, 255, 255));
+        aPaint.setBlendMode(SkBlendMode::kDifference);
+        if (!intelHack)
+            getDrawCanvas()->drawPath(aPath, aPaint);
+        else
+        {
+            SkRect area;
+            aPath.getBounds().roundOut(&area);
+            SkRect size = SkRect::MakeWH(area.width(), area.height());
+            sk_sp<SkSurface> surface = SkSurface::MakeRasterN32Premul(area.width(), area.height());
+            SkPaint copy;
+            copy.setBlendMode(SkBlendMode::kSrc);
+            flushDrawing();
+            surface->getCanvas()->drawImageRect(SkiaHelper::makeCheckedImageSnapshot(mSurface),
+                                                area, size, &copy);
+            aPath.offset(-area.x(), -area.y());
+            surface->getCanvas()->drawPath(aPath, aPaint);
+            getDrawCanvas()->drawImageRect(SkiaHelper::makeCheckedImageSnapshot(surface), size,
+                                           area, &copy);
+        }
+    }
+    else
+    {
+        SkPath aPath;
+        addPolygonToPath(rPoly, aPath);
+        aPath.setFillType(SkPathFillType::kEvenOdd);
+        SkPaint aPaint;
+        aPaint.setColor(SkColorSetARGB(255, 255, 255, 255));
+        aPaint.setStyle(SkPaint::kFill_Style);
+        aPaint.setBlendMode(SkBlendMode::kDifference);
+
+        // N50 inverts in checker pattern
+        if (eFlags == SalInvert::N50)
+        {
+            // This creates 2x2 checker pattern bitmap
+            // TODO Use SkiaHelper::createSkSurface() and cache the image
+            SkBitmap aBitmap;
+            aBitmap.allocN32Pixels(2, 2);
+            const SkPMColor white = SkPreMultiplyARGB(0xFF, 0xFF, 0xFF, 0xFF);
+            const SkPMColor black = SkPreMultiplyARGB(0xFF, 0x00, 0x00, 0x00);
+            SkPMColor* scanline;
+            scanline = aBitmap.getAddr32(0, 0);
+            *scanline++ = white;
+            *scanline++ = black;
+            scanline = aBitmap.getAddr32(0, 1);
+            *scanline++ = black;
+            *scanline++ = white;
+            aBitmap.setImmutable();
+            // The bitmap is repeated in both directions the checker pattern is as big
+            // as the polygon (usually rectangle)
+            aPaint.setShader(aBitmap.makeShader(SkTileMode::kRepeat, SkTileMode::kRepeat));
+        }
+        if (!intelHack)
+            getDrawCanvas()->drawPath(aPath, aPaint);
+        else
+        {
+            SkRect area;
+            aPath.getBounds().roundOut(&area);
+            SkRect size = SkRect::MakeWH(area.width(), area.height());
+            sk_sp<SkSurface> surface = SkSurface::MakeRasterN32Premul(area.width(), area.height());
+            SkPaint copy;
+            copy.setBlendMode(SkBlendMode::kSrc);
+            flushDrawing();
+            surface->getCanvas()->drawImageRect(SkiaHelper::makeCheckedImageSnapshot(mSurface),
+                                                area, size, &copy);
+            aPath.offset(-area.x(), -area.y());
+            surface->getCanvas()->drawPath(aPath, aPaint);
+            getDrawCanvas()->drawImageRect(SkiaHelper::makeCheckedImageSnapshot(surface), size,
+                                           area, &copy);
+        }
+    }
+    postDraw();
+}
+
+void SkiaSalGraphicsImpl::invert(long nX, long nY, long nWidth, long nHeight, SalInvert eFlags)
+{
+    basegfx::B2DRectangle aRectangle(nX, nY, nX + nWidth, nY + nHeight);
+    auto aRect = basegfx::utils::createPolygonFromRect(aRectangle);
+    invert(aRect, eFlags);
+}
+
+void SkiaSalGraphicsImpl::invert(sal_uInt32 nPoints, const SalPoint* pPointArray, SalInvert eFlags)
+{
+    basegfx::B2DPolygon aPolygon;
+    aPolygon.append(basegfx::B2DPoint(pPointArray[0].mnX, pPointArray[0].mnY), nPoints);
+    for (sal_uInt32 i = 1; i < nPoints; ++i)
+    {
+        aPolygon.setB2DPoint(i, basegfx::B2DPoint(pPointArray[i].mnX, pPointArray[i].mnY));
+    }
+    aPolygon.setClosed(true);
+
+    invert(aPolygon, eFlags);
+}
+
+bool SkiaSalGraphicsImpl::drawEPS(long, long, long, long, void*, sal_uInt32)
+{
+    // TODO?
+    return false;
+}
+
+// Create SkImage from a bitmap and possibly an alpha mask (the usual VCL one-minus-alpha),
+// with the given target size. Result will be possibly cached, unless disabled.
+sk_sp<SkImage> SkiaSalGraphicsImpl::mergeCacheBitmaps(const SkiaSalBitmap& bitmap,
+                                                      const SkiaSalBitmap* alphaBitmap,
+                                                      const Size targetSize)
+{
+    sk_sp<SkImage> image;
+    // GPU-accelerated drawing with SkShader should be fast enough to not need caching.
+    if (isGPU())
+        return image;
+    if (targetSize.IsEmpty())
+        return image;
+    // Probably not much point in caching of just doing a copy.
+    if (alphaBitmap == nullptr && targetSize == bitmap.GetSize())
+        return image;
+    // Image too small to be worth caching.
+    if (bitmap.GetSize().Width() < 100 && bitmap.GetSize().Height() < 100
+        && targetSize.Width() < 100 && targetSize.Height() < 100)
+        return image;
+    // In some cases (tdf#134237) the draw size may be very large. In that case it's
+    // better to rely on Skia to clip and draw only the necessary, rather than prepare
+    // a very large image only to not use most of it.
+    if (targetSize.Width() > GetWidth() || targetSize.Height() > GetHeight())
+    {
+        // This is a bit tricky. The condition above just checks that at least a part of the resulting
+        // image will not be used (it's larger then our drawing area). But this may often happen
+        // when just scrolling a document with a large image, where the caching may very well be worth it.
+        // Since the problem is mainly the cost of upscaling and then the size of the resulting bitmap,
+        // compute a ratio of how much this is going to be scaled up, how much this is larger than
+        // the drawing area, and then refuse to cache if it's too much.
+        const double upscaleRatio = 1.0 * targetSize.Width() / bitmap.GetSize().Width()
+                                    * targetSize.Height() / bitmap.GetSize().Height();
+        const double oversizeRatio
+            = 1.0 * targetSize.Width() / GetWidth() * targetSize.Height() / GetHeight();
+        const double ratio = upscaleRatio * oversizeRatio;
+        if (ratio > 10)
+        {
+            SAL_INFO("vcl.skia.trace", "mergecachebitmaps("
+                                           << this << "): not caching upscaling, ratio:" << ratio
+                                           << ", " << bitmap.GetSize() << "->" << targetSize
+                                           << " in " << Size(GetWidth(), GetHeight()));
+            return image;
+        }
+    }
+    OString key;
+    OStringBuffer keyBuf;
+    keyBuf.append(targetSize.Width())
+        .append("x")
+        .append(targetSize.Height())
+        .append("_0x")
+        .append(reinterpret_cast<sal_IntPtr>(&bitmap), 16)
+        .append("_0x")
+        .append(reinterpret_cast<sal_IntPtr>(alphaBitmap), 16)
+        .append("_")
+        .append(static_cast<sal_Int64>(bitmap.GetSkImage()->uniqueID()));
+    if (alphaBitmap)
+        keyBuf.append("_").append(
+            static_cast<sal_Int64>(alphaBitmap->GetAlphaSkImage()->uniqueID()));
+    key = keyBuf.makeStringAndClear();
+    image = SkiaHelper::findCachedImage(key);
+    if (image)
+    {
+        assert(image->width() == targetSize.Width() && image->height() == targetSize.Height());
+        return image;
+    }
+    // Combine bitmap + alpha bitmap into one temporary bitmap with alpha.
+    // If scaling is needed, first apply the alpha, then scale, otherwise the scaling might affect the alpha values.
+    if (alphaBitmap && targetSize != bitmap.GetSize())
+    {
+        sk_sp<SkSurface> mergedSurface = SkiaHelper::createSkSurface(bitmap.GetSize());
+        if (!mergedSurface)
+            return nullptr;
+        SkPaint paint;
+        paint.setBlendMode(SkBlendMode::kSrc); // copy as is, including alpha
+        mergedSurface->getCanvas()->drawImage(bitmap.GetSkImage(), 0, 0, &paint);
+        paint.setBlendMode(SkBlendMode::kDstOut); // VCL alpha is one-minus-alpha
+        mergedSurface->getCanvas()->drawImage(alphaBitmap->GetAlphaSkImage(), 0, 0, &paint);
+        sk_sp<SkSurface> scaledSurface = SkiaHelper::createSkSurface(targetSize);
+        if (!scaledSurface)
+            return nullptr;
+        paint.setBlendMode(SkBlendMode::kSrc); // copy as is, including alpha
+        paint.setFilterQuality(kHigh_SkFilterQuality);
+        scaledSurface->getCanvas()->drawImageRect(
+            mergedSurface->makeImageSnapshot(),
+            SkRect::MakeXYWH(0, 0, bitmap.GetSize().Width(), bitmap.GetSize().Height()),
+            SkRect::MakeXYWH(0, 0, targetSize.Width(), targetSize.Height()), &paint);
+        image = scaledSurface->makeImageSnapshot();
+    }
+    else // No alpha or no scaling, scale directly.
+    {
+        sk_sp<SkSurface> tmpSurface = SkiaHelper::createSkSurface(targetSize);
+        if (!tmpSurface)
+            return nullptr;
+        SkCanvas* canvas = tmpSurface->getCanvas();
+        SkAutoCanvasRestore autoRestore(canvas, true);
+        SkPaint paint;
+        if (targetSize != bitmap.GetSize())
+        {
+            SkMatrix matrix;
+            matrix.set(SkMatrix::kMScaleX, 1.0 * targetSize.Width() / bitmap.GetSize().Width());
+            matrix.set(SkMatrix::kMScaleY, 1.0 * targetSize.Height() / bitmap.GetSize().Height());
+            canvas->concat(matrix);
+            paint.setFilterQuality(kHigh_SkFilterQuality);
+        }
+        paint.setBlendMode(SkBlendMode::kSrc); // copy as is, including alpha
+        canvas->drawImage(bitmap.GetSkImage(), 0, 0, &paint);
+        if (alphaBitmap != nullptr)
+        {
+            paint.setBlendMode(SkBlendMode::kDstOut); // VCL alpha is one-minus-alpha
+            canvas->drawImage(alphaBitmap->GetAlphaSkImage(), 0, 0, &paint);
+        }
+        image = SkiaHelper::makeCheckedImageSnapshot(tmpSurface);
+    }
+    SkiaHelper::addCachedImage(key, image);
+    return image;
+}
+
+bool SkiaSalGraphicsImpl::drawAlphaBitmap(const SalTwoRect& rPosAry, const SalBitmap& rSourceBitmap,
+                                          const SalBitmap& rAlphaBitmap)
+{
+    assert(dynamic_cast<const SkiaSalBitmap*>(&rSourceBitmap));
+    assert(dynamic_cast<const SkiaSalBitmap*>(&rAlphaBitmap));
+    // In raster mode use mergeCacheBitmaps(), which will cache the result, avoiding repeated
+    // alpha blending or scaling. In GPU mode it is simpler to just use SkShader.
+    SalTwoRect imagePosAry(rPosAry);
+    Size imageSize = rSourceBitmap.GetSize();
+    // If the bitmap will be scaled, prefer to do it in mergeCacheBitmaps(), if possible.
