Implementation for cc::Picture::IsCheapInRect().

cc/picture.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 "base/debug/trace_event.h"
 #include "cc/content_layer_client.h"
 #include "cc/picture.h"
 #include "cc/rendering_stats.h"
+#include "skia/ext/analysis_canvas.h"
 #include "third_party/skia/include/core/SkCanvas.h"
 #include "third_party/skia/include/core/SkData.h"
 #include "third_party/skia/include/core/SkTileGridPicture.h"
 #include "third_party/skia/include/utils/SkPictureUtils.h"
 #include "ui/gfx/rect_conversions.h"
 #include "ui/gfx/skia_util.h"
 
 namespace {
 // URI label for a lazily decoded SkPixelRef.
 const char labelLazyDecoded[] = "lazy";
@@ skipping 75 matching lines @@
   picture_->endRecording();
 
   opaque_rect_ = gfx::ToEnclosedRect(opaque_layer_rect);
 }
 
 void Picture::Raster(
     SkCanvas* canvas,
     gfx::Rect content_rect,
     float contents_scale) {
   TRACE_EVENT2("cc", "Picture::Raster",
-               "width", layer_rect_.width(), "height", layer_rect_.height());
+               "layer width", layer_rect_.width(),
+               "layer height", layer_rect_.height());
   DCHECK(picture_);
 
   canvas->save();
   canvas->clipRect(gfx::RectToSkRect(content_rect));
   canvas->scale(contents_scale, contents_scale);
   canvas->translate(layer_rect_.x(), layer_rect_.y());
   canvas->drawPicture(*picture_);
   canvas->restore();
 }
 
 bool Picture::IsCheapInRect(const gfx::Rect& layer_rect) {
-  return false;
+  TRACE_EVENT0("cc", "Picture::IsCheapInRect");
+
+  SkBitmap emptyBitmap;
+  emptyBitmap.setConfig(SkBitmap::kNo_Config, layer_rect.width(),
+                        layer_rect.height());
+  skia::AnalysisDevice device(emptyBitmap);
+  skia::AnalysisCanvas canvas(&device);
+
+  canvas.drawPicture(*picture_);
+  return canvas.isCheap();
 }
 
 void Picture::GatherPixelRefs(const gfx::Rect& layer_rect,
                               std::list<skia::LazyPixelRef*>& pixel_ref_list) {
   DCHECK(picture_);
   SkData* pixel_refs = SkPictureUtils::GatherPixelRefs(
       picture_.get(), SkRect::MakeXYWH(layer_rect.x(),
                                        layer_rect.y(),
                                        layer_rect.width(),
                                        layer_rect.height()));
@@ skipping 11 matching lines @@
     if (*refs && (*refs)->getURI() && !strncmp(
         (*refs)->getURI(), labelLazyDecoded, 4)) {
       pixel_ref_list.push_back(static_cast<skia::LazyPixelRef*>(*refs));
     }
     refs++;
   }
   pixel_refs->unref();
 }
 
 }  // namespace cc