Adding upstream version 4:7.4.7.upstream/4%7.4.7upstream

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

1 files changed, 1406 insertions, 0 deletions

diff --git a/vcl/skia/salbmp.cxx b/vcl/skia/salbmp.cxx
new file mode 100644
index 000000000..df3536b4d
--- /dev/null
+++ b/vcl/skia/salbmp.cxx
@@ -0,0 +1,1406 @@
+/* -*- 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 <bitmap/bmpfast.hxx>
+#include <vcl/BitmapReadAccess.hxx>
+
+#include <skia/utils.hxx>
+#include <skia/zone.hxx>
+
+#include <SkCanvas.h>
+#include <SkImage.h>
+#include <SkPixelRef.h>
+#include <SkSurface.h>
+#include <SkSwizzle.h>
+#include <SkColorFilter.h>
+#include <SkColorMatrix.h>
+#include <skia_opts.hxx>
+
+#ifdef DBG_UTIL
+#include <fstream>
+#define CANARY "skia-canary"
+#endif
+
+using namespace SkiaHelper;
+
+// As constexpr here, evaluating it directly in code makes Clang warn about unreachable code.
+constexpr bool kN32_SkColorTypeIsBGRA = (kN32_SkColorType == kBGRA_8888_SkColorType);
+
+SkiaSalBitmap::SkiaSalBitmap() {}
+
+SkiaSalBitmap::~SkiaSalBitmap() {}
+
+SkiaSalBitmap::SkiaSalBitmap(const sk_sp<SkImage>& image)
+{
+    ResetAllData();
+    mImage = image;
+    mPalette = BitmapPalette();
+#if SKIA_USE_BITMAP32
+    mBitCount = 32;
+#else
+    mBitCount = 24;
+#endif
+    mSize = mPixelsSize = Size(image->width(), image->height());
+    ComputeScanlineSize();
+    mAnyAccessCount = 0;
+#ifdef DBG_UTIL
+    mWriteAccessCount = 0;
+#endif
+    SAL_INFO("vcl.skia.trace", "bitmapfromimage(" << this << ")");
+}
+
+bool SkiaSalBitmap::Create(const Size& rSize, vcl::PixelFormat ePixelFormat,
+                           const BitmapPalette& rPal)
+{
+    assert(mAnyAccessCount == 0);
+    ResetAllData();
+    if (ePixelFormat == vcl::PixelFormat::INVALID)
+        return false;
+    mPalette = rPal;
+    mBitCount = vcl::pixelFormatBitCount(ePixelFormat);
+    mSize = rSize;
+    ResetPendingScaling();
+    if (!ComputeScanlineSize())
+    {
+        mBitCount = 0;
+        mSize = mPixelsSize = Size();
+        mScanlineSize = 0;
+        mPalette = BitmapPalette();
+        return false;
+    }
+    SAL_INFO("vcl.skia.trace", "create(" << this << ")");
+    return true;
+}
+
+bool SkiaSalBitmap::ComputeScanlineSize()
+{
+    int bitScanlineWidth;
+    if (o3tl::checked_multiply<int>(mPixelsSize.Width(), mBitCount, bitScanlineWidth))
+    {
+        SAL_WARN("vcl.skia", "checked multiply failed");
+        return false;
+    }
+    mScanlineSize = AlignedWidth4Bytes(bitScanlineWidth);
+    return true;
+}
+
+void SkiaSalBitmap::CreateBitmapData()
+{
+    assert(!mBuffer);
+    // Make sure code has not missed calling ComputeScanlineSize().
+    assert(mScanlineSize == int(AlignedWidth4Bytes(mPixelsSize.Width() * mBitCount)));
+    // 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.
+    if (mScanlineSize == 0 || mPixelsSize.Height() == 0)
+        return;
+
+    size_t allocate = mScanlineSize * mPixelsSize.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
+}
+
+bool SkiaSalBitmap::Create(const SalBitmap& rSalBmp)
+{
+    return Create(rSalBmp, vcl::bitDepthToPixelFormat(rSalBmp.GetBitCount()));
+}
+
+bool SkiaSalBitmap::Create(const SalBitmap& rSalBmp, SalGraphics* pGraphics)
+{
+    auto ePixelFormat = vcl::PixelFormat::INVALID;
+    if (pGraphics)
+        ePixelFormat = vcl::bitDepthToPixelFormat(pGraphics->GetBitCount());
+    else
+        ePixelFormat = vcl::bitDepthToPixelFormat(rSalBmp.GetBitCount());
+
+    return Create(rSalBmp, ePixelFormat);
+}
+
+bool SkiaSalBitmap::Create(const SalBitmap& rSalBmp, vcl::PixelFormat eNewPixelFormat)
+{
+    assert(mAnyAccessCount == 0);
+    assert(&rSalBmp != this);
+    ResetAllData();
+    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;
+    mEraseColorSet = src.mEraseColorSet;
+    mEraseColor = src.mEraseColor;
+    if (vcl::pixelFormatBitCount(eNewPixelFormat) != 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)
+{
+    return false;
+}
+
+void SkiaSalBitmap::Destroy()
+{
+    SAL_INFO("vcl.skia.trace", "destroy(" << this << ")");
+#ifdef DBG_UTIL
+    assert(mWriteAccessCount == 0);
+#endif
+    assert(mAnyAccessCount == 0);
+    ResetAllData();
+}
+
+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;
+            assert(mPixelsSize == mSize);
+            assert(!mEraseColorSet);
+            break;
+        case BitmapAccessMode::Read:
+            EnsureBitmapData();
+            if (!mBuffer)
+                return nullptr;
+            assert(mPixelsSize == mSize);
+            assert(!mEraseColorSet);
+            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;
+    if (nMode != BitmapAccessMode::Info)
+        buffer->mpBits = mBuffer.get();
+    else
+        buffer->mpBits = nullptr;
+    if (mPixelsSize == mSize)
+        buffer->mnScanlineSize = mScanlineSize;
+    else
+    {
+        // The value of mScanlineSize is based on internal mPixelsSize, but the outside
+        // world cares about mSize, the size that the report as the size of the bitmap,
+        // regardless of any internal state. So report scanline size for that size.