+    if ((rPosAry.mnSrcWidth != rPosAry.mnDestWidth || rPosAry.mnSrcHeight != rPosAry.mnDestHeight)
+        && rPosAry.mnSrcX == 0 && rPosAry.mnSrcY == 0
+        && rPosAry.mnSrcWidth == rSourceBitmap.GetSize().Width()
+        && rPosAry.mnSrcHeight == rSourceBitmap.GetSize().Height())
+    {
+        imagePosAry.mnSrcWidth = imagePosAry.mnDestWidth;
+        imagePosAry.mnSrcHeight = imagePosAry.mnDestHeight;
+        imageSize = Size(imagePosAry.mnSrcWidth, imagePosAry.mnSrcHeight);
+    }
+    sk_sp<SkImage> image
+        = mergeCacheBitmaps(static_cast<const SkiaSalBitmap&>(rSourceBitmap),
+                            static_cast<const SkiaSalBitmap*>(&rAlphaBitmap), imageSize);
+    if (image)
+        drawImage(imagePosAry, image);
+    else
+        drawShader(
+            rPosAry,
+            SkShaders::Blend(
+                SkBlendMode::kDstOut, // VCL alpha is one-minus-alpha.
+                static_cast<const SkiaSalBitmap&>(rSourceBitmap).GetSkImage()->makeShader(),
+                static_cast<const SkiaSalBitmap*>(&rAlphaBitmap)->GetAlphaSkImage()->makeShader()));
+    return true;
+}
+
+void SkiaSalGraphicsImpl::drawImage(const SalTwoRect& rPosAry, const sk_sp<SkImage>& aImage,
+                                    SkBlendMode eBlendMode)
+{
+    SkRect aSourceRect
+        = SkRect::MakeXYWH(rPosAry.mnSrcX, rPosAry.mnSrcY, rPosAry.mnSrcWidth, rPosAry.mnSrcHeight);
+    SkRect aDestinationRect = SkRect::MakeXYWH(rPosAry.mnDestX, rPosAry.mnDestY,
+                                               rPosAry.mnDestWidth, rPosAry.mnDestHeight);
+
+    SkPaint aPaint;
+    aPaint.setBlendMode(eBlendMode);
+    if (rPosAry.mnSrcWidth != rPosAry.mnDestWidth || rPosAry.mnSrcHeight != rPosAry.mnDestHeight)
+        aPaint.setFilterQuality(kHigh_SkFilterQuality);
+
+    preDraw();
+    SAL_INFO("vcl.skia.trace",
+             "drawimage(" << this << "): " << rPosAry << ":" << SkBlendMode_Name(eBlendMode));
+    addXorRegion(aDestinationRect);
+    getDrawCanvas()->drawImageRect(aImage, aSourceRect, aDestinationRect, &aPaint);
+    postDraw();
+}
+
+// SkShader can be used to merge multiple bitmaps with appropriate blend modes (e.g. when
+// merging a bitmap with its alpha mask).
+void SkiaSalGraphicsImpl::drawShader(const SalTwoRect& rPosAry, const sk_sp<SkShader>& shader)
+{
+    preDraw();
+    SAL_INFO("vcl.skia.trace", "drawshader(" << this << "): " << rPosAry);
+    SkRect destinationRect = SkRect::MakeXYWH(rPosAry.mnDestX, rPosAry.mnDestY, rPosAry.mnDestWidth,
+                                              rPosAry.mnDestHeight);
+    addXorRegion(destinationRect);
+    SkPaint paint;
+    paint.setShader(shader);
+    if (rPosAry.mnSrcWidth != rPosAry.mnDestWidth || rPosAry.mnSrcHeight != rPosAry.mnDestHeight)
+        paint.setFilterQuality(kHigh_SkFilterQuality);
+    SkCanvas* canvas = getDrawCanvas();
+    // Scaling needs to be done explicitly using a matrix.
+    SkAutoCanvasRestore autoRestore(canvas, true);
+    SkMatrix matrix = SkMatrix::Translate(rPosAry.mnDestX, rPosAry.mnDestY)
+                      * SkMatrix::Scale(1.0 * rPosAry.mnDestWidth / rPosAry.mnSrcWidth,
+                                        1.0 * rPosAry.mnDestHeight / rPosAry.mnSrcHeight)
+                      * SkMatrix::Translate(-rPosAry.mnSrcX, -rPosAry.mnSrcY);
+    assert(matrix.mapXY(rPosAry.mnSrcX, rPosAry.mnSrcY)
+           == SkPoint::Make(rPosAry.mnDestX, rPosAry.mnDestY));
+    assert(matrix.mapXY(rPosAry.mnSrcX + rPosAry.mnSrcWidth, rPosAry.mnSrcY + rPosAry.mnSrcHeight)
+           == SkPoint::Make(rPosAry.mnDestX + rPosAry.mnDestWidth,
+                            rPosAry.mnDestY + rPosAry.mnDestHeight));
+    canvas->concat(matrix);
+    SkRect sourceRect
+        = SkRect::MakeXYWH(rPosAry.mnSrcX, rPosAry.mnSrcY, rPosAry.mnSrcWidth, rPosAry.mnSrcHeight);
+    canvas->drawRect(sourceRect, paint);
+    postDraw();
+}
+
+bool SkiaSalGraphicsImpl::drawTransformedBitmap(const basegfx::B2DPoint& rNull,
+                                                const basegfx::B2DPoint& rX,
+                                                const basegfx::B2DPoint& rY,
+                                                const SalBitmap& rSourceBitmap,
+                                                const SalBitmap* pAlphaBitmap)
+{
+    assert(dynamic_cast<const SkiaSalBitmap*>(&rSourceBitmap));
+    assert(!pAlphaBitmap || dynamic_cast<const SkiaSalBitmap*>(pAlphaBitmap));
+
+    const SkiaSalBitmap& rSkiaBitmap = static_cast<const SkiaSalBitmap&>(rSourceBitmap);
+    const SkiaSalBitmap* pSkiaAlphaBitmap = static_cast<const SkiaSalBitmap*>(pAlphaBitmap);
+
+    // Setup the image transformation,
+    // using the rNull, rX, rY points as destinations for the (0,0), (Width,0), (0,Height) source points.
+    const basegfx::B2DVector aXRel = rX - rNull;
+    const basegfx::B2DVector aYRel = rY - rNull;
+
+    preDraw();
+    SAL_INFO("vcl.skia.trace", "drawtransformedbitmap(" << this << "): " << rSourceBitmap.GetSize()
+                                                        << " " << rNull << ":" << rX << ":" << rY);
+
+    addXorRegion(SkRect::MakeWH(GetWidth(), GetHeight())); // can't tell, use whole area
+    // In raster mode scaling and alpha blending is still somewhat expensive if done repeatedly,
+    // so use mergeCacheBitmaps(), which will cache the result if useful.
+    // It is better to use SkShader if in GPU mode, if the operation is simple or if the temporary
+    // image would be very large.
+    sk_sp<SkImage> imageToDraw = mergeCacheBitmaps(
+        rSkiaBitmap, pSkiaAlphaBitmap, Size(round(aXRel.getLength()), round(aYRel.getLength())));
+    if (imageToDraw)
+    {
+        SkMatrix matrix;
+        // Round sizes for scaling, so that sub-pixel differences don't
+        // trigger unnecessary scaling. Image has already been scaled
+        // by mergeCacheBitmaps() and we shouldn't scale here again
+        // unless the drawing is also skewed.
+        matrix.set(SkMatrix::kMScaleX, round(aXRel.getX()) / imageToDraw->width());
+        matrix.set(SkMatrix::kMScaleY, round(aYRel.getY()) / imageToDraw->height());
+        matrix.set(SkMatrix::kMSkewY, aXRel.getY() / imageToDraw->width());
+        matrix.set(SkMatrix::kMSkewX, aYRel.getX() / imageToDraw->height());
+        matrix.set(SkMatrix::kMTransX, rNull.getX());
+        matrix.set(SkMatrix::kMTransY, rNull.getY());
+        SkCanvas* canvas = getDrawCanvas();
+        SkAutoCanvasRestore autoRestore(canvas, true);
+        canvas->concat(matrix);
+        SkPaint paint;
+        paint.setFilterQuality(kHigh_SkFilterQuality);
+        canvas->drawImage(imageToDraw, 0, 0, &paint);
+    }
+    else
+    {
+        SkMatrix matrix;
+        const Size aSize = rSourceBitmap.GetSize();
+        matrix.set(SkMatrix::kMScaleX, aXRel.getX() / aSize.Width());
+        matrix.set(SkMatrix::kMScaleY, aYRel.getY() / aSize.Height());
+        matrix.set(SkMatrix::kMSkewY, aXRel.getY() / aSize.Width());
+        matrix.set(SkMatrix::kMSkewX, aYRel.getX() / aSize.Height());
+        matrix.set(SkMatrix::kMTransX, rNull.getX());
+        matrix.set(SkMatrix::kMTransY, rNull.getY());
+        SkCanvas* canvas = getDrawCanvas();
+        SkAutoCanvasRestore autoRestore(canvas, true);
+        canvas->concat(matrix);
+        SkPaint paint;
+        paint.setFilterQuality(kHigh_SkFilterQuality);
+        if (pSkiaAlphaBitmap)
+        {
+            paint.setShader(SkShaders::Blend(SkBlendMode::kDstOut, // VCL alpha is one-minus-alpha.
+                                             rSkiaBitmap.GetSkImage()->makeShader(),
+                                             pSkiaAlphaBitmap->GetAlphaSkImage()->makeShader()));
+            canvas->drawRect(SkRect::MakeWH(aSize.Width(), aSize.Height()), paint);
+        }
+        else
+        {
+            canvas->drawImage(rSkiaBitmap.GetSkImage(), 0, 0, &paint);
+        }
+    }
+    postDraw();
+    return true;
+}
+
+bool SkiaSalGraphicsImpl::drawAlphaRect(long nX, long nY, long nWidth, long nHeight,
+                                        sal_uInt8 nTransparency)
+{
+    privateDrawAlphaRect(nX, nY, nWidth, nHeight, nTransparency / 100.0);
+    return true;
+}
+
+bool SkiaSalGraphicsImpl::drawGradient(const tools::PolyPolygon&, const Gradient&)
+{
+    // TODO?
+    return false;
+}
+
+static double toRadian(int degree10th) { return (3600 - degree10th) * M_PI / 1800.0; }
+static double toCos(int degree10th) { return SkScalarCos(toRadian(degree10th)); }
+static double toSin(int degree10th) { return SkScalarSin(toRadian(degree10th)); }
+
+void SkiaSalGraphicsImpl::drawGenericLayout(const GenericSalLayout& layout, Color textColor,
+                                            const SkFont& font, GlyphOrientation glyphOrientation)
+{
+    SkiaZone zone;
+    std::vector<SkGlyphID> glyphIds;
+    std::vector<SkRSXform> glyphForms;
+    glyphIds.reserve(256);
+    glyphForms.reserve(256);
+    Point aPos;
+    const GlyphItem* pGlyph;
+    int nStart = 0;
+    while (layout.GetNextGlyph(&pGlyph, aPos, nStart))
+    {
+        glyphIds.push_back(pGlyph->glyphId());
+        int angle = 0; // 10th of degree
+        if (glyphOrientation == GlyphOrientation::Apply)
+        {
+            angle = layout.GetOrientation();
+            if (pGlyph->IsVertical())
+                angle += 900; // 90 degree
+        }
+        SkRSXform form = SkRSXform::Make(toCos(angle), toSin(angle), aPos.X(), aPos.Y());
+        glyphForms.emplace_back(std::move(form));
+    }
+    if (glyphIds.empty())
+        return;
+    sk_sp<SkTextBlob> textBlob
+        = SkTextBlob::MakeFromRSXform(glyphIds.data(), glyphIds.size() * sizeof(SkGlyphID),
+                                      glyphForms.data(), font, SkTextEncoding::kGlyphID);
+    preDraw();
+    SAL_INFO("vcl.skia.trace",
+             "drawtextblob(" << this << "): " << textBlob->bounds() << ":" << textColor);
+    addXorRegion(textBlob->bounds());
+    SkPaint paint;
+    paint.setColor(toSkColor(textColor));
+    getDrawCanvas()->drawTextBlob(textBlob, 0, 0, paint);
+    postDraw();
+}
+
+bool SkiaSalGraphicsImpl::supportsOperation(OutDevSupportType eType) const
+{
+    switch (eType)
+    {
+        case OutDevSupportType::B2DDraw:
+        case OutDevSupportType::TransparentRect:
+            return true;
+        default:
+            return false;
+    }
+}
+
+#ifdef DBG_UTIL
+void SkiaSalGraphicsImpl::dump(const char* file) const
+{
+    assert(mSurface.get());
+    SkiaHelper::dump(mSurface, file);
+}
+#endif
+
+/* vim:set shiftwidth=4 softtabstop=4 expandtab: */
diff --git a/vcl/skia/salbmp.cxx b/vcl/skia/salbmp.cxx
new file mode 100644
index 000000000..0f62f7dc5
--- /dev/null
+++ b/vcl/skia/salbmp.cxx
@@ -0,0 +1,819 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/*
+ * This file is part of the LibreOffice project.
