1 files changed, 229 insertions, 0 deletions
diff --git a/gfx/layers/ScreenshotGrabber.cpp b/gfx/layers/ScreenshotGrabber.cpp
new file mode 100644
index 0000000000..3719afa336
--- /dev/null
+++ b/gfx/layers/ScreenshotGrabber.cpp
@@ -0,0 +1,229 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* 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 "ScreenshotGrabber.h"
+
+#include "mozilla/ProfilerMarkers.h"
+#include "mozilla/RefPtr.h"
+#include "mozilla/TimeStamp.h"
+#include "mozilla/UniquePtr.h"
+
+#include "mozilla/layers/Compositor.h"
+#include "mozilla/layers/ProfilerScreenshots.h"
+#include "mozilla/layers/TextureHost.h"
+#include "mozilla/gfx/Point.h"
+#include "nsTArray.h"
+
+namespace mozilla {
+
+using namespace gfx;
+
+namespace layers {
+namespace profiler_screenshots {
+
+/**
+ * The actual implementation of screenshot grabbing.
+ * The ScreenshotGrabberImpl object is destroyed if the profiler is
+ * disabled and MaybeGrabScreenshot notices it.
+ */
+class ScreenshotGrabberImpl final {
+ public:
+  explicit ScreenshotGrabberImpl(const IntSize& aBufferSize);
+  ~ScreenshotGrabberImpl();
+
+  void GrabScreenshot(Window& aWindow, const IntSize& aWindowSize);
+  void ProcessQueue();
+
+ private:
+  struct QueueItem final {
+    mozilla::TimeStamp mTimeStamp;
+    RefPtr<AsyncReadbackBuffer> mScreenshotBuffer;
+    IntSize mScreenshotSize;
+    IntSize mWindowSize;
+  };
+
+  RefPtr<RenderSource> ScaleDownWindowRenderSourceToSize(
+      Window& aWindow, const IntSize& aDestSize,
+      RenderSource* aWindowRenderSource, size_t aLevel);
+
+  already_AddRefed<AsyncReadbackBuffer> TakeNextBuffer(Window& aWindow);
+  void ReturnBuffer(AsyncReadbackBuffer* aBuffer);
+
+  nsTArray<RefPtr<DownscaleTarget>> mCachedLevels;
+  nsTArray<RefPtr<AsyncReadbackBuffer>> mAvailableBuffers;
+  Maybe<QueueItem> mCurrentFrameQueueItem;
+  nsTArray<QueueItem> mQueue;
+  RefPtr<ProfilerScreenshots> mProfilerScreenshots;
+  const IntSize mBufferSize;
+};
+
+}  // namespace profiler_screenshots
+
+ScreenshotGrabber::ScreenshotGrabber() = default;
+
+ScreenshotGrabber::~ScreenshotGrabber() = default;
+
+void ScreenshotGrabber::MaybeGrabScreenshot(
+    profiler_screenshots::Window& aWindow, const IntSize& aWindowSize) {
+  if (ProfilerScreenshots::IsEnabled()) {
+    if (!mImpl) {
+      mImpl = MakeUnique<profiler_screenshots::ScreenshotGrabberImpl>(
+          ProfilerScreenshots::ScreenshotSize());
+    }
+    mImpl->GrabScreenshot(aWindow, aWindowSize);
+  } else if (mImpl) {
+    Destroy();
+  }
+}
+
+void ScreenshotGrabber::MaybeProcessQueue() {
+  if (ProfilerScreenshots::IsEnabled()) {
+    if (!mImpl) {
+      mImpl = MakeUnique<profiler_screenshots::ScreenshotGrabberImpl>(
+          ProfilerScreenshots::ScreenshotSize());
+    }
+    mImpl->ProcessQueue();
+  } else if (mImpl) {
+    Destroy();
+  }
+}
+
+void ScreenshotGrabber::NotifyEmptyFrame() {
+  PROFILER_MARKER_UNTYPED("NoCompositorScreenshot because nothing changed",
+                          GRAPHICS);
+}
+
+void ScreenshotGrabber::Destroy() { mImpl = nullptr; }
+
+namespace profiler_screenshots {
+
+ScreenshotGrabberImpl::ScreenshotGrabberImpl(const IntSize& aBufferSize)
+    : mBufferSize(aBufferSize) {}
+
+ScreenshotGrabberImpl::~ScreenshotGrabberImpl() {
+  // Any queue items in mQueue or mCurrentFrameQueueItem will be lost.
+  // That's ok: Either the profiler has stopped and we don't care about these
+  // screenshots, or the window is closing and we don't really need the last
+  // few frames from the window.
+}
+
+// Scale down aWindowRenderSource into a RenderSource of size
+// mBufferSize * (1 << aLevel) and return that RenderSource.
+// Don't scale down by more than a factor of 2 with a single scaling operation,
+// because it'll look bad. If higher scales are needed, use another
+// intermediate target by calling this function recursively with aLevel + 1.