+        Size savedPixelsSize = mPixelsSize;
+        mPixelsSize = mSize;
+        ComputeScanlineSize();
+        buffer->mnScanlineSize = mScanlineSize;
+        mPixelsSize = savedPixelsSize;
+        ComputeScanlineSize();
+    }
+    switch (mBitCount)
+    {
+        case 1:
+            buffer->mnFormat = ScanlineFormat::N1BitMsbPal;
+            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.
+            buffer->mnFormat = kN32_SkColorTypeIsBGRA ? ScanlineFormat::N24BitTcBgr
+                                                      : ScanlineFormat::N24BitTcRgb;
+            break;
+        case 32:
+            buffer->mnFormat = kN32_SkColorTypeIsBGRA ? ScanlineFormat::N32BitTcBgra
+                                                      : ScanlineFormat::N32BitTcRgba;
+            break;
+        default:
+            abort();
+    }
+    buffer->mnFormat |= ScanlineFormat::TopDown;
+    ++mAnyAccessCount;
+#ifdef DBG_UTIL
+    if (nMode == BitmapAccessMode::Write)
+        ++mWriteAccessCount;
+#endif
+    return buffer;
+}
+
+void SkiaSalBitmap::ReleaseBuffer(BitmapBuffer* pBuffer, BitmapAccessMode nMode)
+{
+    ReleaseBuffer(pBuffer, nMode, false);
+}
+
+void SkiaSalBitmap::ReleaseBuffer(BitmapBuffer* pBuffer, BitmapAccessMode nMode,
+                                  bool dontChangeToErase)
+{
+    if (nMode == BitmapAccessMode::Write)
+    {
+#ifdef DBG_UTIL
+        assert(mWriteAccessCount > 0);
+        --mWriteAccessCount;
+#endif
+        mPalette = pBuffer->maPalette;
+        ResetToBuffer();
+        DataChanged();
+    }
+    assert(mAnyAccessCount > 0);
+    --mAnyAccessCount;
+    // Are there any more ground movements underneath us ?
+    assert(pBuffer->mnWidth == mSize.Width());
+    assert(pBuffer->mnHeight == mSize.Height());
+    assert(pBuffer->mnBitCount == mBitCount);
+    assert(pBuffer->mpBits == mBuffer.get() || nMode == BitmapAccessMode::Info);
+    verify();
+    delete pBuffer;
+    if (nMode == BitmapAccessMode::Write && !dontChangeToErase)
+    {
+        // This saves memory and is also used by IsFullyOpaqueAsAlpha() to avoid unnecessary
+        // alpha blending.
+        if (IsAllBlack())
+        {
+            SAL_INFO("vcl.skia.trace", "releasebuffer(" << this << "): erasing to black");
+            EraseInternal(COL_BLACK);
+        }
+    }
+}
+
+static bool isAllZero(const sal_uInt8* data, size_t size)
+{ // For performance, check in larger data chunks.
+#ifdef UINT64_MAX
+    const int64_t* d = reinterpret_cast<const int64_t*>(data);
+#else
+    const int32_t* d = reinterpret_cast<const int32_t*>(data);
+#endif
+    constexpr size_t step = sizeof(*d) * 8;
+    for (size_t i = 0; i < size / step; ++i)
+    { // Unrolled loop.
+        if (d[0] != 0)
+            return false;
+        if (d[1] != 0)
+            return false;
+        if (d[2] != 0)
+            return false;
+        if (d[3] != 0)
+            return false;
+        if (d[4] != 0)
+            return false;
+        if (d[5] != 0)
+            return false;
+        if (d[6] != 0)
+            return false;
+        if (d[7] != 0)
+            return false;
+        d += 8;
+    }
+    for (size_t i = size / step * step; i < size; ++i)
+        if (data[i] != 0)
+            return false;
+    return true;
+}
+
+bool SkiaSalBitmap::IsAllBlack() const
+{
+    if (mBitCount % 8 != 0 || (!!mPalette && mPalette[0] != COL_BLACK))
+        return false; // Don't bother.
+    if (mSize.Width() * mBitCount / 8 == mScanlineSize)
+        return isAllZero(mBuffer.get(), mScanlineSize * mSize.Height());
+    for (tools::Long y = 0; y < mSize.Height(); ++y)
+        if (!isAllZero(mBuffer.get() + mScanlineSize * y, mSize.Width() * mBitCount / 8))
+            return false;
+    return true;
+}
+
+bool SkiaSalBitmap::GetSystemData(BitmapSystemData&)
+{
+#ifdef DBG_UTIL
+    assert(mWriteAccessCount == 0);
+#endif
+    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));
+
+    if (mEraseColorSet)
+    { // Simple.
+        mSize = newSize;
+        ResetPendingScaling();
+        EraseInternal(mEraseColor);
+        return true;
+    }
+
+    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;
+    }
+    // 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' for mBuffer,
+    // and 'imageSize(mImage) != mSize' for mImage. It is not intended to have 3 different
+    // sizes though, code below keeps only mBuffer or mImage. Note that imageSize(mImage)
+    // may or may not be equal to mPixelsSize, depending on whether mImage is set here
+    // (sizes will be equal) or whether it's set in GetSkImage() (will not be equal).
+    // Pending scaling is considered "done" by the time mBuffer is resized (or created).
+    // Resizing of mImage is somewhat independent of this, since mImage is primarily
+    // considered to be a cached object (although sometimes it's the only data available).
+
+    // If there is already one scale() pending, use the lowest quality of all requested.
