Enable fast/images with slimming paint

Source/core/paint/BoxPainter.cpp

 // Copyright 2014 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 "config.h"
 #include "core/paint/BoxPainter.h"
 
 #include "core/HTMLNames.h"
 #include "core/frame/Settings.h"
 #include "core/html/HTMLFrameOwnerElement.h"
 #include "core/paint/BackgroundImageGeometry.h"
 #include "core/paint/BoxDecorationData.h"
 #include "core/paint/DrawingRecorder.h"
+#include "core/paint/TransparencyDisplayItem.h"
 #include "core/rendering/ImageQualityController.h"
 #include "core/rendering/PaintInfo.h"
 #include "core/rendering/RenderBox.h"
 #include "core/rendering/RenderBoxModelObject.h"
 #include "core/rendering/RenderLayer.h"
 #include "core/rendering/RenderObject.h"
 #include "core/rendering/RenderTable.h"
 #include "core/rendering/RenderTheme.h"
 #include "core/rendering/RenderView.h"
 #include "core/rendering/compositing/CompositedLayerMapping.h"
@@ skipping 484 matching lines @@
     if (!paintInfo.shouldPaintWithinRoot(&m_renderBox) || m_renderBox.style()->visibility() != VISIBLE || paintInfo.phase != PaintPhaseMask)
         return;
 
     LayoutRect paintRect = LayoutRect(paintOffset, m_renderBox.size());
     paintMaskImages(paintInfo, paintRect);
 }
 
 void BoxPainter::paintMaskImages(const PaintInfo& paintInfo, const LayoutRect& paintRect)
 {
     // Figure out if we need to push a transparency layer to render our mask.
-    bool pushTransparencyLayer = false;
+    OwnPtr<TransparencyRecorder> transparencyRecorder;
     bool compositedMask = m_renderBox.hasLayer() && m_renderBox.layer()->hasCompositedMask();
     bool flattenCompositingLayers = m_renderBox.view()->frameView() && m_renderBox.view()->frameView()->paintBehavior() & PaintBehaviorFlattenCompositingLayers;
     CompositeOperator compositeOp = CompositeSourceOver;
 
     bool allMaskImagesLoaded = true;
 
     if (!compositedMask || flattenCompositingLayers) {
-        pushTransparencyLayer = true;
         StyleImage* maskBoxImage = m_renderBox.style()->maskBoxImage().image();
         const FillLayer& maskLayers = m_renderBox.style()->maskLayers();
 
         // Don't render a masked element until all the mask images have loaded, to prevent a flash of unmasked content.
         if (maskBoxImage)
             allMaskImagesLoaded &= maskBoxImage->isLoaded();
 
         allMaskImagesLoaded &= maskLayers.imagesAreLoaded();
 
         paintInfo.context->setCompositeOperation(CompositeDestinationIn);

[chrishtr, 2014/11/21 20:08:26]

This line needs to be in a display item of some kind. Not this one?

-        paintInfo.context->beginTransparencyLayer(1);
+
+        transparencyRecorder = adoptPtr(new TransparencyRecorder(paintInfo.context, &m_renderBox, DisplayItem::BeginTransparency,
+            paintRect, m_renderBox.style()->blendMode(), 1, TransparencyClipBehavior::DoNotClip));
+
         compositeOp = CompositeSourceOver;
     }
 
     if (allMaskImagesLoaded) {
         paintFillLayers(paintInfo, Color::transparent, m_renderBox.style()->maskLayers(), paintRect, BackgroundBleedNone, compositeOp);
         paintNinePieceImage(m_renderBox, paintInfo.context, paintRect, m_renderBox.style(), m_renderBox.style()->maskBoxImage(), compositeOp);
     }
-
-    if (pushTransparencyLayer)
-        paintInfo.context->endLayer();
 }
 
 void BoxPainter::paintClippingMask(const PaintInfo& paintInfo, const LayoutPoint& paintOffset)
 {
     if (!paintInfo.shouldPaintWithinRoot(&m_renderBox) || m_renderBox.style()->visibility() != VISIBLE || paintInfo.phase != PaintPhaseClippingMask)
         return;
 
     if (!m_renderBox.layer() || m_renderBox.layer()->compositingState() != PaintsIntoOwnBacking)
         return;
 
@@ skipping 1602 matching lines @@
 
     FloatPoint secondQuad[4];
     secondQuad[0] = quad[0];
     secondQuad[1] = FloatPoint(quad[0].x() - r1 * cx, quad[0].y() - r1 * cy);
     secondQuad[2] = quad[2];
     secondQuad[3] = quad[3];
     graphicsContext->clipPolygon(4, secondQuad, !secondEdgeMatches);
 }
 
 } // namespace blink