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ *
+ * This file incorporates work covered by the following license notice:
+ *
+ *   Licensed to the Apache Software Foundation (ASF) under one or more
+ *   contributor license agreements. See the NOTICE file distributed
+ *   with this work for additional information regarding copyright
+ *   ownership. The ASF licenses this file to you under the Apache
+ *   License, Version 2.0 (the "License"); you may not use this file
+ *   except in compliance with the License. You may obtain a copy of
+ *   the License at http://www.apache.org/licenses/LICENSE-2.0 .
+ */
+
+#include <skia/salbmp.hxx>
+
+#include <o3tl/safeint.hxx>
+#include <tools/helpers.hxx>
+#include <boost/smart_ptr/make_shared.hpp>
+
+#include <salgdi.hxx>
+#include <salinst.hxx>
+#include <scanlinewriter.hxx>
+#include <svdata.hxx>
+
+#include <SkCanvas.h>
+#include <SkImage.h>
+#include <SkPixelRef.h>
+#include <SkSurface.h>
+#include <SkSwizzle.h>
+#include <SkColorFilter.h>
+#include <SkColorMatrix.h>
+
+#include <skia/utils.hxx>
+#include <skia/zone.hxx>
+
+#ifdef DBG_UTIL
+#include <fstream>
+#define CANARY "skia-canary"
+#endif
+
+SkiaSalBitmap::SkiaSalBitmap() {}
+
+SkiaSalBitmap::~SkiaSalBitmap() {}
+
+static bool isValidBitCount(sal_uInt16 nBitCount)
+{
+    return (nBitCount == 1) || (nBitCount == 4) || (nBitCount == 8) || (nBitCount == 24)
+           || (nBitCount == 32);
+}
+
+SkiaSalBitmap::SkiaSalBitmap(const sk_sp<SkImage>& image)
+{
+    ResetCachedData();
+    mBuffer.reset();
+    mImage = image;
+    mPalette = BitmapPalette();
+    mBitCount = 32;
+    mSize = mPixelsSize = Size(image->width(), image->height());
+#ifdef DBG_UTIL
+    mWriteAccessCount = 0;
+#endif
+    SAL_INFO("vcl.skia.trace", "bitmapfromimage(" << this << ")");
+}
+
+bool SkiaSalBitmap::Create(const Size& rSize, sal_uInt16 nBitCount, const BitmapPalette& rPal)
+{
+    ResetCachedData();
+    mBuffer.reset();
+    if (!isValidBitCount(nBitCount))
+        return false;
+    mPalette = rPal;
+    mBitCount = nBitCount;
+    mSize = mPixelsSize = rSize;
+#ifdef DBG_UTIL
+    mWriteAccessCount = 0;
+#endif
+    if (!CreateBitmapData())
+    {
+        mBitCount = 0;
+        mSize = mPixelsSize = Size();
+        mPalette = BitmapPalette();
+        return false;
+    }
+    SAL_INFO("vcl.skia.trace", "create(" << this << ")");
+    return true;
+}
+
+bool SkiaSalBitmap::CreateBitmapData()
+{
+    assert(!mBuffer);
+    // The pixels could be stored in SkBitmap, but Skia only supports 8bit gray, 16bit and 32bit formats
+    // (e.g. 24bpp is actually stored as 32bpp). But some of our code accessing the bitmap assumes that
+    // when it asked for 24bpp, the format really will be 24bpp (e.g. the png loader), so we cannot use
+    // SkBitmap to store the data. And even 8bpp is problematic, since Skia does not support palettes
+    // and a VCL bitmap can change its grayscale status simply by changing the palette.
+    // Moreover creating SkImage from SkBitmap does a data copy unless the bitmap is immutable.
+    // So just always store pixels in our buffer and convert as necessary.
+    int bitScanlineWidth;
+    if (o3tl::checked_multiply<int>(mSize.Width(), mBitCount, bitScanlineWidth))
+    {
+        SAL_WARN("vcl.skia", "checked multiply failed");
+        return false;
+    }
+    mScanlineSize = AlignedWidth4Bytes(bitScanlineWidth);
+    if (mScanlineSize != 0 && mSize.Height() != 0)
+    {
+        size_t allocate = mScanlineSize * mSize.Height();
+#ifdef DBG_UTIL
+        allocate += sizeof(CANARY);
+#endif
+        mBuffer = boost::make_shared_noinit<sal_uInt8[]>(allocate);
+#ifdef DBG_UTIL
+        // fill with random garbage
+        sal_uInt8* buffer = mBuffer.get();
+        for (size_t i = 0; i < allocate; i++)
+            buffer[i] = (i & 0xFF);
+        memcpy(buffer + allocate - sizeof(CANARY), CANARY, sizeof(CANARY));
+#endif
+    }
+    return true;
+}
+
+bool SkiaSalBitmap::Create(const SalBitmap& rSalBmp)
+{
+    return Create(rSalBmp, rSalBmp.GetBitCount());
+}
+
+bool SkiaSalBitmap::Create(const SalBitmap& rSalBmp, SalGraphics* pGraphics)
+{
+    return Create(rSalBmp, pGraphics ? pGraphics->GetBitCount() : rSalBmp.GetBitCount());
+}
+
+bool SkiaSalBitmap::Create(const SalBitmap& rSalBmp, sal_uInt16 nNewBitCount)
+{
+    const SkiaSalBitmap& src = static_cast<const SkiaSalBitmap&>(rSalBmp);
+    mImage = src.mImage;
+    mAlphaImage = src.mAlphaImage;
+    mBuffer = src.mBuffer;
+    mPalette = src.mPalette;
+    mBitCount = src.mBitCount;
+    mSize = src.mSize;
+    mPixelsSize = src.mPixelsSize;
+    mScanlineSize = src.mScanlineSize;
+    mScaleQuality = src.mScaleQuality;
+#ifdef DBG_UTIL
+    mWriteAccessCount = 0;
+#endif
+    if (nNewBitCount != src.GetBitCount())
+    {
+        // This appears to be unused(?). Implement this just in case, but be lazy
+        // about it and rely on EnsureBitmapData() doing the conversion from mImage
+        // if needed, even if that may need unnecessary to- and from- SkImage
+        // conversion.
+        ResetToSkImage(GetSkImage());
+    }
+    SAL_INFO("vcl.skia.trace", "create(" << this << "): (" << &src << ")");
+    return true;
+}
+
+bool SkiaSalBitmap::Create(const css::uno::Reference<css::rendering::XBitmapCanvas>&, Size&, bool)
+{
+    // TODO?
+    return false;
+}
+
+void SkiaSalBitmap::Destroy()
+{
+    SAL_INFO("vcl.skia.trace", "destroy(" << this << ")");
+#ifdef DBG_UTIL
+    assert(mWriteAccessCount == 0);
+#endif
+    ResetCachedData();
+    mBuffer.reset();
+}
+
+Size SkiaSalBitmap::GetSize() const { return mSize; }
+
+sal_uInt16 SkiaSalBitmap::GetBitCount() const { return mBitCount; }
+
+BitmapBuffer* SkiaSalBitmap::AcquireBuffer(BitmapAccessMode nMode)
+{
+    switch (nMode)
+    {
+        case BitmapAccessMode::Write:
+            EnsureBitmapUniqueData();
+            if (!mBuffer)
+                return nullptr;
+            break;
+        case BitmapAccessMode::Read:
+            EnsureBitmapData();
+            if (!mBuffer)
+                return nullptr;
+            break;
+        case BitmapAccessMode::Info:
+            break;
+    }
+#ifdef DBG_UTIL
+    // BitmapWriteAccess stores also a copy of the palette and it can
+    // be modified, so concurrent reading of it might result in inconsistencies.
+    assert(mWriteAccessCount == 0 || nMode == BitmapAccessMode::Write);
+#endif
+    BitmapBuffer* buffer = new BitmapBuffer;
+    buffer->mnWidth = mSize.Width();
+    buffer->mnHeight = mSize.Height();
+    buffer->mnBitCount = mBitCount;
+    buffer->maPalette = mPalette;
+    buffer->mpBits = mBuffer.get();
+    buffer->mnScanlineSize = mScanlineSize;
+    switch (mBitCount)
+    {
+        case 1:
+            buffer->mnFormat = ScanlineFormat::N1BitMsbPal;
+            break;
+        case 4:
+            buffer->mnFormat = ScanlineFormat::N4BitMsnPal;
+            break;
+        case 8:
+            buffer->mnFormat = ScanlineFormat::N8BitPal;
+            break;
+        case 24:
+        {
+// Make the RGB/BGR format match the default Skia 32bpp format, to allow
+// easy conversion later.
+// Use a macro to hide an unreachable code warning.
+#define GET_FORMAT                                                                                 \
+    (kN32_SkColorType == kBGRA_8888_SkColorType ? ScanlineFormat::N24BitTcBgr                      \
+                                                : ScanlineFormat::N24BitTcRgb)
+            buffer->mnFormat = GET_FORMAT;
+#undef GET_FORMAT
+            break;
+        }
+        case 32:
+#define GET_FORMAT                                                                                 \
+    (kN32_SkColorType == kBGRA_8888_SkColorType ? ScanlineFormat::N32BitTcBgra                     \
+                                                : ScanlineFormat::N32BitTcRgba)
+            buffer->mnFormat = GET_FORMAT;
+#undef GET_FORMAT
+            break;
+        default:
+            abort();
+    }
+    buffer->mnFormat |= ScanlineFormat::TopDown;
+#ifdef DBG_UTIL
+    if (nMode == BitmapAccessMode::Write)
+        ++mWriteAccessCount;
+#endif
+    return buffer;
+}
+
+void SkiaSalBitmap::ReleaseBuffer(BitmapBuffer* pBuffer, BitmapAccessMode nMode)
+{
+    if (nMode == BitmapAccessMode::Write)
+    {
+#ifdef DBG_UTIL
+        assert(mWriteAccessCount > 0);
+        --mWriteAccessCount;
+#endif
+        mPalette = pBuffer->maPalette;
+        ResetCachedData();
+    }
+    // Are there any more ground movements underneath us ?
+    assert(pBuffer->mnWidth == mSize.Width());
+    assert(pBuffer->mnHeight == mSize.Height());
+    assert(pBuffer->mnBitCount == mBitCount);
+    verify();
+    delete pBuffer;
+}
+
+bool SkiaSalBitmap::GetSystemData(BitmapSystemData&)
+{
+#ifdef DBG_UTIL
+    assert(mWriteAccessCount == 0);
+#endif
+    // TODO?
+    return false;
+}
+
+bool SkiaSalBitmap::ScalingSupported() const { return true; }
+
+bool SkiaSalBitmap::Scale(const double& rScaleX, const double& rScaleY, BmpScaleFlag nScaleFlag)
+{
+    SkiaZone zone;
+#ifdef DBG_UTIL
+    assert(mWriteAccessCount == 0);
+#endif
+    Size newSize(FRound(mSize.Width() * rScaleX), FRound(mSize.Height() * rScaleY));
+    if (mSize == newSize)
+        return true;
+
+    SAL_INFO("vcl.skia.trace", "scale(" << this << "): " << mSize << "/" << mBitCount << "->"
+                                        << newSize << ":" << static_cast<int>(nScaleFlag));
+
+    // The idea here is that the actual scaling will be delayed until the result
+    // is actually needed. Usually the scaled bitmap will be drawn somewhere,
+    // so delaying will mean the scaling can be done as a part of GetSkImage().
+    // That means it can be GPU-accelerated, while done here directly it would need
+    // to be either done by CPU, or with the CPU->GPU->CPU roundtrip required
+    // by GPU-accelerated scaling.
+    // Pending scaling is detected by 'mSize != mPixelsSize'.
