cc: Support anti-aliasing for solid color layers.

cc/solid_color_layer_impl.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/solid_color_layer_impl.h"
 
+#include "cc/math_util.h"
 #include "cc/quad_sink.h"
 #include "cc/solid_color_draw_quad.h"
+#include "ui/gfx/quad_f.h"
 
 namespace cc {
 
 SolidColorLayerImpl::SolidColorLayerImpl(LayerTreeImpl* treeImpl, int id)
     : LayerImpl(treeImpl, id)
     , m_tileSize(256)
 {
 }
 
 SolidColorLayerImpl::~SolidColorLayerImpl()
 {
 }
 
 void SolidColorLayerImpl::appendQuads(QuadSink& quadSink, AppendQuadsData& appendQuadsData)
 {
     SharedQuadState* sharedQuadState = quadSink.useSharedQuadState(createSharedQuadState());
     appendDebugBorderQuad(quadSink, sharedQuadState, appendQuadsData);
 
     // We create a series of smaller quads instead of just one large one so that the
     // culler can reduce the total pixels drawn.
     int width = contentBounds().width();
     int height = contentBounds().height();
     for (int x = 0; x < width; x += m_tileSize) {
         for (int y = 0; y < height; y += m_tileSize) {
             gfx::Rect solidTileRect(x, y, std::min(width - x, m_tileSize), std::min(height - y, m_tileSize));
+
+            bool clipped = false;
+            gfx::QuadF visibleContentInTargetQuad = MathUtil::mapQuad(drawTransform(), gfx::QuadF(visibleContentRect()), clipped);
+            bool isAxisAlignedInTarget = !clipped && visibleContentInTargetQuad.IsRectilinear();
+            bool useAA = !isAxisAlignedInTarget;
+
+            bool leftEdgeAA = !x && useAA;
+            bool topEdgeAA = !y && useAA;
+            bool rightEdgeAA = x >= width - m_tileSize && useAA;
+            bool bottomEdgeAA = y >= height - m_tileSize && useAA;
+
             scoped_ptr<SolidColorDrawQuad> quad = SolidColorDrawQuad::Create();
-            quad->SetNew(sharedQuadState, solidTileRect, backgroundColor());
+            quad->SetNew(sharedQuadState, solidTileRect, DrawQuad::AntiAliasing(leftEdgeAA, topEdgeAA, rightEdgeAA, bottomEdgeAA), backgroundColor());
             quadSink.append(quad.PassAs<DrawQuad>(), appendQuadsData);
         }
     }
 }
 
 const char* SolidColorLayerImpl::layerTypeAsString() const
 {
     return "SolidColorLayer";
 }
 
 }  // namespace cc