cc: Do GatherPixelRefs from skia at record time

cc/resources/picture.cc

Index: cc/resources/picture.cc
diff --git a/cc/resources/picture.cc b/cc/resources/picture.cc
index 2b6eca8777fbc0c3d7d280170d3f7008ce85d990..2fc4fee798c27cf83f03bc1c26d5ed323e02cbd1 100644
--- a/cc/resources/picture.cc
+++ b/cc/resources/picture.cc
@@ -2,10 +2,14 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+#include "cc/resources/picture.h"
+
+#include <algorithm>
+#include <set>
+
 #include "base/debug/trace_event.h"
 #include "cc/debug/rendering_stats.h"
 #include "cc/layers/content_layer_client.h"
-#include "cc/resources/picture.h"
 #include "skia/ext/analysis_canvas.h"
 #include "third_party/skia/include/core/SkCanvas.h"
 #include "third_party/skia/include/core/SkData.h"
@@ -44,10 +48,12 @@ Picture::Picture(gfx::Rect layer_rect)
 
 Picture::Picture(const skia::RefPtr<SkPicture>& picture,
                  gfx::Rect layer_rect,
-                 gfx::Rect opaque_rect) :
+                 gfx::Rect opaque_rect,
+                 const PositionPixelRefsVector& lazy_pixel_refs) :
     layer_rect_(layer_rect),
     opaque_rect_(opaque_rect),
-    picture_(picture) {
+    picture_(picture),
+    lazy_pixel_refs_(lazy_pixel_refs) {
 }
 
 Picture::~Picture() {
@@ -73,7 +79,8 @@ void Picture::CloneForDrawing(int num_threads) {
     scoped_refptr<Picture> clone = make_scoped_refptr(
         new Picture(skia::AdoptRef(new SkPicture(clones[i])),
                     layer_rect_,
-                    opaque_rect_));
+                    opaque_rect_,
+                    lazy_pixel_refs_));
     clones_.push_back(clone);
   }
 }
@@ -125,6 +132,8 @@ void Picture::Record(ContentLayerClient* painter,
   picture_->endRecording();
 
   opaque_rect_ = gfx::ToEnclosedRect(opaque_layer_rect);
+
+  GatherAllPixelRefs();
 }
 
 void Picture::Raster(
@@ -152,6 +161,26 @@ void Picture::Raster(
 
 void Picture::GatherPixelRefs(const gfx::Rect& layer_rect,
                               std::list<skia::LazyPixelRef*>& pixel_ref_list) {
+  std::list<skia::LazyPixelRef*> pixel_refs;
+  for (PositionPixelRefsVector::iterator iter = lazy_pixel_refs_.begin();
+      iter != lazy_pixel_refs_.end();
+      ++iter) {
+    if (iter->rect.Intersects(layer_rect)) {
+      pixel_refs.insert(pixel_refs.end(),
+                        iter->pixel_refs.begin(),
+                        iter->pixel_refs.end());
+    }
+  }
+  std::set<skia::LazyPixelRef*> unique_pixel_refs(pixel_refs.begin(),
+                                                  pixel_refs.end());
+  pixel_ref_list.insert(pixel_ref_list.end(),
+                        unique_pixel_refs.begin(),
+                        unique_pixel_refs.end());
+}
+
+void Picture::GatherPixelRefsFromSkia(
+    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(),
@@ -178,4 +207,33 @@ void Picture::GatherPixelRefs(const gfx::Rect& layer_rect,
   pixel_refs->unref();
 }
 
+void Picture::GatherAllPixelRefs() {
+  const gfx::Size kRegionSize(512, 512);
+  // Capture pixel refs for this picture in a grid
+  // with kRegionSize sized cells.
+  for (int y = layer_rect_.y();
+      y < layer_rect_.bottom();
+      y += kRegionSize.height()) {
+    for (int x = layer_rect_.x();
+        x < layer_rect_.right();
+        x += kRegionSize.width()) {
+      gfx::Size extent(
+          std::min(kRegionSize.width(), layer_rect_.right() - x),
+          std::min(kRegionSize.height(), layer_rect_.bottom() - y));
+      gfx::Rect rect(x, y, extent.width(), extent.height());

[enne (OOO), 2013/04/16 22:03:36]

Can we get this information from Skia, rather than trying to guess what rect
this image takes up?

[reveman, 2013/04/17 00:25:28]

this is not related to the image size. it's the grid size used for storing pixel
refs. we should probably use PicturePileBase::tile_grid_info_.fTileInterval here
as that's probably what will be used if we move this to skia.

+
+      std::list<skia::LazyPixelRef*> lazy_pixel_refs;
+      GatherPixelRefsFromSkia(rect, lazy_pixel_refs);
+
+      // Only capture non-empty cells.
+      if (!lazy_pixel_refs.empty()) {
+        PositionPixelRefs position_pixel_refs;
+        position_pixel_refs.rect = rect;
+        position_pixel_refs.pixel_refs.swap(lazy_pixel_refs);
+        lazy_pixel_refs_.push_back(position_pixel_refs);
+      }
+    }
+  }
+}
+
 }  // namespace cc