Optimize alpha software PictureDrawQuads.

cc/output/software_renderer.cc

 // Copyright 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "cc/output/software_renderer.h"
 
 #include "base/debug/trace_event.h"
 #include "cc/base/math_util.h"
 #include "cc/output/compositor_frame.h"
 #include "cc/output/compositor_frame_ack.h"
 #include "cc/output/compositor_frame_metadata.h"
 #include "cc/output/copy_output_request.h"
 #include "cc/output/output_surface.h"
 #include "cc/output/software_output_device.h"
 #include "cc/quads/checkerboard_draw_quad.h"
 #include "cc/quads/debug_border_draw_quad.h"
 #include "cc/quads/picture_draw_quad.h"
 #include "cc/quads/render_pass_draw_quad.h"
 #include "cc/quads/solid_color_draw_quad.h"
 #include "cc/quads/texture_draw_quad.h"
 #include "cc/quads/tile_draw_quad.h"
-#include "third_party/skia/include/core/SkBitmapDevice.h"
+#include "skia/ext/opacity_draw_filter.h"
 #include "third_party/skia/include/core/SkCanvas.h"
 #include "third_party/skia/include/core/SkColor.h"
 #include "third_party/skia/include/core/SkMatrix.h"
 #include "third_party/skia/include/core/SkShader.h"
 #include "third_party/skia/include/effects/SkLayerRasterizer.h"
 #include "ui/gfx/rect_conversions.h"
 #include "ui/gfx/skia_util.h"
 #include "ui/gfx/transform.h"
 
 namespace cc {
@@ skipping 271 matching lines @@
 
 void SoftwareRenderer::DrawPictureQuad(const DrawingFrame* frame,
                                        const PictureDrawQuad* quad) {
   SkMatrix content_matrix;
   content_matrix.setRectToRect(
       gfx::RectFToSkRect(quad->tex_coord_rect),
       gfx::RectFToSkRect(QuadVertexRect()),
       SkMatrix::kFill_ScaleToFit);
   current_canvas_->concat(content_matrix);
 
-  if (quad->ShouldDrawWithBlending()) {
-    TRACE_EVENT0("cc", "SoftwareRenderer::DrawPictureQuad with blending");
-    SkBitmap temp_bitmap;
-    temp_bitmap.setConfig(SkBitmap::kARGB_8888_Config,
-                          quad->texture_size.width(),
-                          quad->texture_size.height());
-    temp_bitmap.allocPixels();
-    SkBitmapDevice temp_device(temp_bitmap);
-    SkCanvas temp_canvas(&temp_device);
+  // http://crbug.com/280374 - Applying opacity to each individual draw call is

[joth, 2013/08/28 03:29:12]

Is this a TODO, or an explanation of what is already done? (I think the former,
but at first it reads like the latter)

+  // often incorrect. We should detect these cases and fall back to a persistent
+  // bitmap backing.
+  current_canvas_->setDrawFilter(new skia::OpacityDrawFilter(quad->opacity(),
+                                                             true));
 
-    quad->picture_pile->RasterToBitmap(
-        &temp_canvas, quad->content_rect, quad->contents_scale, NULL);
+  TRACE_EVENT0("cc",
+               "SoftwareRenderer::DrawPictureQuad");
+  quad->picture_pile->RasterDirect(
+      current_canvas_, quad->content_rect, quad->contents_scale, NULL);
 
-    current_paint_.setFilterBitmap(true);
-    current_canvas_->drawBitmap(temp_bitmap, 0, 0, &current_paint_);
-  } else {
-    TRACE_EVENT0("cc",
-                 "SoftwareRenderer::DrawPictureQuad direct from PicturePile");
-    quad->picture_pile->RasterDirect(
-        current_canvas_, quad->content_rect, quad->contents_scale, NULL);
-  }
+  current_canvas_->setDrawFilter(NULL);
 }
 
 void SoftwareRenderer::DrawSolidColorQuad(const DrawingFrame* frame,
                                           const SolidColorDrawQuad* quad) {
   current_paint_.setColor(quad->color);
   current_paint_.setAlpha(quad->opacity() * SkColorGetA(quad->color));
   current_canvas_->drawRect(gfx::RectFToSkRect(QuadVertexRect()),
                             current_paint_);
 }
 
@@ skipping 192 matching lines @@
     EnsureBackbuffer();
   else
     DiscardBackbuffer();
 }
 
 void SoftwareRenderer::SetDiscardBackBufferWhenNotVisible(bool discard) {
   // The software renderer always discards the backbuffer when not visible.
 }
 
 }  // namespace cc