cc: Async readback.

cc/output/gl_renderer.cc

 // Copyright 2010 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/gl_renderer.h"
 
 #include <algorithm>
 #include <set>
 #include <string>
 #include <vector>
@@ skipping 1745 matching lines @@
 
 void GLRenderer::EnsureScissorTestDisabled() {
   if (!is_scissor_enabled_)
     return;
 
   FlushTextureQuadCache();
   GLC(context_, context_->disable(GL_SCISSOR_TEST));
   is_scissor_enabled_ = false;
 }
 
+void GLRenderer::CopyCurrentRenderPassToBitmap(DrawingFrame* frame,
+                                               SkBitmap* bitmap) {
+  gfx::Size render_pass_size = frame->current_render_pass->output_rect.size();
+  bitmap->setConfig(SkBitmap::kARGB_8888_Config,
+                    render_pass_size.width(),
+                    render_pass_size.height());
+  if (bitmap->allocPixels()) {
+    bitmap->lockPixels();
+    GetFramebufferPixels(bitmap->getPixels(), gfx::Rect(render_pass_size));

[piman, 2013/04/25 02:13:52]

How hard would it be to add the flexibility, and asyncness of
GLHelper::CopyTextureToImpl::CropScaleReadbackAndCleanTexture ?

GPU scale is needed on at least some chrome OS devices (Alex at least? Probably
Pixel too) to avoid hundreds of ms jank in the GPU process - reading back the
entire buffer is just too much.
The asyncness is to avoid janking the compositor thread itself, because
readPixels is essentially a glFinish, so it has to wait for GPU process
completion, and it breaks pipelining (the tab capture guys want to do this every
frame).

[danakj, 2013/04/25 18:39:15]

Flexibility is fine, pass around a struct with more params than a callback
alone. I'll do that in a separate followup with tests.
The asyncyness I need to understand better, but also seems totally fine. Also
will do as a followup.

+    bitmap->unlockPixels();
+  }
+}
+
 void GLRenderer::ToGLMatrix(float* gl_matrix, const gfx::Transform& transform) {
   transform.matrix().asColMajorf(gl_matrix);
 }
 
 void GLRenderer::SetShaderQuadF(const gfx::QuadF& quad, int quad_location) {
   if (quad_location == -1)
     return;
 
   float point[8];
   point[0] = quad.p1().x();
@@ skipping 795 matching lines @@
     resource_provider_->DeleteResource(on_demand_tile_raster_resource_id_);
 
   ReleaseRenderPassTextures();
 }
 
 bool GLRenderer::IsContextLost() {
   return (context_->getGraphicsResetStatusARB() != GL_NO_ERROR);
 }
 
 }  // namespace cc