Use SkSrc_Mode in SkCanvasVideoRenderer, to prevent transparent video frames from blending with reused image buffer contents.

BUG=392733
TEST=SkCanvasVideoRendererTest.TransparentFrame

Review URL: https://codereview.chromium.org/388363002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@283338 0039d316-1c4b-4281-b951-d872f2087c98

4 files changed, 39 insertions, 0 deletions

diff --git a/media/base/video_frame.cc b/media/base/video_frame.cc
index 74e6cae..f6b49e4 100644
--- a/media/base/video_frame.cc
+++ b/media/base/video_frame.cc
@@ -372,6 +372,19 @@ scoped_refptr<VideoFrame> VideoFrame::CreateBlackFrame(const gfx::Size& size) {
   return CreateColorFrame(size, kBlackY, kBlackUV, kBlackUV, kZero);
 }
 
+// static
+scoped_refptr<VideoFrame> VideoFrame::CreateTransparentFrame(
+    const gfx::Size& size) {
+  const uint8 kBlackY = 0x00;
+  const uint8 kBlackUV = 0x00;
+  const uint8 kTransparentA = 0x00;
+  const base::TimeDelta kZero;
+  scoped_refptr<VideoFrame> frame = VideoFrame::CreateFrame(
+      VideoFrame::YV12A, size, gfx::Rect(size), size, kZero);
+  FillYUVA(frame, kBlackY, kBlackUV, kBlackUV, kTransparentA);
+  return frame;
+}
+
 #if defined(VIDEO_HOLE)
 // This block and other blocks wrapped around #if defined(VIDEO_HOLE) is not
 // maintained by the general compositor team. Please contact the following
diff --git a/media/base/video_frame.h b/media/base/video_frame.h
index 8a607e0..2445dd1 100644
--- a/media/base/video_frame.h
+++ b/media/base/video_frame.h
@@ -189,6 +189,11 @@ class MEDIA_EXPORT VideoFrame : public base::RefCountedThreadSafe<VideoFrame> {
   // equivalent of RGB(0,0,0).
   static scoped_refptr<VideoFrame> CreateBlackFrame(const gfx::Size& size);
 
+  // Allocates YV12A frame based on |size|, and sets its data to the YUVA
+  // equivalent of RGBA(0,0,0,0).
+  static scoped_refptr<VideoFrame> CreateTransparentFrame(
+      const gfx::Size& size);
+
 #if defined(VIDEO_HOLE)
   // Allocates a hole frame.
   static scoped_refptr<VideoFrame> CreateHoleFrame(const gfx::Size& size);
diff --git a/media/base/video_util.cc b/media/base/video_util.cc
index 09f37b8..d794674 100644
--- a/media/base/video_util.cc
+++ b/media/base/video_util.cc
@@ -96,6 +96,20 @@ void FillYUV(VideoFrame* frame, uint8 y, uint8 u, uint8 v) {
   }
 }
 
+void FillYUVA(VideoFrame* frame, uint8 y, uint8 u, uint8 v, uint8 a) {
+  // Fill Y, U and V planes.
+  FillYUV(frame, y, u, v);
+
+  // Fill the A plane.
+  uint8* a_plane = frame->data(VideoFrame::kAPlane);
+  int a_rows = frame->rows(VideoFrame::kAPlane);
+  int a_row_bytes = frame->row_bytes(VideoFrame::kAPlane);
+  for (int i = 0; i < a_rows; ++i) {
+    memset(a_plane, a, a_row_bytes);
+    a_plane += frame->stride(VideoFrame::kAPlane);
+  }
+}
+
 static void LetterboxPlane(VideoFrame* frame,
                            int plane,
                            const gfx::Rect& view_area,
diff --git a/media/base/video_util.h b/media/base/video_util.h
index 5788015..702e620 100644
--- a/media/base/video_util.h
+++ b/media/base/video_util.h
@@ -44,6 +44,13 @@ MEDIA_EXPORT void CopyPlane(size_t plane, const uint8* source, int stride,
 // Fills |frame| containing YUV data to the given color values.
 MEDIA_EXPORT void FillYUV(VideoFrame* frame, uint8 y, uint8 u, uint8 v);
 
+// Fills |frame| containing YUVA data with the given color values.
+MEDIA_EXPORT void FillYUVA(VideoFrame* frame,
+                           uint8 y,
+                           uint8 u,
+                           uint8 v,
+                           uint8 a);
+
 // Creates a border in |frame| such that all pixels outside of
 // |view_area| are black. The size and position of |view_area|
 // must be even to align correctly with the color planes.