+    SkFilterQuality currentQuality;
+    switch (nScaleFlag)
+    {
+        case BmpScaleFlag::Fast:
+            currentQuality = kNone_SkFilterQuality;
+            break;
+        case BmpScaleFlag::Default:
+            currentQuality = kMedium_SkFilterQuality;
+            break;
+        case BmpScaleFlag::BestQuality:
+            currentQuality = kHigh_SkFilterQuality;
+            break;
+        default:
+            SAL_INFO("vcl.skia.trace", "scale(" << this << "): unsupported scale algorithm");
+            return false;
+    }
+    if (mBitCount < 24 && !mPalette.IsGreyPalette8Bit())
+    {
+        // Scaling can introduce additional colors not present in the original
+        // bitmap (e.g. when smoothing). If the bitmap is indexed (has non-trivial palette),
+        // this would break the bitmap, because the actual scaling is done only somewhen later.
+        // Linear 8bit palette (grey) is ok, since there we use directly the values as colors.
+        SAL_INFO("vcl.skia.trace", "scale(" << this << "): indexed bitmap");
+        return false;
+    }
+    // if there is already one scale() pending, use the lowest quality of all requested
+    static_assert(kMedium_SkFilterQuality < kHigh_SkFilterQuality);
+    mScaleQuality = std::min(mScaleQuality, currentQuality);
+    // scaling will be actually done on-demand when needed, the need will be recognized
+    // by mSize != mPixelsSize
+    mSize = newSize;
+    // Do not reset cached data if mImage is possibly the only data we have.
+    if (mBuffer)
+        ResetCachedData();
+    // The rest will be handled when the scaled bitmap is actually needed,
+    // such as in EnsureBitmapData() or GetSkImage().
+    return true;
+}
+
+bool SkiaSalBitmap::Replace(const Color&, const Color&, sal_uInt8)
+{
+#ifdef DBG_UTIL
+    assert(mWriteAccessCount == 0);
+#endif
+    // TODO?
+    return false;
+}
+
+bool SkiaSalBitmap::ConvertToGreyscale()
+{
+#ifdef DBG_UTIL
+    assert(mWriteAccessCount == 0);
+#endif
+    // Normally this would need to convert contents of mBuffer for all possible formats,
+    // so just let the VCL algorithm do it.
+    // Avoid the costly SkImage->buffer->SkImage conversion.
+    if (!mBuffer && mImage)
+    {
+        if (mBitCount == 8 && mPalette.IsGreyPalette8Bit())
+            return true;
+        sk_sp<SkSurface> surface = SkiaHelper::createSkSurface(mPixelsSize);
+        SkPaint paint;
+        paint.setBlendMode(SkBlendMode::kSrc); // set as is, including alpha
+        // VCL uses different coefficients for conversion to gray than Skia, so use the VCL
+        // values from Bitmap::ImplMakeGreyscales(). Do not use kGray_8_SkColorType,
+        // Skia would use its gray conversion formula.
+        // NOTE: The matrix is 4x5 organized as columns (i.e. each line is a column, not a row).
+        constexpr SkColorMatrix toGray(77 / 256.0, 151 / 256.0, 28 / 256.0, 0, 0, // R column
+                                       77 / 256.0, 151 / 256.0, 28 / 256.0, 0, 0, // G column
+                                       77 / 256.0, 151 / 256.0, 28 / 256.0, 0, 0, // B column
+                                       0, 0, 0, 1, 0); // don't modify alpha
+        paint.setColorFilter(SkColorFilters::Matrix(toGray));
+        surface->getCanvas()->drawImage(mImage, 0, 0, &paint);
+        mBitCount = 8;
+        mPalette = Bitmap::GetGreyPalette(256);
+        ResetToSkImage(SkiaHelper::makeCheckedImageSnapshot(surface));
+        SAL_INFO("vcl.skia.trace", "converttogreyscale(" << this << ")");
+        return true;
+    }
+    return false;
+}
+
+bool SkiaSalBitmap::InterpretAs8Bit()
+{
+#ifdef DBG_UTIL
+    assert(mWriteAccessCount == 0);
+#endif
+    if (mBitCount == 8 && mPalette.IsGreyPalette8Bit())
+        return true;
+    // This is usually used by AlphaMask, the point is just to treat
+    // the content as an alpha channel. This is often used
+    // by the horrible separate-alpha-outdev hack, where the bitmap comes
+    // from SkiaSalGraphicsImpl::GetBitmap(), so only mImage is set,
+    // and that is followed by a later call to GetAlphaSkImage().
+    // Avoid the costly SkImage->buffer->SkImage conversion and simply
+    // just treat the SkImage as being for 8bit bitmap. EnsureBitmapData()
+    // will do the conversion if needed, but the normal case will be
+    // GetAlphaSkImage() creating kAlpha_8_SkColorType SkImage from it.
+    if (!mBuffer && mImage)
+    {
+        mBitCount = 8;
+        mPalette = Bitmap::GetGreyPalette(256);
+        ResetToSkImage(mImage); // keep mImage, it will be interpreted as 8bit if needed
+        SAL_INFO("vcl.skia.trace", "interpretas8bit(" << this << ")");
+        return true;
+    }
+    return false;
+}
+
+SkBitmap SkiaSalBitmap::GetAsSkBitmap() const
+{
+#ifdef DBG_UTIL
+    assert(mWriteAccessCount == 0);
+#endif
+    EnsureBitmapData();
+    assert(mSize == mPixelsSize); // data has already been scaled if needed
+    SkiaZone zone;
+    SkBitmap bitmap;
+    if (mBuffer)
+    {
+        if (mBitCount == 32)
+        {
+            // Make a copy, the bitmap should be immutable (otherwise converting it
+            // to SkImage will make a copy anyway).
+            const size_t bytes = mPixelsSize.Height() * mScanlineSize;
+            std::unique_ptr<sal_uInt8[]> data(new sal_uInt8[bytes]);
+            memcpy(data.get(), mBuffer.get(), bytes);
+#if SKIA_USE_BITMAP32
+            SkAlphaType alphaType = kPremul_SkAlphaType;
+#else
+            SkAlphaType alphaType = kUnpremul_SkAlphaType;
+#endif
+            if (!bitmap.installPixels(
+                    SkImageInfo::MakeS32(mPixelsSize.Width(), mPixelsSize.Height(), alphaType),
+                    data.release(), mPixelsSize.Width() * 4,
+                    [](void* addr, void*) { delete[] static_cast<sal_uInt8*>(addr); }, nullptr))
+                abort();
+            bitmap.setImmutable();
+        }
+        else if (mBitCount == 24)
+        {
+            // Convert 24bpp RGB/BGR to 32bpp RGBA/BGRA.
+            std::unique_ptr<uint32_t[]> data(
+                new uint32_t[mPixelsSize.Height() * mPixelsSize.Width()]);
+            uint32_t* dest = data.get();
+            for (long y = 0; y < mPixelsSize.Height(); ++y)
+            {
+                const sal_uInt8* src = mBuffer.get() + mScanlineSize * y;
+                // This also works as BGR to BGRA (the function extends 3 bytes to 4
+                // by adding 0xFF alpha, so position of B and R doesn't matter).
+                SkExtendRGBToRGBA(dest, src, mPixelsSize.Width());
+                dest += mPixelsSize.Width();
+            }
+            if (!bitmap.installPixels(
+                    SkImageInfo::MakeS32(mPixelsSize.Width(), mPixelsSize.Height(),
+                                         kOpaque_SkAlphaType),
+                    data.release(), mPixelsSize.Width() * 4,
+                    [](void* addr, void*) { delete[] static_cast<sal_uInt8*>(addr); }, nullptr))
+                abort();
+            bitmap.setImmutable();
+        }
+        // Skia has a format for 8bit grayscale SkBitmap, but it seems to cause a problem
+        // with our PNG loader (tdf#121120), so convert it to RGBA below as well.
+        else
+        {
+// Use a macro to hide an unreachable code warning.
+#define GET_FORMAT                                                                                 \
+    (kN32_SkColorType == kBGRA_8888_SkColorType ? BitConvert::BGRA : BitConvert::RGBA)
+            std::unique_ptr<sal_uInt8[]> data
+                = convertDataBitCount(mBuffer.get(), mPixelsSize.Width(), mPixelsSize.Height(),
+                                      mBitCount, mScanlineSize, mPalette, GET_FORMAT);
+#undef GET_FORMAT
+            if (!bitmap.installPixels(
+                    SkImageInfo::MakeS32(mPixelsSize.Width(), mPixelsSize.Height(),
+                                         kOpaque_SkAlphaType),
+                    data.release(), mPixelsSize.Width() * 4,
+                    [](void* addr, void*) { delete[] static_cast<sal_uInt8*>(addr); }, nullptr))
+                abort();
+            bitmap.setImmutable();
+        }
+    }
+    return bitmap;
+}
+
+const sk_sp<SkImage>& SkiaSalBitmap::GetSkImage() const
+{
+#ifdef DBG_UTIL
+    assert(mWriteAccessCount == 0);
+#endif
+    if (mPixelsSize != mSize && !mImage
+        && SkiaHelper::renderMethodToUse() != SkiaHelper::RenderRaster)
+    {
+        // The bitmap has a pending scaling, but no image. This function would below call GetAsSkBitmap(),
+        // which would do CPU-based pixel scaling, and then it would get converted to an image.
+        // Be more efficient, first convert to an image and then the block below will scale on the GPU.
+        SAL_INFO("vcl.skia.trace", "getskimage(" << this << "): shortcut image scaling "
+                                                 << mPixelsSize << "->" << mSize);
+        SkiaSalBitmap* thisPtr = const_cast<SkiaSalBitmap*>(this);
+        Size savedSize = mSize;
+        thisPtr->mSize = mPixelsSize; // block scaling
+        SkiaZone zone;
+        sk_sp<SkImage> image = SkiaHelper::createSkImage(GetAsSkBitmap());
+        assert(image);
+        thisPtr->mSize = savedSize;
+        thisPtr->ResetToSkImage(image);
+    }
+    if (mImage)
+    {
+        if (mImage->width() != mSize.Width() || mImage->height() != mSize.Height())
+        {
+            assert(!mBuffer); // This code should be only called if only mImage holds data.
+            SkiaZone zone;
+            sk_sp<SkSurface> surface = SkiaHelper::createSkSurface(mSize);
+            assert(surface);
+            SkPaint paint;
+            paint.setBlendMode(SkBlendMode::kSrc); // set as is, including alpha
+            paint.setFilterQuality(mScaleQuality);
+            surface->getCanvas()->drawImageRect(
+                mImage, SkRect::MakeWH(mImage->width(), mImage->height()),
+                SkRect::MakeWH(mSize.Width(), mSize.Height()), &paint);
+            SAL_INFO("vcl.skia.trace", "getskimage(" << this << "): image scaled "
+                                                     << Size(mImage->width(), mImage->height())
+                                                     << "->" << mSize << ":"
+                                                     << static_cast<int>(mScaleQuality));
+            SkiaSalBitmap* thisPtr = const_cast<SkiaSalBitmap*>(this);
+            thisPtr->mImage = SkiaHelper::makeCheckedImageSnapshot(surface);
+        }
+        return mImage;
+    }
+    SkiaZone zone;
+    sk_sp<SkImage> image = SkiaHelper::createSkImage(GetAsSkBitmap());
+    assert(image);
+    const_cast<sk_sp<SkImage>&>(mImage) = image;
+    SAL_INFO("vcl.skia.trace", "getskimage(" << this << ")");
+    return mImage;
+}
+
+const sk_sp<SkImage>& SkiaSalBitmap::GetAlphaSkImage() const
+{
+#ifdef DBG_UTIL
+    assert(mWriteAccessCount == 0);
+#endif
+    if (mAlphaImage)
+    {
+        assert(mSize == mPixelsSize); // data has already been scaled if needed
+        return mAlphaImage;
+    }
+    if (mImage)
+    {
+        SkiaZone zone;
+        sk_sp<SkSurface> surface = SkiaHelper::createSkSurface(mSize, kAlpha_8_SkColorType);
+        assert(surface);
+        SkPaint paint;
+        paint.setBlendMode(SkBlendMode::kSrc); // set as is, including alpha
+        // Move the R channel value to the alpha channel. This seems to be the only
+        // way to reinterpret data in SkImage as an alpha SkImage without accessing the pixels.