+    switch (nScaleFlag)
+    {
+        case BmpScaleFlag::Fast:
+            mScaleQuality = nScaleFlag;
+            break;
+        case BmpScaleFlag::NearestNeighbor:
+            // We handle this the same way as Fast by mapping to Skia's nearest-neighbor,
+            // and it's needed for unittests (mScaling and testTdf132367()).
+            mScaleQuality = nScaleFlag;
+            break;
+        case BmpScaleFlag::Default:
+            if (mScaleQuality == BmpScaleFlag::BestQuality)
+                mScaleQuality = nScaleFlag;
+            break;
+        case BmpScaleFlag::BestQuality:
+            // Best is the maximum, set by default.
+            break;
+        default:
+            SAL_INFO("vcl.skia.trace", "scale(" << this << "): unsupported scale algorithm");
+            return false;
+    }
+    mSize = newSize;
+    // If we have both mBuffer and mImage, prefer mImage, since it likely will be drawn later.
+    // We could possibly try to keep the buffer as well, but that would complicate things
+    // with two different data structures to be scaled on-demand, and it's a question
+    // if that'd realistically help with anything.
+    if (mImage)
+        ResetToSkImage(mImage);
+    else
+        ResetToBuffer();
+    DataChanged();
+    // 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
+    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 && !mEraseColorSet)
+    {
+        if (mBitCount == 8 && mPalette.IsGreyPalette8Bit())
+            return true;
+        sk_sp<SkSurface> surface
+            = createSkSurface(imageSize(mImage), mImage->imageInfo().alphaType());
+        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, SkSamplingOptions(), &paint);
+        mBitCount = 8;
+        ComputeScanlineSize();
+        mPalette = Bitmap::GetGreyPalette(256);
+        ResetToSkImage(makeCheckedImageSnapshot(surface));
+        DataChanged();
+        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;
+    if (mEraseColorSet)
+    {
+        mBitCount = 8;
+        ComputeScanlineSize();
+        mPalette = Bitmap::GetGreyPalette(256);
+        EraseInternal(mEraseColor);
+        SAL_INFO("vcl.skia.trace", "interpretas8bit(" << this << ") with erase color");
+        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 (mImage)
+    {
+        mBitCount = 8;
+        ComputeScanlineSize();
+        mPalette = Bitmap::GetGreyPalette(256);
+        ResetToSkImage(mImage); // keep mImage, it will be interpreted as 8bit if needed
+        DataChanged();
+        SAL_INFO("vcl.skia.trace", "interpretas8bit(" << this << ") with image");
+        return true;
+    }
+    SAL_INFO("vcl.skia.trace", "interpretas8bit(" << this << ") with pixel data, ignoring");
+    return false;
+}
+
+bool SkiaSalBitmap::Erase(const Color& color)
+{
+#ifdef DBG_UTIL
+    assert(mWriteAccessCount == 0);
+#endif
+    // Optimized variant, just remember the color and apply it when needed,
+    // which may save having to do format conversions (e.g. GetSkImage()
+    // may directly erase the SkImage).
+    EraseInternal(color);
+    SAL_INFO("vcl.skia.trace", "erase(" << this << ")");
+    return true;
+}
+
+void SkiaSalBitmap::EraseInternal(const Color& color)
+{
+    ResetAllData();
+    mEraseColorSet = true;
+    mEraseColor = color;
+}
+
+bool SkiaSalBitmap::AlphaBlendWith(const SalBitmap& rSalBmp)
+{
+#ifdef DBG_UTIL
+    assert(mWriteAccessCount == 0);
+#endif
+    const SkiaSalBitmap* otherBitmap = dynamic_cast<const SkiaSalBitmap*>(&rSalBmp);
+    if (!otherBitmap)
+        return false;
+    if (mSize != otherBitmap->mSize)
+        return false;
+    // We're called from AlphaMask, which should ensure 8bit.
+    assert(GetBitCount() == 8 && mPalette.IsGreyPalette8Bit());
+    // If neither bitmap have Skia images, then AlphaMask::BlendWith() will be faster,
+    // as it will operate on mBuffer pixel buffers, while for Skia we'd need to convert it.
+    // If one has and one doesn't, do it using Skia, under the assumption that after this
+    // the resulting Skia image will be needed for drawing.
+    if (!(mImage || mEraseColorSet) && !(otherBitmap->mImage || otherBitmap->mEraseColorSet))
+        return false;
+    // This is for AlphaMask, which actually stores the alpha as the pixel values.
+    // I.e. take value of the color channel (one of them, if >8bit, they should be the same).
+    if (mEraseColorSet && otherBitmap->mEraseColorSet)
+    {
+        const sal_uInt16 nGrey1 = mEraseColor.GetRed();
+        const sal_uInt16 nGrey2 = otherBitmap->mEraseColor.GetRed();
+        const sal_uInt8 nGrey = static_cast<sal_uInt8>(nGrey1 + nGrey2 - nGrey1 * nGrey2 / 255);
+        mEraseColor = Color(nGrey, nGrey, nGrey);
+        DataChanged();
+        SAL_INFO("vcl.skia.trace",
+                 "alphablendwith(" << this << ") : with erase color " << otherBitmap);
+        return true;
+    }
+    std::unique_ptr<SkiaSalBitmap> otherBitmapAllocated;
+    if (otherBitmap->GetBitCount() != 8 || !otherBitmap->mPalette.IsGreyPalette8Bit())
+    { // Convert/interpret as 8bit if needed.
+        otherBitmapAllocated = std::make_unique<SkiaSalBitmap>();
+        if (!otherBitmapAllocated->Create(*otherBitmap) || !otherBitmapAllocated->InterpretAs8Bit())
+            return false;
+        otherBitmap = otherBitmapAllocated.get();
+    }
+    // This is 8-bit bitmap serving as mask, so the image itself needs no alpha.
