80% of calls to skia::GetTopDevice() were retrieving a read-only reference to the raw pixel data; this CL simplifies those call sites and migrates to a more GPU-friendly and less internals-exposing implementation.

BUG=543755

Review URL: https://codereview.chromium.org/1399223004

Cr-Commit-Position: refs/heads/master@{#355104}

3 files changed, 15 insertions, 2 deletions

diff --git a/skia/ext/platform_canvas.cc b/skia/ext/platform_canvas.cc
index 778ee09..5e5aeb2 100644
--- a/skia/ext/platform_canvas.cc
+++ b/skia/ext/platform_canvas.cc
@@ -13,6 +13,13 @@ SkBaseDevice* GetTopDevice(const SkCanvas& canvas) {
   return canvas.getTopDevice(true);
 }
 
+SkBitmap ReadPixels(SkCanvas* canvas) {
+  SkBitmap bitmap;
+  bitmap.setInfo(canvas->imageInfo());
+  canvas->readPixels(&bitmap, 0, 0);
+  return bitmap;
+}
+
 bool SupportsPlatformPaint(const SkCanvas* canvas) {
   PlatformDevice* platform_device = GetPlatformDevice(GetTopDevice(*canvas));
   return platform_device && platform_device->SupportsPlatformPaint();
diff --git a/skia/ext/platform_canvas.h b/skia/ext/platform_canvas.h
index 79c10fd..4499041 100644
--- a/skia/ext/platform_canvas.h
+++ b/skia/ext/platform_canvas.h
@@ -116,6 +116,13 @@ SK_API size_t PlatformCanvasStrideForWidth(unsigned width);
 // by the next call to save() or restore().
 SK_API SkBaseDevice* GetTopDevice(const SkCanvas& canvas);
 
+// Copies pixels from the SkCanvas into an SkBitmap, fetching pixels from
+// GPU memory if necessary.
+//
+// The bitmap will remain empty if we can't allocate enough memory for a copy
+// of the pixels.
+SK_API SkBitmap ReadPixels(SkCanvas* canvas);
+
 // Returns true if native platform routines can be used to draw on the
 // given canvas. If this function returns false, BeginPlatformPaint will
 // return NULL PlatformSurface.
diff --git a/skia/ext/platform_canvas_unittest.cc b/skia/ext/platform_canvas_unittest.cc
index cb2862f..a4a2ff5 100644
--- a/skia/ext/platform_canvas_unittest.cc
+++ b/skia/ext/platform_canvas_unittest.cc
@@ -42,8 +42,7 @@ bool IsOfColor(const SkBitmap& bitmap, int x, int y, uint32_t color) {
 bool VerifyRect(const PlatformCanvas& canvas,
                 uint32_t canvas_color, uint32_t rect_color,
                 int x, int y, int w, int h) {
-  SkBaseDevice* device = skia::GetTopDevice(canvas);
-  const SkBitmap& bitmap = device->accessBitmap(false);
+  const SkBitmap bitmap = skia::ReadPixels(const_cast<PlatformCanvas*>(&canvas));
   SkAutoLockPixels lock(bitmap);
 
   for (int cur_y = 0; cur_y < bitmap.height(); cur_y++) {