skia::AnalysisCanvas: implementation for 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 82 matching lines @@
   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) {

[Sami, 2013/02/04 10:57:54]

Should we make this a const method?

[Tom Hudson, 2013/02/05 17:02:00]

Done.

I also had to add contents_scale to the list of args so that the AnalysisCanvas
would line up with the real canvas in Raster().

+  skia::AnalysisCanvas canvas(gfx::RectToSkRect(layer_rect));
+  // If a picture has estimatd cost below this threshold, go ahead and
+  // wait until we have more pictures to draw (to amortize startup costs).
+  // If cost exceeds this threshold, start it now so we aren't blocked
+  // waiting for it.
+  // FIXME: Arbitrary number. Requires tuning & experimentation.
+  // Probably requires per-platform tuning; N10 average draw call takes
+  // 25x as long as Z620.
+  int pictureCostThreshold = 100;
+  canvas.drawPicture(*picture_);
+  if (canvas.getEstimatedCost() <= pictureCostThreshold) {

[nduca, 2013/02/04 10:34:33]

love this. convert this to bool isCheap() and push the threshold to analyscanvas
maybe? That way we dont have to instantiate a cc picture in order to unit test
it.

[Tom Hudson, 2013/02/05 17:02:00]

Done.

+    return true;
+  }
   return false;
 }
 
 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(),
@@ skipping 12 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