+    sk_sp<SkSurface> surface = createSkSurface(mSize, kOpaque_SkAlphaType);
+    SkPaint paint;
+    paint.setBlendMode(SkBlendMode::kSrc); // set as is
+    surface->getCanvas()->drawImage(GetSkImage(), 0, 0, SkSamplingOptions(), &paint);
+    paint.setBlendMode(SkBlendMode::kScreen); // src+dest - src*dest/255 (in 0..1)
+    surface->getCanvas()->drawImage(otherBitmap->GetSkImage(), 0, 0, SkSamplingOptions(), &paint);
+    ResetToSkImage(makeCheckedImageSnapshot(surface));
+    DataChanged();
+    SAL_INFO("vcl.skia.trace", "alphablendwith(" << this << ") : with image " << otherBitmap);
+    return true;
+}
+
+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 (!bitmap.installPixels(
+                    SkImageInfo::MakeS32(mPixelsSize.Width(), mPixelsSize.Height(), alphaType()),
+                    data.release(), mScanlineSize,
+                    [](void* addr, void*) { delete[] static_cast<sal_uInt8*>(addr); }, nullptr))
+                abort();
+        }
+        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();
+            // SkConvertRGBToRGBA() 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).
+            if (mPixelsSize.Width() * 3 == mScanlineSize)
+                SkConvertRGBToRGBA(dest, mBuffer.get(), mPixelsSize.Height() * mPixelsSize.Width());
+            else
+            {
+                for (tools::Long y = 0; y < mPixelsSize.Height(); ++y)
+                {
+                    const sal_uInt8* src = mBuffer.get() + mScanlineSize * y;
+                    SkConvertRGBToRGBA(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();
+        }
+        else if (mBitCount == 8 && mPalette.IsGreyPalette8Bit())
+        {
+            // Convert 8bpp gray to 32bpp RGBA/BGRA.
+            // There's also kGray_8_SkColorType, but it's probably simpler to make
+            // GetAsSkBitmap() always return 32bpp SkBitmap and then assume mImage
+            // is always 32bpp too.
+            std::unique_ptr<uint32_t[]> data(
+                new uint32_t[mPixelsSize.Height() * mPixelsSize.Width()]);
+            uint32_t* dest = data.get();
+            if (mPixelsSize.Width() * 1 == mScanlineSize)
+                SkConvertGrayToRGBA(dest, mBuffer.get(),
+                                    mPixelsSize.Height() * mPixelsSize.Width());
+            else
+            {
+                for (tools::Long y = 0; y < mPixelsSize.Height(); ++y)
+                {
+                    const sal_uInt8* src = mBuffer.get() + mScanlineSize * y;
+                    SkConvertGrayToRGBA(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();
+        }
+        else
+        {
+            std::unique_ptr<sal_uInt8[]> data = convertDataBitCount(
+                mBuffer.get(), mPixelsSize.Width(), mPixelsSize.Height(), mBitCount, mScanlineSize,
+                mPalette, kN32_SkColorTypeIsBGRA ? BitConvert::BGRA : BitConvert::RGBA);
+            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;
+}
+
+// If mEraseColor is set, this is the color to use when the bitmap is used as alpha bitmap.
+// E.g. COL_BLACK actually means fully opaque and COL_WHITE means fully transparent.
+// This is because the alpha value is set as the color itself, not the alpha of the color.
+// Additionally VCL actually uses transparency and not opacity, so we should use "255 - value",
+// but we account for this by doing SkBlendMode::kDstOut when using alpha images (which
+// basically does another "255 - alpha"), so do not do it here.
+static SkColor fromEraseColorToAlphaImageColor(Color color)
+{
+    return SkColorSetARGB(color.GetBlue(), 0, 0, 0);
+}
+
+// SkiaSalBitmap can store data in both the SkImage and our mBuffer, which with large
+// images can waste quite a lot of memory. Ideally we should store the data in Skia's
+// SkBitmap, but LO wants us to support data formats that Skia doesn't support.
+// So try to conserve memory by keeping the data only once in that was the most
+// recently wanted storage, and drop the other one. Usually the other one won't be needed
+// for a long time, and especially with raster the conversion is usually fast.
+// Do this only with raster, to avoid GPU->CPU transfer in GPU mode (exception is 32bit
+// builds, where memory is more important). Also don't do this with paletted bitmaps,
+// where EnsureBitmapData() would be expensive.
+// Ideally SalBitmap should be able to say which bitmap formats it supports
+// and VCL code should oblige, which would allow reusing the same data.
+bool SkiaSalBitmap::ConserveMemory() const
+{
+    static bool keepBitmapBuffer = getenv("SAL_SKIA_KEEP_BITMAP_BUFFER") != nullptr;
+    constexpr bool is32Bit = sizeof(void*) == 4;
+    // 16MiB bitmap data at least (set to 0 for easy testing).
+    constexpr tools::Long maxBufferSize = 2000 * 2000 * 4;
+    return !keepBitmapBuffer && (renderMethodToUse() == RenderRaster || is32Bit)
+           && mPixelsSize.Height() * mScanlineSize > maxBufferSize
+           && (mBitCount > 8 || (mBitCount == 8 && mPalette.IsGreyPalette8Bit()));
+}
+
+const sk_sp<SkImage>& SkiaSalBitmap::GetSkImage(DirectImage direct) const
+{
+#ifdef DBG_UTIL
+    assert(mWriteAccessCount == 0);
+#endif
+    if (direct == DirectImage::Yes)
+        return mImage;
+    if (mEraseColorSet)
+    {
+        if (mImage)
+        {
+            assert(imageSize(mImage) == mSize);
+            return mImage;
+        }
+        SkiaZone zone;
+        sk_sp<SkSurface> surface = createSkSurface(
+            mSize, mEraseColor.IsTransparent() ? kPremul_SkAlphaType : kOpaque_SkAlphaType);
+        assert(surface);
+        surface->getCanvas()->clear(toSkColor(mEraseColor));
+        SkiaSalBitmap* thisPtr = const_cast<SkiaSalBitmap*>(this);
+        thisPtr->mImage = makeCheckedImageSnapshot(surface);
+        SAL_INFO("vcl.skia.trace", "getskimage(" << this << ") from erase color " << mEraseColor);
+        return mImage;
+    }
+    if (mPixelsSize != mSize && !mImage && renderMethodToUse() != 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 = createSkImage(GetAsSkBitmap());
+        assert(image);
+        thisPtr->mSize = savedSize;
+        thisPtr->ResetToSkImage(image);
+    }
+    if (mImage)
+    {
+        if (imageSize(mImage) != mSize)
+        {
+            assert(!mBuffer); // This code should be only called if only mImage holds data.