+        // NOTE: The matrix is 4x5 organized as columns (i.e. each line is a column, not a row).
+        constexpr SkColorMatrix redToAlpha(0, 0, 0, 0, 0, // R column
+                                           0, 0, 0, 0, 0, // G column
+                                           0, 0, 0, 0, 0, // B column
+                                           1, 0, 0, 0, 0); // A column
+        paint.setColorFilter(SkColorFilters::Matrix(redToAlpha));
+        bool scaling = mImage->width() != mSize.Width() || mImage->height() != mSize.Height();
+        if (scaling)
+        {
+            assert(!mBuffer); // This code should be only called if only mImage holds data.
+            paint.setFilterQuality(mScaleQuality);
+        }
+        surface->getCanvas()->drawImageRect(mImage,
+                                            SkRect::MakeWH(mImage->width(), mImage->height()),
+                                            SkRect::MakeWH(mSize.Width(), mSize.Height()), &paint);
+        if (scaling)
+            SAL_INFO("vcl.skia.trace", "getalphaskimage(" << this << "): image scaled "
+                                                          << Size(mImage->width(), mImage->height())
+                                                          << "->" << mSize << ":"
+                                                          << static_cast<int>(mScaleQuality));
+        else
+            SAL_INFO("vcl.skia.trace", "getalphaskimage(" << this << ") from image");
+        SkiaSalBitmap* thisPtr = const_cast<SkiaSalBitmap*>(this);
+        thisPtr->mAlphaImage = SkiaHelper::makeCheckedImageSnapshot(surface);
+        return mAlphaImage;
+    }
+    SkiaZone zone;
+    EnsureBitmapData();
+    assert(mSize == mPixelsSize); // data has already been scaled if needed
+    SkBitmap alphaBitmap;
+    if (mBuffer && mBitCount <= 8)
+    {
+        assert(mBuffer.get());
+        verify();
+        std::unique_ptr<sal_uInt8[]> data
+            = convertDataBitCount(mBuffer.get(), mSize.Width(), mSize.Height(), mBitCount,
+                                  mScanlineSize, mPalette, BitConvert::A8);
+        if (!alphaBitmap.installPixels(
+                SkImageInfo::MakeA8(mSize.Width(), mSize.Height()), data.release(), mSize.Width(),
+                [](void* addr, void*) { delete[] static_cast<sal_uInt8*>(addr); }, nullptr))
+            abort();
+        alphaBitmap.setImmutable();
+        sk_sp<SkImage> image = SkiaHelper::createSkImage(alphaBitmap);
+        assert(image);
+        const_cast<sk_sp<SkImage>&>(mAlphaImage) = image;
+    }
+    else
+    {
+        sk_sp<SkSurface> surface = SkiaHelper::createSkSurface(mSize, kAlpha_8_SkColorType);
+        assert(surface);
+        SkPaint paint;
+        paint.setBlendMode(SkBlendMode::kSrc); // set as is, including alpha
+        // Move the R channel value to the alpha channel. This seems to be the only
+        // way to reinterpret data in SkImage as an alpha SkImage without accessing the pixels.
+        // NOTE: The matrix is 4x5 organized as columns (i.e. each line is a column, not a row).
+        constexpr SkColorMatrix redToAlpha(0, 0, 0, 0, 0, // R column
+                                           0, 0, 0, 0, 0, // G column
+                                           0, 0, 0, 0, 0, // B column
+                                           1, 0, 0, 0, 0); // A column
+        paint.setColorFilter(SkColorFilters::Matrix(redToAlpha));
+        surface->getCanvas()->drawBitmap(GetAsSkBitmap(), 0, 0, &paint);
+        SkiaSalBitmap* thisPtr = const_cast<SkiaSalBitmap*>(this);
+        thisPtr->mAlphaImage = SkiaHelper::makeCheckedImageSnapshot(surface);
+    }
+    SAL_INFO("vcl.skia.trace", "getalphaskimage(" << this << ")");
+    return mAlphaImage;
+}
+
+void SkiaSalBitmap::EnsureBitmapData()
+{
+    if (mBuffer)
+    {
+        if (mSize == mPixelsSize)
+            return;
+        // Pending scaling. Create raster SkImage from the bitmap data
+        // at the pixel size and then the code below will scale at the correct
+        // bpp from the image.
+        SAL_INFO("vcl.skia.trace", "ensurebitmapdata(" << this << "): pixels to be scaled "
+                                                       << mPixelsSize << "->" << mSize << ":"
+                                                       << static_cast<int>(mScaleQuality));
+        Size savedSize = mSize;
+        mSize = mPixelsSize;
+        ResetToSkImage(SkImage::MakeFromBitmap(GetAsSkBitmap()));
+        mSize = savedSize;
+    }
+    // Try to fill mBuffer from mImage.
+    if (!mImage)
+        return;
+    SkiaZone zone;
+    if (!CreateBitmapData())
+        abort();
+    SkAlphaType alphaType = kUnpremul_SkAlphaType;
+#if SKIA_USE_BITMAP32
+    if (mBitCount == 32)
+        alphaType = kPremul_SkAlphaType;
+#endif
+    SkBitmap bitmap;
+    if (!bitmap.tryAllocPixels(SkImageInfo::MakeS32(mSize.Width(), mSize.Height(), alphaType)))
+        abort();
+    SkCanvas canvas(bitmap);
+    SkPaint paint;
+    paint.setBlendMode(SkBlendMode::kSrc); // set as is, including alpha
+    if (mSize != mPixelsSize) // pending scaling?
+    {
+        paint.setFilterQuality(mScaleQuality);
+        canvas.drawImageRect(mImage,
+                             SkRect::MakeWH(mPixelsSize.getWidth(), mPixelsSize.getHeight()),
+                             SkRect::MakeWH(mSize.getWidth(), mSize.getHeight()), &paint);
+        SAL_INFO("vcl.skia.trace", "ensurebitmapdata(" << this << "): image scaled " << mPixelsSize
+                                                       << "->" << mSize << ":"
+                                                       << static_cast<int>(mScaleQuality));
+        mPixelsSize = mSize;
+        mScaleQuality = kHigh_SkFilterQuality;
+        // Information about the pending scaling has been discarded, so make sure we do not
+        // keep around any cached images that would still need scaling.
+        ResetCachedDataBySize();
+    }
+    else
+        canvas.drawImage(mImage, 0, 0, &paint);
+    canvas.flush();
+    bitmap.setImmutable();
+    assert(mBuffer != nullptr);
+    if (mBitCount == 32)
+    {
+        for (long y = 0; y < mSize.Height(); ++y)
+        {
+            const uint8_t* src = static_cast<uint8_t*>(bitmap.getAddr(0, y));
+            sal_uInt8* dest = mBuffer.get() + mScanlineSize * y;
+            memcpy(dest, src, mScanlineSize);
+        }
+    }
+    else if (mBitCount == 24) // non-paletted
+    {
+        for (long y = 0; y < mSize.Height(); ++y)
+        {
+            const uint8_t* src = static_cast<uint8_t*>(bitmap.getAddr(0, y));
+            sal_uInt8* dest = mBuffer.get() + mScanlineSize * y;
+            for (long x = 0; x < mSize.Width(); ++x)
+            {
+                *dest++ = *src++;
+                *dest++ = *src++;
+                *dest++ = *src++;
+                ++src; // skip alpha
+            }
+        }
+    }
+    else if (mBitCount == 8 && mPalette.IsGreyPalette8Bit())
+    {
+        for (long y = 0; y < mSize.Height(); ++y)
+        {
+            const uint8_t* src = static_cast<uint8_t*>(bitmap.getAddr(0, y));
+            sal_uInt8* dest = mBuffer.get() + mScanlineSize * y;
+            // no actual data conversion, use one color channel as the gray value
+            for (long x = 0; x < mSize.Width(); ++x)
+                dest[x] = src[x * 4];
+        }
+    }
+    else
+    {
+        std::unique_ptr<vcl::ScanlineWriter> pWriter
+            = vcl::ScanlineWriter::Create(mBitCount, mPalette);
+        for (long y = 0; y < mSize.Height(); ++y)
+        {
+            const uint8_t* src = static_cast<uint8_t*>(bitmap.getAddr(0, y));
+            sal_uInt8* dest = mBuffer.get() + mScanlineSize * y;
+            pWriter->nextLine(dest);
+            for (long x = 0; x < mSize.Width(); ++x)
+            {
+                sal_uInt8 r = *src++;
+                sal_uInt8 g = *src++;
+                sal_uInt8 b = *src++;
+                ++src; // skip alpha
+                pWriter->writeRGB(r, g, b);
+            }
+        }
+    }
+    verify();
+    SAL_INFO("vcl.skia.trace", "ensurebitmapdata(" << this << ")");
+}
+
+void SkiaSalBitmap::EnsureBitmapUniqueData()
+{
+    EnsureBitmapData();
+    if (mBuffer.use_count() > 1)
+    {
+        sal_uInt32 allocate = mScanlineSize * mSize.Height();
+#ifdef DBG_UTIL
+        assert(memcmp(mBuffer.get() + allocate, CANARY, sizeof(CANARY)) == 0);
+        allocate += sizeof(CANARY);
+#endif
+        boost::shared_ptr<sal_uInt8[]> newBuffer = boost::make_shared_noinit<sal_uInt8[]>(allocate);
+        memcpy(newBuffer.get(), mBuffer.get(), allocate);
+        mBuffer = newBuffer;
+    }
+}
+
+void SkiaSalBitmap::ResetCachedData()
+{
+    SkiaZone zone;
+    // There may be a case when only mImage is set and CreatBitmapData() will create
+    // mBuffer from it if needed, in that case ResetToSkImage() should be used.
+    assert(mBuffer.get() || !mImage);
+    mImage.reset();
+    mAlphaImage.reset();
+}
+
+void SkiaSalBitmap::ResetToSkImage(sk_sp<SkImage> image)
+{
+    SkiaZone zone;
+    mBuffer.reset();
+    mImage = image;
+    mAlphaImage.reset();
+}
+
+void SkiaSalBitmap::ResetCachedDataBySize()
+{
+    SkiaZone zone;
+    assert(mSize == mPixelsSize);
+    if (mImage && (mImage->width() != mSize.getWidth() || mImage->height() != mSize.getHeight()))
+        mImage.reset();
+    if (mAlphaImage
+        && (mAlphaImage->width() != mSize.getWidth() || mAlphaImage->height() != mSize.getHeight()))
+        mAlphaImage.reset();
+}
+
+#ifdef DBG_UTIL
+void SkiaSalBitmap::dump(const char* file) const
+{
+    sk_sp<SkImage> saveImage = mImage;
+    sk_sp<SkImage> saveAlphaImage = mAlphaImage;
+    bool resetBuffer = !mBuffer;
+    int saveWriteAccessCount = mWriteAccessCount;
+    Size savePrescaleSize = mPixelsSize;
+    SkiaSalBitmap* thisPtr = const_cast<SkiaSalBitmap*>(this);
+    // avoid possible assert
+    thisPtr->mWriteAccessCount = 0;
+    SkiaHelper::dump(GetSkImage(), file);
+    // restore old state, so that debugging doesn't affect it
+    if (resetBuffer)
+        thisPtr->mBuffer.reset();
+    thisPtr->mImage = saveImage;
+    thisPtr->mAlphaImage = saveAlphaImage;
+    thisPtr->mWriteAccessCount = saveWriteAccessCount;
+    thisPtr->mPixelsSize = savePrescaleSize;
+}
+
+void SkiaSalBitmap::verify() const
+{
+    if (!mBuffer)
+        return;
+    // Use mPixelsSize, that describes the size of the actual data.
+    assert(memcmp(mBuffer.get() + mScanlineSize * mPixelsSize.Height(), CANARY, sizeof(CANARY))
+           == 0);
+}
+
+#endif
+
+/* vim:set shiftwidth=4 softtabstop=4 expandtab: */
diff --git a/vcl/skia/skia_blacklist_vulkan.xml b/vcl/skia/skia_blacklist_vulkan.xml
new file mode 100644
index 000000000..8a222d005
--- /dev/null
+++ b/vcl/skia/skia_blacklist_vulkan.xml
@@ -0,0 +1,37 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!--
+* This file is part of the LibreOffice project.