+RefPtr<RenderSource> ScreenshotGrabberImpl::ScaleDownWindowRenderSourceToSize(
+    Window& aWindow, const IntSize& aDestSize,
+    RenderSource* aWindowRenderSource, size_t aLevel) {
+  if (aLevel == mCachedLevels.Length()) {
+    mCachedLevels.AppendElement(
+        aWindow.CreateDownscaleTarget(mBufferSize * (1 << aLevel)));
+  }
+  MOZ_RELEASE_ASSERT(aLevel < mCachedLevels.Length());
+
+  RefPtr<RenderSource> renderSource = aWindowRenderSource;
+  IntSize sourceSize = aWindowRenderSource->Size();
+  if (sourceSize.width > aDestSize.width * 2) {
+    sourceSize = aDestSize * 2;
+    renderSource = ScaleDownWindowRenderSourceToSize(
+        aWindow, sourceSize, aWindowRenderSource, aLevel + 1);
+  }
+
+  if (renderSource) {
+    if (mCachedLevels[aLevel]->DownscaleFrom(
+            renderSource, IntRect({}, sourceSize), IntRect({}, aDestSize))) {
+      return mCachedLevels[aLevel]->AsRenderSource();
+    }
+  }
+  return nullptr;
+}
+
+void ScreenshotGrabberImpl::GrabScreenshot(Window& aWindow,
+                                           const IntSize& aWindowSize) {
+  RefPtr<RenderSource> windowRenderSource =
+      aWindow.GetWindowContents(aWindowSize);
+
+  if (!windowRenderSource) {
+    PROFILER_MARKER_UNTYPED(
+        "NoCompositorScreenshot because of unsupported compositor "
+        "configuration",
+        GRAPHICS);
+    return;
+  }
+
+  Size windowSize(aWindowSize);
+  float scale = std::min(mBufferSize.width / windowSize.width,
+                         mBufferSize.height / windowSize.height);
+  IntSize scaledSize = IntSize::Round(windowSize * scale);
+  RefPtr<RenderSource> scaledTarget = ScaleDownWindowRenderSourceToSize(
+      aWindow, scaledSize, windowRenderSource, 0);
+
+  if (!scaledTarget) {
+    PROFILER_MARKER_UNTYPED(
+        "NoCompositorScreenshot because ScaleDownWindowRenderSourceToSize "
+        "failed",
+        GRAPHICS);
+    return;
+  }
+
+  RefPtr<AsyncReadbackBuffer> buffer = TakeNextBuffer(aWindow);
+  if (!buffer) {
+    PROFILER_MARKER_UNTYPED(
+        "NoCompositorScreenshot because AsyncReadbackBuffer creation failed",
+        GRAPHICS);
+    return;
+  }
+
+  buffer->CopyFrom(scaledTarget);
+
+  // This QueueItem will be added to the queue at the end of the next call to
+  // ProcessQueue(). This ensures that the buffer isn't mapped into main memory
+  // until the next frame. If we did it in this frame, we'd block on the GPU.
+  mCurrentFrameQueueItem =
+      Some(QueueItem{TimeStamp::Now(), std::move(buffer), scaledSize,
+                     windowRenderSource->Size()});
+}
+
+already_AddRefed<AsyncReadbackBuffer> ScreenshotGrabberImpl::TakeNextBuffer(
+    Window& aWindow) {
+  if (!mAvailableBuffers.IsEmpty()) {
+    RefPtr<AsyncReadbackBuffer> buffer = mAvailableBuffers[0];
+    mAvailableBuffers.RemoveElementAt(0);
+    return buffer.forget();
+  }
+  return aWindow.CreateAsyncReadbackBuffer(mBufferSize);
+}
+
+void ScreenshotGrabberImpl::ReturnBuffer(AsyncReadbackBuffer* aBuffer) {
+  mAvailableBuffers.AppendElement(aBuffer);
+}
+
+void ScreenshotGrabberImpl::ProcessQueue() {
+  if (!mQueue.IsEmpty()) {
+    if (!mProfilerScreenshots) {
+      mProfilerScreenshots = new ProfilerScreenshots();
+    }
+    for (const auto& item : mQueue) {
+      mProfilerScreenshots->SubmitScreenshot(
+          item.mWindowSize, item.mScreenshotSize, item.mTimeStamp,
+          [&item](DataSourceSurface* aTargetSurface) {
+            return item.mScreenshotBuffer->MapAndCopyInto(aTargetSurface,
+                                                          item.mScreenshotSize);
+          });
+      ReturnBuffer(item.mScreenshotBuffer);
+    }
+  }
+  mQueue.Clear();
+
+  if (mCurrentFrameQueueItem) {
+    mQueue.AppendElement(std::move(*mCurrentFrameQueueItem));
+    mCurrentFrameQueueItem = Nothing();
+  }
+}
+
+}  // namespace profiler_screenshots
+}  // namespace layers
+}  // namespace mozilla