+            SkiaZone zone;
+            sk_sp<SkSurface> surface = createSkSurface(mSize, mImage->imageInfo().alphaType());
+            assert(surface);
+            SkPaint paint;
+            paint.setBlendMode(SkBlendMode::kSrc); // set as is, including alpha
+            surface->getCanvas()->drawImageRect(
+                mImage, SkRect::MakeWH(mSize.Width(), mSize.Height()),
+                makeSamplingOptions(mScaleQuality, imageSize(mImage), mSize, 1), &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 = makeCheckedImageSnapshot(surface);
+        }
+        return mImage;
+    }
+    SkiaZone zone;
+    sk_sp<SkImage> image = createSkImage(GetAsSkBitmap());
+    assert(image);
+    SkiaSalBitmap* thisPtr = const_cast<SkiaSalBitmap*>(this);
+    thisPtr->mImage = image;
+    // The data is now stored both in the SkImage and in our mBuffer, so drop the buffer
+    // if conserving memory. It'll be converted back by EnsureBitmapData() if needed.
+    if (ConserveMemory() && mAnyAccessCount == 0)
+    {
+        SAL_INFO("vcl.skia.trace", "getskimage(" << this << "): dropping buffer");
+        thisPtr->ResetToSkImage(mImage);
+    }
+    SAL_INFO("vcl.skia.trace", "getskimage(" << this << ")");
+    return mImage;
+}
+
+const sk_sp<SkImage>& SkiaSalBitmap::GetAlphaSkImage(DirectImage direct) const
+{
+#ifdef DBG_UTIL
+    assert(mWriteAccessCount == 0);
+#endif
+    if (direct == DirectImage::Yes)
+        return mAlphaImage;
+    if (mEraseColorSet)
+    {
+        if (mAlphaImage)
+        {
+            assert(imageSize(mAlphaImage) == mSize);
+            return mAlphaImage;
+        }
+        SkiaZone zone;
+        sk_sp<SkSurface> surface = createSkSurface(mSize, kAlpha_8_SkColorType);
+        assert(surface);
+        surface->getCanvas()->clear(fromEraseColorToAlphaImageColor(mEraseColor));
+        SkiaSalBitmap* thisPtr = const_cast<SkiaSalBitmap*>(this);
+        thisPtr->mAlphaImage = makeCheckedImageSnapshot(surface);
+        SAL_INFO("vcl.skia.trace",
+                 "getalphaskimage(" << this << ") from erase color " << mEraseColor);
+        return mAlphaImage;
+    }
+    if (mAlphaImage)
+    {
+        if (imageSize(mAlphaImage) == mSize)
+            return mAlphaImage;
+    }
+    if (mImage)
+    {
+        SkiaZone zone;
+        const bool scaling = imageSize(mImage) != mSize;
+        SkPixmap pixmap;
+        // Note: We cannot do this when 'scaling' because SkCanvas::drawImageRect()
+        // with kAlpha_8_SkColorType as source and destination would act as SkBlendMode::kSrcOver
+        // despite SkBlendMode::kSrc set (https://bugs.chromium.org/p/skia/issues/detail?id=9692).
+        if (mImage->peekPixels(&pixmap) && !scaling)
+        {
+            assert(pixmap.colorType() == kN32_SkColorType);
+            // In non-GPU mode, convert 32bit data to 8bit alpha, this is faster than
+            // the SkColorFilter below. Since this is the VCL alpha-vdev alpha, where
+            // all R,G,B are the same and in fact mean alpha, this means we simply take one
+            // 8bit channel from the input, and that's the output.
+            SkBitmap bitmap;
+            if (!bitmap.installPixels(pixmap))
+                abort();
+            SkBitmap alphaBitmap;
+            if (!alphaBitmap.tryAllocPixels(SkImageInfo::MakeA8(bitmap.width(), bitmap.height())))
+                abort();
+            if (int(bitmap.rowBytes()) == bitmap.width() * 4)
+            {
+                SkConvertRGBAToR(alphaBitmap.getAddr8(0, 0), bitmap.getAddr32(0, 0),
+                                 bitmap.width() * bitmap.height());
+            }
+            else
+            {
+                for (tools::Long y = 0; y < bitmap.height(); ++y)
+                    SkConvertRGBAToR(alphaBitmap.getAddr8(0, y), bitmap.getAddr32(0, y),
+                                     bitmap.width());
+            }
+            alphaBitmap.setImmutable();
+            sk_sp<SkImage> alphaImage = createSkImage(alphaBitmap);
+            assert(alphaImage);
+            SAL_INFO("vcl.skia.trace", "getalphaskimage(" << this << ") from raster image");
+            // Don't bother here with ConserveMemory(), mImage -> mAlphaImage conversions should
+            // generally only happen with the separate-alpha-outdev hack, and those bitmaps should
+            // be temporary.
+            SkiaSalBitmap* thisPtr = const_cast<SkiaSalBitmap*>(this);
+            thisPtr->mAlphaImage = alphaImage;
+            return mAlphaImage;
+        }
+        // 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
+        SkPaint paint;
+        paint.setColorFilter(SkColorFilters::Matrix(redToAlpha));
+        if (scaling)
+            assert(!mBuffer); // This code should be only called if only mImage holds data.