+*
+* This Source Code Form is subject to the terms of the Mozilla Public
+* License, v. 2.0. If a copy of the MPL was not distributed with this
+* file, You can obtain one at http://mozilla.org/MPL/2.0/.
+-->
+
+<!--
+    entry attributes:
+    os - "all", "7", "8", "8_1", "10", "windows", "linux", "osx_10_5", "osx_10_6", "osx_10_7", "osx_10_8", "osx"
+    vendor - "all", "intel", "amd", "nvidia", "microsoft"
+    compare - "less", "less_equal", "greater", "greater_equal", "equal", "not_equal", "between_exclusive", "between_inclusive", "between_inclusive_start"
+    version
+    minVersion
+    maxVersion
+-->
+
+<root>
+    <whitelist>
+    </whitelist>
+    <blacklist>
+        <entry os="all" vendor="intel" compare="less_equal" version="0.16.2">
+            <device id="all"/>
+        </entry>
+        <entry os="all" vendor="amd" compare="less_equal" version="2.0.49">
+            <device id="all"/>
+        </entry>
+        <entry os="windows" vendor="nvidia">
+            <device id="all"/>
+        </entry>
+        <entry os="7" vendor="all">
+            <device id="all"/>
+        </entry>
+    </blacklist>
+</root>
diff --git a/vcl/skia/win/gdiimpl.cxx b/vcl/skia/win/gdiimpl.cxx
new file mode 100644
index 000000000..a4cbe062f
--- /dev/null
+++ b/vcl/skia/win/gdiimpl.cxx
@@ -0,0 +1,393 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/*
+ * This file is part of the LibreOffice project.
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ */
+
+#include <skia/win/gdiimpl.hxx>
+
+#include <win/saldata.hxx>
+#include <vcl/skia/SkiaHelper.hxx>
+#include <skia/utils.hxx>
+#include <skia/zone.hxx>
+#include <win/winlayout.hxx>
+#include <comphelper/windowserrorstring.hxx>
+
+#include <SkCanvas.h>
+#include <SkPaint.h>
+#include <SkPixelRef.h>
+#include <SkTypeface_win.h>
+#include <SkFont.h>
+#include <SkFontMgr.h>
+#include <SkFontLCDConfig.h>
+#include <tools/sk_app/win/WindowContextFactory_win.h>
+#include <tools/sk_app/WindowContext.h>
+
+#include <windows.h>
+
+WinSkiaSalGraphicsImpl::WinSkiaSalGraphicsImpl(WinSalGraphics& rGraphics,
+                                               SalGeometryProvider* mpProvider)
+    : SkiaSalGraphicsImpl(rGraphics, mpProvider)
+    , mWinParent(rGraphics)
+{
+}
+
+void WinSkiaSalGraphicsImpl::createWindowContext(bool forceRaster)
+{
+    SkiaZone zone;
+    sk_app::DisplayParams displayParams;
+    switch (forceRaster ? SkiaHelper::RenderRaster : SkiaHelper::renderMethodToUse())
+    {
+        case SkiaHelper::RenderRaster:
+            mWindowContext = sk_app::window_context_factory::MakeRasterForWin(mWinParent.gethWnd(),
+                                                                              displayParams);
+            break;
+        case SkiaHelper::RenderVulkan:
+            mWindowContext = sk_app::window_context_factory::MakeVulkanForWin(mWinParent.gethWnd(),
+                                                                              displayParams);
+            break;
+    }
+}
+
+void WinSkiaSalGraphicsImpl::DeInit()
+{
+    SkiaZone zone;
+    SkiaSalGraphicsImpl::DeInit();
+    mWindowContext.reset();
+}
+
+void WinSkiaSalGraphicsImpl::freeResources() {}
+
+void WinSkiaSalGraphicsImpl::performFlush()
+{
+    SkiaZone zone;
+    flushDrawing();
+    if (mWindowContext)
+        mWindowContext->swapBuffers();
+}
+
+bool WinSkiaSalGraphicsImpl::TryRenderCachedNativeControl(ControlCacheKey const& rControlCacheKey,
+                                                          int nX, int nY)
+{
+    static bool gbCacheEnabled = !getenv("SAL_WITHOUT_WIDGET_CACHE");
+    if (!gbCacheEnabled)
+        return false;
+
+    auto& controlsCache = SkiaControlsCache::get();
+    SkiaControlCacheType::const_iterator iterator = controlsCache.find(rControlCacheKey);
+    if (iterator == controlsCache.end())
+        return false;
+
+    preDraw();
+    SAL_INFO("vcl.skia.trace", "tryrendercachednativecontrol("
+                                   << this << "): "
+                                   << SkIRect::MakeXYWH(nX, nY, iterator->second->width(),
+                                                        iterator->second->height()));
+    mSurface->getCanvas()->drawImage(iterator->second, nX, nY);
+    postDraw();
+    return true;
+}
+
+bool WinSkiaSalGraphicsImpl::RenderAndCacheNativeControl(CompatibleDC& rWhite, CompatibleDC& rBlack,
+                                                         int nX, int nY,
+                                                         ControlCacheKey& aControlCacheKey)
+{
+    assert(dynamic_cast<SkiaCompatibleDC*>(&rWhite));
+    assert(dynamic_cast<SkiaCompatibleDC*>(&rBlack));
+
+    sk_sp<SkImage> image = static_cast<SkiaCompatibleDC&>(rBlack).getAsImageDiff(
+        static_cast<SkiaCompatibleDC&>(rWhite));
+    preDraw();
+    SAL_INFO("vcl.skia.trace",
+             "renderandcachednativecontrol("
+                 << this << "): " << SkIRect::MakeXYWH(nX, nY, image->width(), image->height()));
+    mSurface->getCanvas()->drawImage(image, nX, nY);
+    postDraw();
+
+    if (!aControlCacheKey.canCacheControl())
+        return true;
+    SkiaControlCachePair pair(aControlCacheKey, std::move(image));
+    SkiaControlsCache::get().insert(std::move(pair));
+    return true;
+}
+
+#ifdef SAL_LOG_INFO
+static HRESULT checkResult(HRESULT hr, const char* file, size_t line)
+{
+    if (FAILED(hr))
+    {
+        OUString sLocationString
+            = OUString::createFromAscii(file) + ":" + OUString::number(line) + " ";
+        SAL_DETAIL_LOG_STREAM(SAL_DETAIL_ENABLE_LOG_INFO, ::SAL_DETAIL_LOG_LEVEL_INFO, "vcl.skia",
+                              sLocationString.toUtf8().getStr(),
+                              "HRESULT failed with: 0x" << OUString::number(hr, 16) << ": "
+                                                        << WindowsErrorStringFromHRESULT(hr));
+    }
+    return hr;
+}
+
+#define CHECKHR(funct) checkResult(funct, __FILE__, __LINE__)
+#else
+#define CHECKHR(funct) (funct)
+#endif
+
+sk_sp<SkTypeface> WinSkiaSalGraphicsImpl::createDirectWriteTypeface(const LOGFONTW& logFont)
+{
+    if (!dwriteDone)
+    {
+        if (SUCCEEDED(
+                CHECKHR(DWriteCreateFactory(DWRITE_FACTORY_TYPE_SHARED, __uuidof(IDWriteFactory),
+                                            reinterpret_cast<IUnknown**>(&dwriteFactory)))))
+        {
+            if (SUCCEEDED(CHECKHR(dwriteFactory->GetGdiInterop(&dwriteGdiInterop))))
+                dwriteFontMgr = SkFontMgr_New_DirectWrite(dwriteFactory);
+            else
+                dwriteFactory->Release();
+        }
+        dwriteDone = true;
+    }
+    IDWriteFont* font = nullptr;
+    IDWriteFontFace* fontFace;
+    IDWriteFontFamily* fontFamily;
+    if (FAILED(CHECKHR(dwriteGdiInterop->CreateFontFromLOGFONT(&logFont, &font))))
+        return nullptr;
+    if (FAILED(CHECKHR(font->CreateFontFace(&fontFace))))
+        return nullptr;
+    if (FAILED(CHECKHR(font->GetFontFamily(&fontFamily))))
+        return nullptr;
+    return sk_sp<SkTypeface>(
+        SkCreateTypefaceDirectWrite(dwriteFontMgr, fontFace, font, fontFamily));
+}
+
+bool WinSkiaSalGraphicsImpl::DrawTextLayout(const GenericSalLayout& rLayout)
+{
+    const WinFontInstance& rWinFont = static_cast<const WinFontInstance&>(rLayout.GetFont());
+    float fHScale = rWinFont.getHScale();
+
+    assert(dynamic_cast<const WinFontInstance*>(&rLayout.GetFont()));
+    const WinFontInstance* pWinFont = static_cast<const WinFontInstance*>(&rLayout.GetFont());
+    const HFONT hLayoutFont = pWinFont->GetHFONT();
+    LOGFONTW logFont;
+    if (GetObjectW(hLayoutFont, sizeof(logFont), &logFont) == 0)
+    {
+        assert(false);
+        return false;
+    }
+    sk_sp<SkTypeface> typeface = createDirectWriteTypeface(logFont);
+    GlyphOrientation glyphOrientation = GlyphOrientation::Apply;
+    if (!typeface) // fall back to GDI text rendering
+    {
+        typeface.reset(SkCreateTypefaceFromLOGFONT(logFont));
+        glyphOrientation = GlyphOrientation::Ignore;
+    }
+    // lfHeight actually depends on DPI, so it's not really font height as such,
+    // but for LOGFONT-based typefaces Skia simply sets lfHeight back to this value
+    // directly.
+    double fontHeight = logFont.lfHeight;
+    if (fontHeight < 0)
+        fontHeight = -fontHeight;
+    SkFont font(typeface, fontHeight, fHScale, 0);
+    font.setEdging(getFontEdging());
+    assert(dynamic_cast<SkiaSalGraphicsImpl*>(mWinParent.GetImpl()));
+    SkiaSalGraphicsImpl* impl = static_cast<SkiaSalGraphicsImpl*>(mWinParent.GetImpl());
+    COLORREF color = ::GetTextColor(mWinParent.getHDC());
+    Color salColor(GetRValue(color), GetGValue(color), GetBValue(color));
+    // The font already is set up to have glyphs rotated as needed.
+    impl->drawGenericLayout(rLayout, salColor, font, glyphOrientation);
+    return true;
+}
+
+SkFont::Edging WinSkiaSalGraphicsImpl::getFontEdging()
+{
+    if (fontEdgingDone)
+        return fontEdging;
+    // Skia needs to be explicitly told what kind of antialiasing should be used,
+    // get it from system settings. This does not actually matter for the text
+    // rendering itself, since Skia has been patched to simply use the setting
+    // from the LOGFONT, which gets set by VCL's ImplGetLogFontFromFontSelect()
+    // and that one normally uses DEFAULT_QUALITY, so Windows will select
+    // the appropriate AA setting. But Skia internally chooses the format to which
+    // the glyphs will be rendered based on this setting (subpixel AA requires colors,
+    // others do not).
+    fontEdging = SkFont::Edging::kAlias;
+    SkFontLCDConfig::LCDOrder lcdOrder = SkFontLCDConfig::kNONE_LCDOrder;
+    BOOL set;
+    if (SystemParametersInfo(SPI_GETFONTSMOOTHING, 0, &set, 0) && set)
+    {
+        UINT set2;
+        if (SystemParametersInfo(SPI_GETFONTSMOOTHINGTYPE, 0, &set2, 0)
+            && set2 == FE_FONTSMOOTHINGCLEARTYPE)
+        {
+            fontEdging = SkFont::Edging::kSubpixelAntiAlias;
+            if (SystemParametersInfo(SPI_GETFONTSMOOTHINGORIENTATION, 0, &set2, 0)
+                && set2 == FE_FONTSMOOTHINGORIENTATIONBGR)
+                lcdOrder = SkFontLCDConfig::kBGR_LCDOrder;
+            else
+                lcdOrder = SkFontLCDConfig::kRGB_LCDOrder; // default
+        }
+        else
+            fontEdging = SkFont::Edging::kAntiAlias;
+    }
+    SkFontLCDConfig::SetSubpixelOrder(lcdOrder);
+    // Cache this, it is actually visible a little bit when profiling.
