ObjectPainter::paintAsStackingContext()

third_party/WebKit/Source/core/paint/SVGForeignObjectPainter.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 "core/paint/SVGForeignObjectPainter.h"
 
 #include "core/layout/svg/LayoutSVGForeignObject.h"
 #include "core/layout/svg/SVGLayoutSupport.h"
 #include "core/paint/BlockPainter.h"
 #include "core/paint/FloatClipRecorder.h"
+#include "core/paint/ObjectPainter.h"
 #include "core/paint/PaintInfo.h"
 #include "core/paint/SVGPaintContext.h"
 #include "core/paint/TransformRecorder.h"
 #include "wtf/Optional.h"
 
 namespace blink {
 
+namespace {
+
+class BlockPainterDelegate : public LayoutBlock {
+public:
+    BlockPainterDelegate(const LayoutSVGForeignObject& layoutSVGForeignObject)
+        : LayoutBlock(nullptr)
+        , m_layoutSVGForeignObject(layoutSVGForeignObject)
+    { }
+
+private:
+    void paint(const PaintInfo& paintInfo, const LayoutPoint& paintOffset) const final
+    {
+        BlockPainter(m_layoutSVGForeignObject).paint(paintInfo, paintOffset);
+    }
+    const LayoutSVGForeignObject& m_layoutSVGForeignObject;
+};
+
+} // namespace
+
 void SVGForeignObjectPainter::paint(const PaintInfo& paintInfo)
 {
     if (paintInfo.phase != PaintPhaseForeground && paintInfo.phase != PaintPhaseSelection)
         return;
 
     PaintInfo paintInfoBeforeFiltering(paintInfo);
     paintInfoBeforeFiltering.updateCullRect(m_layoutSVGForeignObject.localTransform());
     TransformRecorder transformRecorder(paintInfoBeforeFiltering.context, m_layoutSVGForeignObject, m_layoutSVGForeignObject.localTransform());
 
     Optional<FloatClipRecorder> clipRecorder;
     if (SVGLayoutSupport::isOverflowHidden(&m_layoutSVGForeignObject))
         clipRecorder.emplace(paintInfoBeforeFiltering.context, m_layoutSVGForeignObject, paintInfoBeforeFiltering.phase, m_layoutSVGForeignObject.viewportRect());
 
     SVGPaintContext paintContext(m_layoutSVGForeignObject, paintInfoBeforeFiltering);
     bool continueRendering = true;
     if (paintContext.paintInfo().phase == PaintPhaseForeground)
         continueRendering = paintContext.applyClipMaskAndFilterIfNecessary();
 
     if (continueRendering) {
         // Paint all phases of FO elements atomically as though the FO element established its own stacking context.
-        bool preservePhase = paintContext.paintInfo().phase == PaintPhaseSelection || paintContext.paintInfo().phase == PaintPhaseTextClip;
-        const LayoutPoint childPoint = IntPoint();
-        paintContext.paintInfo().phase = preservePhase ? paintContext.paintInfo().phase : PaintPhaseBlockBackground;
-        BlockPainter(m_layoutSVGForeignObject).paint(paintContext.paintInfo(), childPoint);
-        if (!preservePhase) {
-            paintContext.paintInfo().phase = PaintPhaseChildBlockBackgrounds;
-            BlockPainter(m_layoutSVGForeignObject).paint(paintContext.paintInfo(), childPoint);
-            paintContext.paintInfo().phase = PaintPhaseFloat;
-            BlockPainter(m_layoutSVGForeignObject).paint(paintContext.paintInfo(), childPoint);
-            paintContext.paintInfo().phase = PaintPhaseForeground;
-            BlockPainter(m_layoutSVGForeignObject).paint(paintContext.paintInfo(), childPoint);
-            paintContext.paintInfo().phase = PaintPhaseOutline;
-            BlockPainter(m_layoutSVGForeignObject).paint(paintContext.paintInfo(), childPoint);
-        }
+        BlockPainterDelegate delegate(m_layoutSVGForeignObject);

[chrishtr, 2016/01/07 01:51:26]

What prevents you from just calling
BlockPainter(m_layoutSVGForeignObject).paintAsStackingContext?

[Xianzhu, 2016/01/07 17:02:40]

It would call m_layoutSVGForeignObject.paint() again and cause infinite
recursion. SVGForeignObjectPainter::paint() should call BlockPainter::paint()
when doing paintAsPseudoStackingContext(). The delegate helps it to do this.

Added comment.

+        ObjectPainter(delegate).paintAsStackingContext(paintContext.paintInfo(), LayoutPoint());
     }
 }
 
 } // namespace blink