+        sk_sp<SkSurface> surface = createSkSurface(mSize, kAlpha_8_SkColorType);
+        assert(surface);
+        paint.setBlendMode(SkBlendMode::kSrc); // set as is, including alpha
+        surface->getCanvas()->drawImageRect(
+            mImage, SkRect::MakeWH(mSize.Width(), mSize.Height()),
+            scaling ? makeSamplingOptions(mScaleQuality, imageSize(mImage), mSize, 1)
+                    : SkSamplingOptions(),
+            &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");
+        // Don't bother here with ConserveMemory(), mImage -> mAlphaImage conversions should
+        // generally only happen with the separate-alpha-outdev hack, and those bitmaps should
+        // be temporary.
+        SkiaSalBitmap* thisPtr = const_cast<SkiaSalBitmap*>(this);
+        thisPtr->mAlphaImage = 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 = createSkImage(alphaBitmap);
+        assert(image);
+        const_cast<sk_sp<SkImage>&>(mAlphaImage) = image;
+    }
+    else
+    {
+        sk_sp<SkSurface> surface = 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()->drawImage(GetAsSkBitmap().asImage(), 0, 0, SkSamplingOptions(),
+                                        &paint);
+        SkiaSalBitmap* thisPtr = const_cast<SkiaSalBitmap*>(this);
+        thisPtr->mAlphaImage = makeCheckedImageSnapshot(surface);
+    }
+    // The data is now stored both in the SkImage and in our mBuffer, so drop the buffer
+    // if conserving memory and the conversion back would be simple (it'll be converted back
+    // by EnsureBitmapData() if needed).
+    if (ConserveMemory() && mBitCount == 8 && mPalette.IsGreyPalette8Bit() && mAnyAccessCount == 0)
+    {
+        SAL_INFO("vcl.skia.trace", "getalphaskimage(" << this << "): dropping buffer");
+        SkiaSalBitmap* thisPtr = const_cast<SkiaSalBitmap*>(this);
+        thisPtr->mBuffer.reset();
+    }
+    SAL_INFO("vcl.skia.trace", "getalphaskimage(" << this << ")");
+    return mAlphaImage;
+}
+
+void SkiaSalBitmap::TryDirectConvertToAlphaNoScaling()
+{
+    // This is a bit of a hack. Because of the VCL alpha hack where alpha is stored
+    // separately, we often convert mImage to mAlphaImage to represent the alpha
+    // channel. If code finds out that there is mImage but no mAlphaImage,
+    // this will create it from it, without checking for delayed scaling (i.e.
+    // it is "direct").
+    assert(mImage);
+    assert(!mAlphaImage);
+    // Set wanted size, trigger conversion.
+    Size savedSize = mSize;
+    mSize = imageSize(mImage);
+    GetAlphaSkImage();
+    assert(mAlphaImage);
+    mSize = savedSize;
+}
+
+// If the bitmap is to be erased, SkShader with the color set is more efficient
+// than creating an image filled with the color.
+bool SkiaSalBitmap::PreferSkShader() const { return mEraseColorSet; }
+
+sk_sp<SkShader> SkiaSalBitmap::GetSkShader(const SkSamplingOptions& samplingOptions,
+                                           DirectImage direct) const
+{
+    if (mEraseColorSet)
+        return SkShaders::Color(toSkColor(mEraseColor));
+    return GetSkImage(direct)->makeShader(samplingOptions);
+}
+
+sk_sp<SkShader> SkiaSalBitmap::GetAlphaSkShader(const SkSamplingOptions& samplingOptions,
+                                                DirectImage direct) const
+{
+    if (mEraseColorSet)
+        return SkShaders::Color(fromEraseColorToAlphaImageColor(mEraseColor));
+    return GetAlphaSkImage(direct)->makeShader(samplingOptions);
+}
+
+bool SkiaSalBitmap::IsFullyOpaqueAsAlpha() const
+{
+    if (!mEraseColorSet) // Set from Erase() or ReleaseBuffer().
+        return false;
+    // If the erase color is set so that this bitmap used as alpha would
+    // mean a fully opaque alpha mask (= noop), we can skip using it.
+    // Note that for alpha bitmaps we use the VCL "transparency" convention,
+    // i.e. alpha 0 is opaque.
+    return SkColorGetA(fromEraseColorToAlphaImageColor(mEraseColor)) == 0;
+}
+
+SkAlphaType SkiaSalBitmap::alphaType() const
+{
+    if (mEraseColorSet)
+        return mEraseColor.IsTransparent() ? kPremul_SkAlphaType : kOpaque_SkAlphaType;
+#if SKIA_USE_BITMAP32
+    // The bitmap's alpha matters only if SKIA_USE_BITMAP32 is set, otherwise
+    // the alpha is in a separate bitmap.
+    if (mBitCount == 32)
+        return kPremul_SkAlphaType;
+#endif
+    return kOpaque_SkAlphaType;
+}
+
+void SkiaSalBitmap::PerformErase()
+{
+    if (mPixelsSize.IsEmpty())
+        return;
+    BitmapBuffer* bitmapBuffer = AcquireBuffer(BitmapAccessMode::Write);
+    if (bitmapBuffer == nullptr)
+        abort();
+    Color fastColor = mEraseColor;
+    if (!!mPalette)
+        fastColor = Color(ColorTransparency, mPalette.GetBestIndex(fastColor));
+    if (!ImplFastEraseBitmap(*bitmapBuffer, fastColor))
+    {
+        FncSetPixel setPixel = BitmapReadAccess::SetPixelFunction(bitmapBuffer->mnFormat);
+        assert(bitmapBuffer->mnFormat & ScanlineFormat::TopDown);
+        // Set first scanline, copy to others.