+    fontEdgingDone = true;
+    return fontEdging;
+}
+
+void WinSkiaSalGraphicsImpl::ClearDevFontCache()
+{
+    dwriteFontMgr.reset();
+    dwriteDone = false;
+    fontEdgingDone = false;
+}
+
+SkiaCompatibleDC::SkiaCompatibleDC(SalGraphics& rGraphics, int x, int y, int width, int height)
+    : CompatibleDC(rGraphics, x, y, width, height, false)
+{
+}
+
+std::unique_ptr<CompatibleDC::Texture> SkiaCompatibleDC::getAsMaskTexture() const
+{
+    auto ret = std::make_unique<SkiaCompatibleDC::Texture>();
+    ret->image = getAsMaskImage();
+    return ret;
+}
+
+sk_sp<SkImage> SkiaCompatibleDC::getAsMaskImage() const
+{
+    SkiaZone zone;
+    // mpData is in the BGRA format, with A unused (and set to 0), and RGB are grey,
+    // so convert it to Skia format, then to 8bit and finally use as alpha mask
+    SkBitmap tmpBitmap;
+    if (!tmpBitmap.installPixels(SkImageInfo::Make(maRects.mnSrcWidth, maRects.mnSrcHeight,
+                                                   kBGRA_8888_SkColorType, kOpaque_SkAlphaType),
+                                 mpData, maRects.mnSrcWidth * 4))
+        abort();
+    tmpBitmap.setImmutable();
+    SkBitmap bitmap8;
+    if (!bitmap8.tryAllocPixels(SkImageInfo::Make(maRects.mnSrcWidth, maRects.mnSrcHeight,
+                                                  kGray_8_SkColorType, kOpaque_SkAlphaType)))
+        abort();
+    SkCanvas canvas8(bitmap8);
+    SkPaint paint8;
+    paint8.setBlendMode(SkBlendMode::kSrc); // copy and convert depth
+    // The data we got is upside-down.
+    SkMatrix matrix;
+    matrix.preTranslate(0, maRects.mnSrcHeight);
+    matrix.setConcat(matrix, SkMatrix::Scale(1, -1));
+    canvas8.concat(matrix);
+    canvas8.drawBitmap(tmpBitmap, 0, 0, &paint8);
+    bitmap8.setImmutable();
+    // use the 8bit data as an alpha channel
+    SkBitmap alpha;
+    alpha.setInfo(bitmap8.info().makeColorType(kAlpha_8_SkColorType), bitmap8.rowBytes());
+    alpha.setPixelRef(sk_ref_sp(bitmap8.pixelRef()), bitmap8.pixelRefOrigin().x(),
+                      bitmap8.pixelRefOrigin().y());
+    alpha.setImmutable();
+    return SkiaHelper::createSkImage(alpha);
+}
+
+sk_sp<SkImage> SkiaCompatibleDC::getAsImage() const
+{
+    SkiaZone zone;
+    SkBitmap tmpBitmap;
+    if (!tmpBitmap.installPixels(SkImageInfo::Make(maRects.mnSrcWidth, maRects.mnSrcHeight,
+                                                   kBGRA_8888_SkColorType, kUnpremul_SkAlphaType),
+                                 mpData, maRects.mnSrcWidth * 4))
+        abort();
+    tmpBitmap.setImmutable();
+    sk_sp<SkSurface> surface = SkiaHelper::createSkSurface(tmpBitmap.width(), tmpBitmap.height());
+    SkPaint paint;
+    paint.setBlendMode(SkBlendMode::kSrc); // set as is, including alpha
+    SkCanvas* canvas = surface->getCanvas();
+    canvas->save();
+    // The data we got is upside-down.
+    SkMatrix matrix;
+    matrix.preTranslate(0, maRects.mnSrcHeight);
+    matrix.setConcat(matrix, SkMatrix::Scale(1, -1));
+    canvas->concat(matrix);
+    canvas->drawBitmapRect(tmpBitmap,
+                           SkRect::MakeXYWH(0, 0, maRects.mnSrcWidth, maRects.mnSrcHeight),
+                           SkRect::MakeXYWH(0, 0, maRects.mnSrcWidth, maRects.mnSrcHeight), &paint);
+    canvas->restore();
+    return SkiaHelper::makeCheckedImageSnapshot(surface);
+}
+
+sk_sp<SkImage> SkiaCompatibleDC::getAsImageDiff(const SkiaCompatibleDC& white) const
+{
+    SkiaZone zone;
+    assert(maRects.mnSrcWidth == white.maRects.mnSrcWidth
+           || maRects.mnSrcHeight == white.maRects.mnSrcHeight);
+    SkBitmap tmpBitmap;
+    if (!tmpBitmap.tryAllocPixels(SkImageInfo::Make(maRects.mnSrcWidth, maRects.mnSrcHeight,
+                                                    kBGRA_8888_SkColorType, kPremul_SkAlphaType),
+                                  maRects.mnSrcWidth * 4))
+        abort();
+    // Native widgets are drawn twice on black/white background to synthetize alpha
+    // (commit c6b66646870cb2bffaa73565affcf80bf74e0b5c). The problem is that
+    // most widgets when drawn on transparent background are drawn properly (and the result
+    // is in premultiplied alpha format), some such as "Edit" (used by ControlType::Editbox)
+    // keep the alpha channel as transparent. Therefore the alpha is actually computed
+    // from the difference in the premultiplied red channels when drawn one black and on white.
+    // Alpha is computed as "alpha = 1.0 - abs(black.red - white.red)".
+    // TODO I doubt this can be done using Skia, so do it manually here. Fortunately
+    // the bitmaps should be fairly small and are cached.
+    uint32_t* dest = tmpBitmap.getAddr32(0, 0);
+    assert(dest == tmpBitmap.getPixels());
+    const sal_uInt32* src = mpData;
+    const sal_uInt32* whiteSrc = white.mpData;
+    uint32_t* end = dest + tmpBitmap.width() * tmpBitmap.height();
+    while (dest < end)
+    {
+        uint32_t alpha = 255 - abs(int(*src & 0xff) - int(*whiteSrc & 0xff));
+        *dest = (*src & 0x00ffffff) | (alpha << 24);
+        ++dest;
+        ++src;
+        ++whiteSrc;
+    }
+    tmpBitmap.notifyPixelsChanged();
+    tmpBitmap.setImmutable();
+    sk_sp<SkSurface> surface = SkiaHelper::createSkSurface(tmpBitmap.width(), tmpBitmap.height());
+    SkPaint paint;
+    paint.setBlendMode(SkBlendMode::kSrc); // set as is, including alpha
+    SkCanvas* canvas = surface->getCanvas();
+    canvas->save();
+    // The data we got is upside-down.
+    SkMatrix matrix;
+    matrix.preTranslate(0, tmpBitmap.height());
+    matrix.setConcat(matrix, SkMatrix::Scale(1, -1));
+    canvas->concat(matrix);
+    canvas->drawBitmap(tmpBitmap, 0, 0, &paint);
+    canvas->restore();
+    return SkiaHelper::makeCheckedImageSnapshot(surface);
+}
+
+SkiaControlsCache::SkiaControlsCache()
+    : cache(200)
+{
+}
+
+SkiaControlCacheType& SkiaControlsCache::get()
+{
+    SalData* data = GetSalData();
+    if (!data->m_pSkiaControlsCache)
+        data->m_pSkiaControlsCache.reset(new SkiaControlsCache);
+    return data->m_pSkiaControlsCache->cache;
+}
+
+namespace
+{
+std::unique_ptr<sk_app::WindowContext> createVulkanWindowContext(bool /*temporary*/)
+{
+    SkiaZone zone;
+    sk_app::DisplayParams displayParams;
+    return sk_app::window_context_factory::MakeVulkanForWin(nullptr, displayParams);
+}
+}
+
+void WinSkiaSalGraphicsImpl::prepareSkia() { SkiaHelper::prepareSkia(createVulkanWindowContext); }
+
+/* vim:set shiftwidth=4 softtabstop=4 expandtab: */
diff --git a/vcl/skia/x11/gdiimpl.cxx b/vcl/skia/x11/gdiimpl.cxx
new file mode 100644
index 000000000..1602218c1
--- /dev/null
+++ b/vcl/skia/x11/gdiimpl.cxx
@@ -0,0 +1,161 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/*
+ * This file is part of the LibreOffice project.
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ *
+ * Some of this code is based on Skia source code, covered by the following
+ * license notice (see readlicense_oo for the full license):
+ *
+ * Copyright 2016 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ *
+ */
+
+#include <skia/x11/gdiimpl.hxx>
+
+#include <tools/sk_app/unix/WindowContextFactory_unix.h>
+
+#include <skia/utils.hxx>
+#include <skia/zone.hxx>
+
+#include <X11/Xutil.h>
+
+X11SkiaSalGraphicsImpl::X11SkiaSalGraphicsImpl(X11SalGraphics& rParent)
+    : SkiaSalGraphicsImpl(rParent, rParent.GetGeometryProvider())
+    , mX11Parent(rParent)
+{
+}
+
+X11SkiaSalGraphicsImpl::~X11SkiaSalGraphicsImpl() {}
+
+void X11SkiaSalGraphicsImpl::Init()
+{
+    // The m_pFrame and m_pVDev pointers are updated late in X11
+    setProvider(mX11Parent.GetGeometryProvider());
+    SkiaSalGraphicsImpl::Init();
+}
+
+void X11SkiaSalGraphicsImpl::createWindowContext(bool forceRaster)
+{
+    assert(mX11Parent.GetDrawable() != None);
+    mWindowContext = createWindowContext(
+        mX11Parent.GetXDisplay(), mX11Parent.GetDrawable(), &mX11Parent.GetVisual(), GetWidth(),
+        GetHeight(), forceRaster ? SkiaHelper::RenderRaster : SkiaHelper::renderMethodToUse(),
+        false);
+}
+
+std::unique_ptr<sk_app::WindowContext>
+X11SkiaSalGraphicsImpl::createWindowContext(Display* display, Drawable drawable,
+                                            const XVisualInfo* visual, int width, int height,
+                                            SkiaHelper::RenderMethod renderMethod, bool temporary)
+{
+    SkiaZone zone;
+    sk_app::DisplayParams displayParams;
+    displayParams.fColorType = kN32_SkColorType;
+    sk_app::window_context_factory::XlibWindowInfo winInfo;
+    assert(display);
+    winInfo.fDisplay = display;
+    winInfo.fWindow = drawable;
+    winInfo.fFBConfig = nullptr; // not used
+    winInfo.fVisualInfo = const_cast<XVisualInfo*>(visual);
+    assert(winInfo.fVisualInfo->visual != nullptr); // make sure it's not an uninitialized SalVisual
+    winInfo.fWidth = width;
+    winInfo.fHeight = height;
+#ifdef DBG_UTIL
+    // Our patched Skia has VulkanWindowContext that shares GrContext, which requires
+    // that the X11 visual is always the same. Ensure it is so.
+    static VisualID checkVisualID = -1U;
+    // Exception is for the temporary case during startup, when SkiaHelper's
+    // checkDeviceBlacklisted() needs a WindowContext and may be called before SalVisual
+    // is ready.
+    if (!temporary)
+    {
+        assert(checkVisualID == -1U || winInfo.fVisualInfo->visualid == checkVisualID);
+        checkVisualID = winInfo.fVisualInfo->visualid;
+    }
+#else
+    (void)temporary;
+#endif
+    switch (renderMethod)
+    {
+        case SkiaHelper::RenderRaster:
+            // TODO The Skia Xlib code actually requires the non-native color type to work properly.
+            displayParams.fColorType
+                = (displayParams.fColorType == kBGRA_8888_SkColorType ? kRGBA_8888_SkColorType
+                                                                      : kBGRA_8888_SkColorType);
+            return sk_app::window_context_factory::MakeRasterForXlib(winInfo, displayParams);
+        case SkiaHelper::RenderVulkan:
+            return sk_app::window_context_factory::MakeVulkanForXlib(winInfo, displayParams);
+    }
+    abort();
+}
+
+bool X11SkiaSalGraphicsImpl::avoidRecreateByResize() const
+{
+    if (!mSurface || isOffscreen())
+        return false;
+    // Skia's WindowContext uses actual dimensions of the X window, which due to X11 being
+    // asynchronous may be temporarily different from what VCL thinks are the dimensions.
