Refactor ClipPathHelper in PaintLayerPainter.cpp for reuse

third_party/WebKit/Source/core/paint/PaintLayerPainter.cpp

Index: third_party/WebKit/Source/core/paint/PaintLayerPainter.cpp
diff --git a/third_party/WebKit/Source/core/paint/PaintLayerPainter.cpp b/third_party/WebKit/Source/core/paint/PaintLayerPainter.cpp
index 86176fa7819076bb8bebf5db97cc9b96570ad85a..4ba639057b55dfaf7d409fd972e006304c9f5482 100644
--- a/third_party/WebKit/Source/core/paint/PaintLayerPainter.cpp
+++ b/third_party/WebKit/Source/core/paint/PaintLayerPainter.cpp
@@ -4,27 +4,20 @@
 
 #include "core/paint/PaintLayerPainter.h"
 
-#include "core/frame/FrameView.h"
-#include "core/frame/Settings.h"
-#include "core/layout/LayoutBlock.h"
+#include "core/frame/LocalFrame.h"
 #include "core/layout/LayoutView.h"
-#include "core/layout/svg/LayoutSVGResourceClipper.h"
-#include "core/page/Page.h"
+#include "core/paint/ClipPathClipper.h"
 #include "core/paint/FilterPainter.h"
 #include "core/paint/LayerClipRecorder.h"
 #include "core/paint/ObjectPaintProperties.h"
 #include "core/paint/PaintInfo.h"
 #include "core/paint/PaintLayer.h"
-#include "core/paint/SVGClipPainter.h"
 #include "core/paint/ScrollRecorder.h"
 #include "core/paint/ScrollableAreaPainter.h"
 #include "core/paint/Transform3DRecorder.h"
-#include "core/style/ClipPathOperation.h"
 #include "platform/RuntimeEnabledFeatures.h"
 #include "platform/geometry/FloatPoint3D.h"
 #include "platform/graphics/GraphicsLayer.h"
-#include "platform/graphics/paint/ClipPathRecorder.h"
-#include "platform/graphics/paint/ClipRecorder.h"
 #include "platform/graphics/paint/CompositingRecorder.h"
 #include "platform/graphics/paint/DisplayItemCacheSkipper.h"
 #include "platform/graphics/paint/PaintChunkProperties.h"
@@ -120,73 +113,6 @@ PaintLayerPainter::PaintResult PaintLayerPainter::paintLayerContentsAndReflectio
     return result;
 }
 