+        Scanline scanline = bitmapBuffer->mpBits;
+        for (tools::Long x = 0; x < bitmapBuffer->mnWidth; ++x)
+            setPixel(scanline, x, mEraseColor, bitmapBuffer->maColorMask);
+        for (tools::Long y = 1; y < bitmapBuffer->mnHeight; ++y)
+            memcpy(scanline + y * bitmapBuffer->mnScanlineSize, scanline,
+                   bitmapBuffer->mnScanlineSize);
+    }
+    ReleaseBuffer(bitmapBuffer, BitmapAccessMode::Write, true);
+}
+
+void SkiaSalBitmap::EnsureBitmapData()
+{
+    if (mEraseColorSet)
+    {
+        SkiaZone zone;
+        assert(mPixelsSize == mSize);
+        assert(!mBuffer);
+        CreateBitmapData();
+        // Unset now, so that repeated call will return mBuffer.
+        mEraseColorSet = false;
+        PerformErase();
+        verify();
+        SAL_INFO("vcl.skia.trace",
+                 "ensurebitmapdata(" << this << ") from erase color " << mEraseColor);
+        return;
+    }
+
+    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;
+    }
+
+    // Convert from alpha image, if the conversion is simple.
+    if (mAlphaImage && imageSize(mAlphaImage) == mSize && mBitCount == 8
+        && mPalette.IsGreyPalette8Bit())
+    {
+        assert(mAlphaImage->colorType() == kAlpha_8_SkColorType);
+        SkiaZone zone;
+        SkBitmap bitmap;
+        SkPixmap pixmap;
+        if (mAlphaImage->peekPixels(&pixmap))
+            bitmap.installPixels(pixmap);
+        else
+        {
+            if (!bitmap.tryAllocPixels(SkImageInfo::MakeA8(mSize.Width(), mSize.Height())))
+                abort();
+            SkCanvas canvas(bitmap);
+            SkPaint paint;
+            paint.setBlendMode(SkBlendMode::kSrc); // set as is, including alpha
+            canvas.drawImage(mAlphaImage, 0, 0, SkSamplingOptions(), &paint);
+            canvas.flush();
+        }
+        bitmap.setImmutable();
+        ResetPendingScaling();
+        CreateBitmapData();
+        assert(mBuffer != nullptr);
+        assert(mPixelsSize == mSize);
+        if (int(bitmap.rowBytes()) == mScanlineSize)
+            memcpy(mBuffer.get(), bitmap.getPixels(), mSize.Height() * mScanlineSize);
+        else
+        {
+            for (tools::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);
+            }
+        }
+        verify();
+        // We've created the bitmap data from mAlphaImage, drop the image if conserving memory,
+        // it'll be converted back if needed.
+        if (ConserveMemory())
+        {
+            SAL_INFO("vcl.skia.trace", "ensurebitmapdata(" << this << "): dropping images");
+            ResetToBuffer();
+        }
+        SAL_INFO("vcl.skia.trace", "ensurebitmapdata(" << this << "): from alpha image");
+        return;
+    }
+
+    if (!mImage)
+    {
+        // No data at all, create uninitialized data.
+        CreateBitmapData();
+        SAL_INFO("vcl.skia.trace", "ensurebitmapdata(" << this << "): uninitialized");
+        return;
+    }
+    // Try to fill mBuffer from mImage.
+    assert(mImage->colorType() == kN32_SkColorType);
+    SkiaZone zone;
+    // If the source image has no alpha, then use no alpha (faster to convert), otherwise
+    // use kUnpremul_SkAlphaType to make Skia convert from premultiplied alpha when reading
+    // from the SkImage (the alpha will be ignored if converting to bpp<32 formats, but
+    // the color channels must be unpremultiplied. Unless bpp==32 and SKIA_USE_BITMAP32,
+    // in which case use kPremul_SkAlphaType, since SKIA_USE_BITMAP32 implies premultiplied alpha.
+    SkAlphaType alphaType = kUnpremul_SkAlphaType;
+    if (mImage->imageInfo().alphaType() == kOpaque_SkAlphaType)
+        alphaType = kOpaque_SkAlphaType;
+#if SKIA_USE_BITMAP32
+    if (mBitCount == 32)
+        alphaType = kPremul_SkAlphaType;
+#endif
+    SkBitmap bitmap;
+    SkPixmap pixmap;
+    if (imageSize(mImage) == mSize && mImage->imageInfo().alphaType() == alphaType
+        && mImage->peekPixels(&pixmap))
+    {
+        bitmap.installPixels(pixmap);
+    }
+    else
+    {
+        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 (imageSize(mImage) != mSize) // pending scaling?