+    // That can lead to us repeatedly calling recreateSurface() because of "incorrect"
+    // size, and we otherwise need to check for size changes, because VCL does not inform us.
+    // Avoid the problem here by checking the size of the X window and bail out if Skia
+    // would just return the same size as it is now.
+    Window r;
+    int x, y;
+    unsigned int w, h, border, depth;
+    XGetGeometry(mX11Parent.GetXDisplay(), mX11Parent.GetDrawable(), &r, &x, &y, &w, &h, &border,
+                 &depth);
+    return mSurface->width() == int(w) && mSurface->height() == int(h);
+}
+
+void X11SkiaSalGraphicsImpl::DeInit()
+{
+    SkiaZone zone;
+    SkiaSalGraphicsImpl::DeInit();
+    mWindowContext.reset();
+}
+
+void X11SkiaSalGraphicsImpl::freeResources() {}
+
+void X11SkiaSalGraphicsImpl::performFlush()
+{
+    SkiaZone zone;
+    flushDrawing();
+    // TODO XPutImage() is somewhat inefficient, XShmPutImage() should be preferred.
+    mWindowContext->swapBuffers();
+}
+
+std::unique_ptr<sk_app::WindowContext> createVulkanWindowContext(bool temporary)
+{
+    SalDisplay* salDisplay = vcl_sal::getSalDisplay(GetGenericUnixSalData());
+    const XVisualInfo* visual;
+    XVisualInfo* visuals = nullptr;
+    if (!temporary)
+        visual = &salDisplay->GetVisual(salDisplay->GetDefaultXScreen());
+    else
+    {
+        // SalVisual from salDisplay may not be setup yet at this point, get
+        // info for the default visual.
+        XVisualInfo search;
+        search.visualid = XVisualIDFromVisual(
+            DefaultVisual(salDisplay->GetDisplay(), salDisplay->GetDefaultXScreen().getXScreen()));
+        int count;
+        visuals = XGetVisualInfo(salDisplay->GetDisplay(), VisualIDMask, &search, &count);
+        assert(count == 1);
+        visual = visuals;
+    }
+    std::unique_ptr<sk_app::WindowContext> ret = X11SkiaSalGraphicsImpl::createWindowContext(
+        salDisplay->GetDisplay(), None, visual, 1, 1, SkiaHelper::RenderVulkan, temporary);
+    if (temporary)
+        XFree(visuals);
+    return ret;
+}
+
+void X11SkiaSalGraphicsImpl::prepareSkia() { SkiaHelper::prepareSkia(createVulkanWindowContext); }
+
+/* vim:set shiftwidth=4 softtabstop=4 expandtab: */
diff --git a/vcl/skia/x11/salvd.cxx b/vcl/skia/x11/salvd.cxx
new file mode 100644
index 000000000..a4db9c75d
--- /dev/null
+++ b/vcl/skia/x11/salvd.cxx
@@ -0,0 +1,86 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/*
+ * This file is part of the LibreOffice project.
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ */
+
+#include <vcl/sysdata.hxx>
+
+#include <unx/salunx.h>
+#include <unx/saldisp.hxx>
+#include <unx/salgdi.h>
+#include <unx/salvd.h>
+
+#include <skia/x11/salvd.hxx>
+
+void X11SalGraphics::Init(X11SkiaSalVirtualDevice* pDevice)
+{
+    SalDisplay* pDisplay = pDevice->GetDisplay();
+
+    m_nXScreen = pDevice->GetXScreenNumber();
+    m_pColormap = &pDisplay->GetColormap(m_nXScreen);
+
+    m_pVDev = pDevice;
+    m_pFrame = nullptr;
+
+    bWindow_ = pDisplay->IsDisplay();
+    bVirDev_ = true;
+
+    mxImpl->Init();
+}
+
+X11SkiaSalVirtualDevice::X11SkiaSalVirtualDevice(SalGraphics const* pGraphics, long nDX, long nDY,
+                                                 const SystemGraphicsData* pData,
+                                                 std::unique_ptr<X11SalGraphics> pNewGraphics)
+    : mpGraphics(std::move(pNewGraphics))
+    , mbGraphics(false)
+    , mnXScreen(0)
+{
+    assert(mpGraphics);
+
+    // TODO Check where a VirtualDevice is created from SystemGraphicsData
+    assert(pData == nullptr);
+    (void)pData;
+
+    mpDisplay = vcl_sal::getSalDisplay(GetGenericUnixSalData());
+    mnXScreen = pGraphics ? static_cast<X11SalGraphics const*>(pGraphics)->GetScreenNumber()
+                          : vcl_sal::getSalDisplay(GetGenericUnixSalData())->GetDefaultXScreen();
+    mnWidth = nDX;
+    mnHeight = nDY;
+    mpGraphics->Init(this);
+}
+
+X11SkiaSalVirtualDevice::~X11SkiaSalVirtualDevice() {}
+
+SalGraphics* X11SkiaSalVirtualDevice::AcquireGraphics()
+{
+    if (mbGraphics)
+        return nullptr;
+
+    if (mpGraphics)
+        mbGraphics = true;
+
+    return mpGraphics.get();
+}
+
+void X11SkiaSalVirtualDevice::ReleaseGraphics(SalGraphics*) { mbGraphics = false; }
+
+bool X11SkiaSalVirtualDevice::SetSize(long nDX, long nDY)
+{
+    if (!nDX)
+        nDX = 1;
+    if (!nDY)
+        nDY = 1;
+
+    mnWidth = nDX;
+    mnHeight = nDY;
+    if (mpGraphics)
+        mpGraphics->Init(this);
+
+    return true;
+}
+
+/* vim:set shiftwidth=4 softtabstop=4 expandtab: */
diff --git a/vcl/skia/x11/textrender.cxx b/vcl/skia/x11/textrender.cxx
new file mode 100644
index 000000000..13eff3012
--- /dev/null
+++ b/vcl/skia/x11/textrender.cxx
@@ -0,0 +1,80 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/*
+ * This file is part of the LibreOffice project.
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ *
+ * This file incorporates work covered by the following license notice:
+ *
+ *   Licensed to the Apache Software Foundation (ASF) under one or more
+ *   contributor license agreements. See the NOTICE file distributed
+ *   with this work for additional information regarding copyright
+ *   ownership. The ASF licenses this file to you under the Apache
+ *   License, Version 2.0 (the "License"); you may not use this file
+ *   except in compliance with the License. You may obtain a copy of
+ *   the License at http://www.apache.org/licenses/LICENSE-2.0 .
+ */
+
+#include <skia/x11/textrender.hxx>
+
+#include <unx/fc_fontoptions.hxx>
+#include <unx/freetype_glyphcache.hxx>
+#include <vcl/svapp.hxx>
+#include <sallayout.hxx>
+#include <skia/gdiimpl.hxx>
+
+#include <SkFont.h>
+#include <SkFontMgr_fontconfig.h>
+
+void SkiaTextRender::DrawTextLayout(const GenericSalLayout& rLayout, const SalGraphics& rGraphics)
+{
+    const FreetypeFontInstance& rInstance = static_cast<FreetypeFontInstance&>(rLayout.GetFont());
+    const FreetypeFont& rFont = rInstance.GetFreetypeFont();
+    const FontSelectPattern& rFSD = rInstance.GetFontSelectPattern();
+    int nHeight = rFSD.mnHeight;
+    int nWidth = rFSD.mnWidth ? rFSD.mnWidth : nHeight;
+    if (nWidth == 0 || nHeight == 0)
+        return;
+
+    if (FreetypeFont::AlmostHorizontalDrainsRenderingPool(nWidth * 10 / nHeight, rFSD))
+        return;
+
+    if (!fontManager)
+    {
+        // Get the global FcConfig that our VCL fontconfig code uses, and refcount it.
+        fontManager = SkFontMgr_New_FontConfig(FcConfigReference(nullptr));
+    }
+    sk_sp<SkTypeface> typeface
+        = SkFontMgr_createTypefaceFromFcPattern(fontManager, rFont.GetFontOptions()->GetPattern());
+    SkFont font(typeface, nHeight);
+    // TODO are these correct?
+    if (rFont.NeedsArtificialItalic())
+        font.setSkewX(-0x6000L / 0x10000L);
+    if (rFont.NeedsArtificialBold())
+        font.setEmbolden(true);
+    font.setEdging(rFont.GetAntialiasAdvice() ? SkFont::Edging::kAntiAlias
+                                              : SkFont::Edging::kAlias);
+
+    assert(dynamic_cast<SkiaSalGraphicsImpl*>(rGraphics.GetImpl()));
+    SkiaSalGraphicsImpl* impl = static_cast<SkiaSalGraphicsImpl*>(rGraphics.GetImpl());
+    impl->drawGenericLayout(rLayout, mnTextColor, font,
+                            SkiaSalGraphicsImpl::GlyphOrientation::Apply);
+}
+
+void SkiaTextRender::ClearDevFontCache() { fontManager.reset(); }
+
+#if 0
+// SKIA TODO
+void FontConfigFontOptions::cairo_font_options_substitute(FcPattern* pPattern)
+{
+    ImplSVData* pSVData = ImplGetSVData();
+    const cairo_font_options_t* pFontOptions = pSVData->mpDefInst->GetCairoFontOptions();
+    if( !pFontOptions )
+        return;
+    cairo_ft_font_options_substitute(pFontOptions, pPattern);
+}
+#endif
+
+/* vim:set shiftwidth=4 softtabstop=4 expandtab: */
diff --git a/vcl/skia/zone.cxx b/vcl/skia/zone.cxx
new file mode 100644
index 000000000..50f5e1ea7
--- /dev/null
+++ b/vcl/skia/zone.cxx
@@ -0,0 +1,76 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/*
+ * This file is part of the LibreOffice project.
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ */
+
+#include <skia/zone.hxx>
+
+#include <officecfg/Office/Common.hxx>
+#include <com/sun/star/util/XFlushable.hpp>
+#include <com/sun/star/configuration/theDefaultProvider.hpp>
+
+#include <sal/log.hxx>
+#include <o3tl/unreachable.hxx>
+
+#include <vcl/skia/SkiaHelper.hxx>
+
+/**
+ * Called from a signal handler or watchdog thread if we get
+ * a crash or hang in some driver.
+ */
+void SkiaZone::hardDisable()
+{
+    // protect ourselves from double calling etc.
+    static bool bDisabled = false;
+    if (!bDisabled)
+    {
+        bDisabled = true;
+
+        // Instead of disabling Skia as a whole, only force the CPU-based
+        // raster mode, which should be safe as it does not use drivers.
+        std::shared_ptr<comphelper::ConfigurationChanges> xChanges(
+            comphelper::ConfigurationChanges::create());
+        officecfg::Office::Common::VCL::ForceSkiaRaster::set(true, xChanges);
+        xChanges->commit();
+
+        // Force synchronous config write
+        css::uno::Reference<css::util::XFlushable>(
+            css::configuration::theDefaultProvider::get(comphelper::getProcessComponentContext()),
+            css::uno::UNO_QUERY_THROW)
+            ->flush();
+    }
+}
+
+void SkiaZone::checkDebug(int nUnchanged, const CrashWatchdogTimingsValues& aTimingValues)
+{
+    SAL_INFO("vcl.watchdog", "Skia watchdog - unchanged "
+                                 << nUnchanged << " enter count " << enterCount()
+                                 << " breakpoints mid: " << aTimingValues.mnDisableEntries
+                                 << " max " << aTimingValues.mnAbortAfter);
+}
+
+const CrashWatchdogTimingsValues& SkiaZone::getCrashWatchdogTimingsValues()
+{
+    switch (SkiaHelper::renderMethodToUse())
+    {
+        case SkiaHelper::RenderVulkan:
+        {
+            static const CrashWatchdogTimingsValues vulkanValues = { 6, 20 }; /* 1.5s,  5s */
+            return vulkanValues;
+        }
+        case SkiaHelper::RenderRaster:
+        {
+            // CPU-based operations with large images may take a noticeably long time,
+            // so use large values. CPU-based rendering shouldn't use any unstable drivers anyway.
+            static const CrashWatchdogTimingsValues rasterValues = { 600, 2000 }; /* 150s,  500s */
+            return rasterValues;
+        }
+    }
+    O3TL_UNREACHABLE;
+}
+
+/* vim:set shiftwidth=4 softtabstop=4 expandtab: */