Bug 1585619 - Add option of using PrintWindow() for taking snapshot of DirectComposition r=gw

Differential Revision: https://phabricator.services.mozilla.com/D47894

--HG--
extra : moz-landing-system : lando

gfx/webrender_bindings/DCLayerTree.cpp

@@ -126,6 +126,10 @@ void DCLayerTree::MaybeUpdateDebug() {
   }
 }
 
+void DCLayerTree::WaitForCommitCompletion() {
+  mCompositionDevice->WaitForCommitCompletion();
+}
+
 bool DCLayerTree::MaybeUpdateDebugCounter() {
   bool debugCounter = StaticPrefs::gfx_webrender_debug_dcomp_counter();
   if (mDebugCounter == debugCounter) {

gfx/webrender_bindings/DCLayerTree.h

@@ -53,6 +53,7 @@ class DCLayerTree {
 
   void SetDefaultSwapChain(IDXGISwapChain1* aSwapChain);
   void MaybeUpdateDebug();
+  void WaitForCommitCompletion();
 
   // Interface for wr::Compositor
   void CompositorBeginFrame();
@@ -164,6 +165,7 @@ class DCLayerTree {
   }
   void SetDefaultSwapChain(IDXGISwapChain1* aSwapChain) {}
   void MaybeUpdateDebug() {}
+  void WaitForCommitCompletion() {}
 
   // Interface for wr::Compositor
   void CompositorBeginFrame() {}

gfx/webrender_bindings/RenderCompositor.h

@@ -99,6 +99,14 @@ class RenderCompositor {
   // Whether the surface origin is top-left.
   virtual bool SurfaceOriginIsTopLeft() { return false; }
 
+  // Does readback if wr_renderer_readback() could not get correct WR rendered
+  // result. It could happen when WebRender renders to multiple overlay layers.
+  virtual bool MaybeReadback(const gfx::IntSize& aReadbackSize,
+                             const wr::ImageFormat& aReadbackFormat,
+                             const Range<uint8_t>& aReadbackBuffer) {
+    return false;
+  }
+
  protected:
   // We default this to 2, so that mLatestRenderFrameId.Prev() is always valid.
   RenderedFrameId mLatestRenderFrameId = RenderedFrameId{2};

gfx/webrender_bindings/RenderCompositorANGLE.cpp

@@ -30,6 +30,12 @@
 #include <dcomp.h>
 #include <dxgi1_2.h>
 
+// Flag for PrintWindow() that is defined in Winuser.h. It is defined since
+// Windows 8.1. This allows PrintWindow to capture window content that is
+// rendered with DirectComposition.
+#undef PW_RENDERFULLCONTENT
+#define PW_RENDERFULLCONTENT 0x00000002
+
 namespace mozilla {
 namespace wr {
 
@@ -777,5 +783,70 @@ uint32_t RenderCompositorANGLE::GetMaxPartialPresentRects() {
   return StaticPrefs::gfx_webrender_max_partial_present_rects_AtStartup();
 }
 
+bool RenderCompositorANGLE::MaybeReadback(
+    const gfx::IntSize& aReadbackSize, const wr::ImageFormat& aReadbackFormat,
+    const Range<uint8_t>& aReadbackBuffer) {
+  MOZ_ASSERT(aReadbackFormat == wr::ImageFormat::BGRA8);
+
+  if (!UseCompositor()) {
+    return false;
+  }
+
+  HDC nulldc = ::GetDC(NULL);
+  HDC dc = ::CreateCompatibleDC(nulldc);
+  ::ReleaseDC(nullptr, nulldc);
+  if (!dc) {
+    gfxCriticalError() << "CreateCompatibleDC failed";
+    return false;
+  }
+
+  BITMAPV4HEADER header;
+  memset(&header, 0, sizeof(BITMAPV4HEADER));
+  header.bV4Size = sizeof(BITMAPV4HEADER);
+  header.bV4Width = aReadbackSize.width;
+  header.bV4Height = -LONG(aReadbackSize.height);  // top-to-buttom DIB
+  header.bV4Planes = 1;
+  header.bV4BitCount = 32;
+  header.bV4V4Compression = BI_BITFIELDS;
+  header.bV4RedMask = 0x00FF0000;
+  header.bV4GreenMask = 0x0000FF00;
+  header.bV4BlueMask = 0x000000FF;
+  header.bV4AlphaMask = 0xFF000000;
+
+  void* readbackBits = nullptr;
+  HBITMAP bitmap =
+      ::CreateDIBSection(dc, reinterpret_cast<BITMAPINFO*>(&header),
+                         DIB_RGB_COLORS, &readbackBits, nullptr, 0);
+  if (!bitmap) {
+    ::DeleteDC(dc);
+    gfxCriticalError() << "CreateDIBSection failed";
+    return false;
+  }
+
+  ::SelectObject(dc, bitmap);
+
+  UINT flags = PW_CLIENTONLY | PW_RENDERFULLCONTENT;
+  HWND hwnd = mWidget->AsWindows()->GetHwnd();
+
+  mDCLayerTree->WaitForCommitCompletion();
+
+  BOOL result = ::PrintWindow(hwnd, dc, flags);
+  if (!result) {
+    ::DeleteObject(bitmap);
+    ::DeleteDC(dc);
+    gfxCriticalError() << "PrintWindow failed";
+    return false;
+  }
+
+  ::GdiFlush();
+
+  memcpy(&aReadbackBuffer[0], readbackBits, aReadbackBuffer.length());
+
+  ::DeleteObject(bitmap);
+  ::DeleteDC(dc);
+
+  return true;
+}
+
 }  // namespace wr
 }  // namespace mozilla

gfx/webrender_bindings/RenderCompositorANGLE.h

@@ -83,6 +83,10 @@ class RenderCompositorANGLE : public RenderCompositor {
   bool RequestFullRender() override;
   uint32_t GetMaxPartialPresentRects() override;
 
+  bool MaybeReadback(const gfx::IntSize& aReadbackSize,
+                     const wr::ImageFormat& aReadbackFormat,
+                     const Range<uint8_t>& aReadbackBuffer) override;
+
  protected:
   bool UseCompositor();
   void InitializeUsePartialPresent();

gfx/webrender_bindings/RendererOGL.cpp

@@ -159,10 +159,13 @@ RenderedFrameId RendererOGL::UpdateAndRender(
   if (aReadbackBuffer.isSome()) {
     MOZ_ASSERT(aReadbackSize.isSome());
     MOZ_ASSERT(aReadbackFormat.isSome());
-    wr_renderer_readback(mRenderer, aReadbackSize.ref().width,
-                         aReadbackSize.ref().height, aReadbackFormat.ref(),
-                         &aReadbackBuffer.ref()[0],
-                         aReadbackBuffer.ref().length());
+    if (!mCompositor->MaybeReadback(aReadbackSize.ref(), aReadbackFormat.ref(),
+                                    aReadbackBuffer.ref())) {
+      wr_renderer_readback(mRenderer, aReadbackSize.ref().width,
+                           aReadbackSize.ref().height, aReadbackFormat.ref(),
+                           &aReadbackBuffer.ref()[0],
+                           aReadbackBuffer.ref().length());
+    }
   }
 
   mScreenshotGrabber.MaybeGrabScreenshot(mRenderer, size.ToUnknownSize());