+        {
+            canvas.drawImageRect(mImage, SkRect::MakeWH(mSize.getWidth(), mSize.getHeight()),
+                                 makeSamplingOptions(mScaleQuality, imageSize(mImage), mSize, 1),
+                                 &paint);
+            SAL_INFO("vcl.skia.trace",
+                     "ensurebitmapdata(" << this << "): image scaled " << imageSize(mImage) << "->"
+                                         << mSize << ":" << static_cast<int>(mScaleQuality));
+        }
+        else
+            canvas.drawImage(mImage, 0, 0, SkSamplingOptions(), &paint);
+        canvas.flush();
+    }
+    bitmap.setImmutable();
+    ResetPendingScaling();
+    CreateBitmapData();
+    assert(mBuffer != nullptr);
+    assert(mPixelsSize == mSize);
+    if (mBitCount == 32)
+    {
+        if (int(bitmap.rowBytes()) == mScanlineSize)
+            memcpy(mBuffer.get(), bitmap.getPixels(), mSize.Height() * mScanlineSize);
+        else
+        {
+            for (tools::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
+    {
+        if (int(bitmap.rowBytes()) == mSize.Width() * 4 && mSize.Width() * 3 == mScanlineSize)
+        {
+            SkConvertRGBAToRGB(mBuffer.get(), bitmap.getAddr32(0, 0),
+                               mSize.Height() * mSize.Width());
+        }
+        else
+        {
+            for (tools::Long y = 0; y < mSize.Height(); ++y)
+            {
+                const uint32_t* src = bitmap.getAddr32(0, y);
+                sal_uInt8* dest = mBuffer.get() + mScanlineSize * y;
+                SkConvertRGBAToRGB(dest, src, mSize.Width());
+            }
+        }
+    }
+    else if (mBitCount == 8 && mPalette.IsGreyPalette8Bit())
+    { // no actual data conversion, use one color channel as the gray value
+        if (int(bitmap.rowBytes()) == mSize.Width() * 4 && mSize.Width() * 1 == mScanlineSize)
+        {
+            SkConvertRGBAToR(mBuffer.get(), bitmap.getAddr32(0, 0), mSize.Height() * mSize.Width());
+        }
+        else
+        {
+            for (tools::Long y = 0; y < mSize.Height(); ++y)
+            {
+                const uint32_t* src = bitmap.getAddr32(0, y);
+                sal_uInt8* dest = mBuffer.get() + mScanlineSize * y;
+                SkConvertRGBAToR(dest, src, mSize.Width());
+            }
+        }
+    }
+    else
+    {
+        std::unique_ptr<vcl::ScanlineWriter> pWriter
+            = vcl::ScanlineWriter::Create(mBitCount, mPalette);
+        for (tools::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 (tools::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();
+    // We've created the bitmap data from mImage, drop the image if conserving memory,
+    // it'll be converted back if needed.
+    if (ConserveMemory())
+    {
+        SAL_INFO("vcl.skia.trace", "ensurebitmapdata(" << this << "): dropping images");
+        ResetToBuffer();
+    }
+    SAL_INFO("vcl.skia.trace", "ensurebitmapdata(" << this << ")");
+}
+
+void SkiaSalBitmap::EnsureBitmapUniqueData()
+{
+#ifdef DBG_UTIL
+    assert(mWriteAccessCount == 0);
+#endif
+    EnsureBitmapData();
+    assert(mPixelsSize == mSize);
+    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::ResetToBuffer()
+{
+    SkiaZone zone;
+    // This should never be called to drop mImage if that's the only data we have.
+    assert(mBuffer || !mImage);
+    mImage.reset();
+    mAlphaImage.reset();
+    mEraseColorSet = false;
+}
+
+void SkiaSalBitmap::ResetToSkImage(sk_sp<SkImage> image)
+{
+    assert(mAnyAccessCount == 0); // can't reset mBuffer if there's a read access pointing to it
+    SkiaZone zone;
+    mBuffer.reset();
+    mImage = image;
+    mAlphaImage.reset();
+    mEraseColorSet = false;
+}
+
+void SkiaSalBitmap::ResetAllData()
+{
+    assert(mAnyAccessCount == 0);
+    SkiaZone zone;
+    mBuffer.reset();
+    mImage.reset();
+    mAlphaImage.reset();
+    mEraseColorSet = false;
+    mPixelsSize = mSize;
+    ComputeScanlineSize();
+    DataChanged();
+}
+
+void SkiaSalBitmap::DataChanged() { InvalidateChecksum(); }
+
+void SkiaSalBitmap::ResetPendingScaling()
+{
+    if (mPixelsSize == mSize)
+        return;
+    SkiaZone zone;
+    mScaleQuality = BmpScaleFlag::BestQuality;
+    mPixelsSize = mSize;
+    ComputeScanlineSize();
+    // Information about the pending scaling has been discarded, so make sure we do not
+    // keep around any cached images that would still need scaling.
+    if (mImage && imageSize(mImage) != mSize)
+        mImage.reset();
+    if (mAlphaImage && imageSize(mAlphaImage) != mSize)
+        mAlphaImage.reset();
+}
+
+OString SkiaSalBitmap::GetImageKey(DirectImage direct) const
+{
+    if (mEraseColorSet)
+    {
+        std::stringstream ss;
+        ss << std::hex << std::setfill('0') << std::setw(6)
+           << static_cast<sal_uInt32>(mEraseColor.GetRGBColor()) << std::setw(2)
+           << static_cast<int>(mEraseColor.GetAlpha());
+        return OString::Concat("E") + ss.str().c_str();
+    }
+    assert(direct == DirectImage::No || mImage);
+    sk_sp<SkImage> image = GetSkImage(direct);
+    // In some cases drawing code may try to draw the same content but using
+    // different bitmaps (even underlying bitmaps), for example canvas apparently
+    // copies the same things around in tdf#146095. For pixel-based images
+    // it should be still cheaper to compute a checksum and avoid re-caching.
+    if (!image->isTextureBacked())
+        return OString::Concat("C") + OString::number(getSkImageChecksum(image));
+    return OString::Concat("I") + OString::number(image->uniqueID());
+}
+
+OString SkiaSalBitmap::GetAlphaImageKey(DirectImage direct) const
+{
+    if (mEraseColorSet)
+    {
+        std::stringstream ss;
+        ss << std::hex << std::setfill('0') << std::setw(2)
+           << static_cast<int>(255 - SkColorGetA(fromEraseColorToAlphaImageColor(mEraseColor)));
+        return OString::Concat("E") + ss.str().c_str();
+    }
+    assert(direct == DirectImage::No || mAlphaImage);
+    sk_sp<SkImage> image = GetAlphaSkImage(direct);
+    if (!image->isTextureBacked())
+        return OString::Concat("C") + OString::number(getSkImageChecksum(image));
+    return OString::Concat("I") + OString::number(image->uniqueID());
+}
+
+void SkiaSalBitmap::dump(const char* file) const
+{
+    // Use a copy, so that debugging doesn't affect this instance.
+    SkiaSalBitmap copy;
+    copy.Create(*this);
+    SkiaHelper::dump(copy.GetSkImage(), file);
+}
+
+#ifdef DBG_UTIL
+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: */