-class ClipPathHelper {
-public:
-    ClipPathHelper(GraphicsContext& context, const PaintLayer& paintLayer, PaintLayerPaintingInfo& paintingInfo, LayoutRect& rootRelativeBounds, bool& rootRelativeBoundsComputed,
-        const LayoutPoint& offsetFromRoot, PaintLayerFlags paintFlags)
-        : m_resourceClipper(0), m_paintLayer(paintLayer), m_context(context)
-    {
-        const ComputedStyle& style = paintLayer.layoutObject()->styleRef();
-
-        // Clip-path, like border radius, must not be applied to the contents of a composited-scrolling container.
-        // It must, however, still be applied to the mask layer, so that the compositor can properly mask the
-        // scrolling contents and scrollbars.
-        if (!paintLayer.layoutObject()->hasClipPath() || (paintLayer.needsCompositedScrolling() && !(paintFlags & PaintLayerPaintingChildClippingMaskPhase)))
-            return;
-
-        m_clipperState = SVGClipPainter::ClipperNotApplied;
-
-        paintingInfo.ancestorHasClipPathClipping = true;
-
-        ASSERT(style.clipPath());
-        if (style.clipPath()->type() == ClipPathOperation::SHAPE) {
-            ShapeClipPathOperation* clipPath = toShapeClipPathOperation(style.clipPath());
-            if (clipPath->isValid()) {
-                if (!rootRelativeBoundsComputed) {
-                    rootRelativeBounds = paintLayer.physicalBoundingBoxIncludingReflectionAndStackingChildren(offsetFromRoot);
-                    rootRelativeBoundsComputed = true;
-                }
-                m_clipPathRecorder.emplace(context, *paintLayer.layoutObject(), clipPath->path(FloatRect(rootRelativeBounds)));
-            }
-        } else if (style.clipPath()->type() == ClipPathOperation::REFERENCE) {
-            ReferenceClipPathOperation* referenceClipPathOperation = toReferenceClipPathOperation(style.clipPath());
-            Document& document = paintLayer.layoutObject()->document();
-            // FIXME: It doesn't work with forward or external SVG references (https://bugs.webkit.org/show_bug.cgi?id=90405)
-            Element* element = document.getElementById(referenceClipPathOperation->fragment());
-            if (isSVGClipPathElement(element) && element->layoutObject()) {
-                if (!rootRelativeBoundsComputed) {
-                    rootRelativeBounds = paintLayer.physicalBoundingBoxIncludingReflectionAndStackingChildren(offsetFromRoot);
-                    rootRelativeBoundsComputed = true;
-                }
-
-                m_resourceClipper = toLayoutSVGResourceClipper(toLayoutSVGResourceContainer(element->layoutObject()));
-                // When SVG applies the clip and the coordinate system is "user space on use", we must explicitly pass in
-                // the layer offset to have the clip paint in the correct location. When the coordinate system is
-                // "object bounding box" the offset is already accounted for in the rootRelativeBounds.
-                FloatPoint layerPositionOffset = m_resourceClipper->clipPathUnits() == SVGUnitTypes::kSvgUnitTypeUserspaceonuse ?
-                    FloatPoint(offsetFromRoot) : FloatPoint();
-                if (!SVGClipPainter(*m_resourceClipper).prepareEffect(*paintLayer.layoutObject(), FloatRect(rootRelativeBounds),
-                    FloatRect(rootRelativeBounds), layerPositionOffset, context, m_clipperState)) {
-                    // No need to post-apply the clipper if this failed.
-                    m_resourceClipper = 0;
-                }
-            }
-        }
-    }
-
-    ~ClipPathHelper()
-    {
-        if (m_resourceClipper)
-            SVGClipPainter(*m_resourceClipper).finishEffect(*m_paintLayer.layoutObject(), m_context, m_clipperState);
-    }
-private:
-    LayoutSVGResourceClipper* m_resourceClipper;
-    Optional<ClipPathRecorder> m_clipPathRecorder;
-    SVGClipPainter::ClipperState m_clipperState;
-    const PaintLayer& m_paintLayer;
-    GraphicsContext& m_context;
-};
-
 static bool shouldCreateSubsequence(const PaintLayer& paintLayer, GraphicsContext& context, const PaintLayerPaintingInfo& paintingInfo, PaintLayerFlags paintFlags)
 {
     if (!RuntimeEnabledFeatures::paintOptimizationsEnabled())
@@ -317,7 +243,23 @@ PaintLayerPainter::PaintResult PaintLayerPainter::paintLayerContents(GraphicsCon
 
     // These helpers output clip and compositing operations using a RAII pattern. Stack-allocated-varibles are destructed in the reverse order of construction,
     // so they are nested properly.
-    ClipPathHelper clipPathHelper(context, m_paintLayer, paintingInfo, rootRelativeBounds, rootRelativeBoundsComputed, offsetFromRoot, paintFlags);
+    Optional<ClipPathClipper> clipPathClipper;
+    // Clip-path, like border radius, must not be applied to the contents of a composited-scrolling container.
+    // It must, however, still be applied to the mask layer, so that the compositor can properly mask the
+    // scrolling contents and scrollbars.
+    if (m_paintLayer.layoutObject()->hasClipPath() && (!m_paintLayer.needsCompositedScrolling() || (paintFlags & PaintLayerPaintingChildClippingMaskPhase))) {
+        if (!rootRelativeBoundsComputed) {
+            rootRelativeBounds = m_paintLayer.physicalBoundingBoxIncludingReflectionAndStackingChildren(offsetFromRoot);
+            rootRelativeBoundsComputed = true;
+        }
+        paintingInfo.ancestorHasClipPathClipping = true;
+        // When SVG applies the clip and the coordinate system is "userspace on use", we must explicitly pass in
+        // the layer offset to have the clip paint in the correct location. When the coordinate system is
+        // "object bounding box" the offset is already accounted for in the rootRelativeBounds.

[Stephen Chennney, 2016/08/22 16:02:58]

This comment belongs in the new location.

[fs, 2016/08/22 16:23:54]

Moved (w/ minor edits.)

+        FloatRect floatRootRelativeBounds(rootRelativeBounds);
+        clipPathClipper.emplace(
+            context, *m_paintLayer.layoutObject(), floatRootRelativeBounds, floatRootRelativeBounds, FloatPoint(offsetFromRoot));
+    }
 
     Optional<CompositingRecorder> compositingRecorder;
     // Blending operations must be performed only with the nearest ancestor stacking context.