1 files changed, 139 insertions, 0 deletions
diff --git a/gfx/layers/ScreenshotGrabber.h b/gfx/layers/ScreenshotGrabber.h
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+++ b/gfx/layers/ScreenshotGrabber.h
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+/* -*- 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/. */
+
+#ifndef mozilla_layers_ScreenshotGrabber_h
+#define mozilla_layers_ScreenshotGrabber_h
+
+#include "nsISupportsImpl.h"
+#include "mozilla/RefPtr.h"
+#include "mozilla/UniquePtr.h"
+#include "mozilla/gfx/2D.h"
+#include "mozilla/gfx/Point.h"
+#include "mozilla/gfx/Rect.h"
+
+namespace mozilla {
+namespace layers {
+
+namespace profiler_screenshots {
+class Window;
+class RenderSource;
+class DownscaleTarget;
+class AsyncReadbackBuffer;
+
+class ScreenshotGrabberImpl;
+}  // namespace profiler_screenshots
+
+/**
+ * Used by various renderers / layer managers to grab snapshots from the window
+ * and submit them to the Gecko profiler.
+ * Doesn't do any work if the profiler is not running or the "screenshots"
+ * feature is not enabled.
+ * Screenshots are scaled down to fit within a fixed size, and read back to
+ * main memory using async readback. Scaling is done in multiple scale-by-0.5x
+ * steps using DownscaleTarget::CopyFrom, and readback is done using
+ * AsyncReadbackBuffers.
+ */
+class ScreenshotGrabber final {
+ public:
+  ScreenshotGrabber();
+  ~ScreenshotGrabber();
+
+  // Scale the contents of aWindow's current render target into an
+  // appropriately sized DownscaleTarget and read its contents into an
+  // AsyncReadbackBuffer. The AsyncReadbackBuffer is not mapped into main
+  // memory until the second call to MaybeProcessQueue() after this call to
+  // MaybeGrabScreenshot().
+  void MaybeGrabScreenshot(profiler_screenshots::Window& aWindow,
+                           const gfx::IntSize& aWindowSize);
+
+  // Map the contents of any outstanding AsyncReadbackBuffers from previous
+  // composites into main memory and submit each screenshot to the profiler.
+  void MaybeProcessQueue();
+
+  // Insert a special profiler marker for a composite that didn't do any actual
+  // compositing, so that the profiler knows why no screenshot was taken for
+  // this frame.
+  void NotifyEmptyFrame();
+
+  // Destroy all Window-related resources that this class is holding on to.
+  void Destroy();
+
+ private:
+  // non-null while ProfilerScreenshots::IsEnabled() returns true
+  UniquePtr<profiler_screenshots::ScreenshotGrabberImpl> mImpl;
+};
+
+// Interface definitions.
+
+namespace profiler_screenshots {
+
+class Window {
+ public:
+  virtual already_AddRefed<RenderSource> GetWindowContents(
+      const gfx::IntSize& aWindowSize) = 0;
+  virtual already_AddRefed<DownscaleTarget> CreateDownscaleTarget(
+      const gfx::IntSize& aSize) = 0;
+  virtual already_AddRefed<AsyncReadbackBuffer> CreateAsyncReadbackBuffer(
+      const gfx::IntSize& aSize) = 0;
+
+ protected:
+  virtual ~Window() {}
+};
+
+class RenderSource {
+ public:
+  NS_INLINE_DECL_THREADSAFE_REFCOUNTING(RenderSource)
+
+  const auto& Size() const { return mSize; }
+
+ protected:
+  explicit RenderSource(const gfx::IntSize& aSize) : mSize(aSize) {}
+  virtual ~RenderSource() {}
+
+  const gfx::IntSize mSize;
+};
+
+class DownscaleTarget {
+ public:
+  NS_INLINE_DECL_THREADSAFE_REFCOUNTING(DownscaleTarget)
+
+  virtual already_AddRefed<RenderSource> AsRenderSource() = 0;
+
+  const auto& Size() const { return mSize; }
+  virtual bool DownscaleFrom(RenderSource* aSource,
+                             const gfx::IntRect& aSourceRect,
+                             const gfx::IntRect& aDestRect) = 0;
+
+ protected:
+  explicit DownscaleTarget(const gfx::IntSize& aSize) : mSize(aSize) {}
+  virtual ~DownscaleTarget() {}
+
+  const gfx::IntSize mSize;
+};
+
+class AsyncReadbackBuffer {
+ public:
+  NS_INLINE_DECL_THREADSAFE_REFCOUNTING(
+      mozilla::layers::profiler_screenshots::AsyncReadbackBuffer)
+
+  const auto& Size() const { return mSize; }
+  virtual void CopyFrom(RenderSource* aSource) = 0;
+  virtual bool MapAndCopyInto(gfx::DataSourceSurface* aSurface,
+                              const gfx::IntSize& aReadSize) = 0;
+
+ protected:
+  explicit AsyncReadbackBuffer(const gfx::IntSize& aSize) : mSize(aSize) {}
+  virtual ~AsyncReadbackBuffer() {}
+
+  const gfx::IntSize mSize;
+};
+
+}  // namespace profiler_screenshots
+
+}  // namespace layers
+}  // namespace mozilla
+
+#endif  // mozilla_layers_ScreenshotGrabber_h