Fix positioning of CSS reference clips in composited layers.

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

 // Copyright 2015 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/SVGClipPainter.h"
 
 #include "core/dom/ElementTraversal.h"
 #include "core/layout/svg/LayoutSVGResourceClipper.h"
 #include "core/layout/svg/SVGLayoutSupport.h"
 #include "core/layout/svg/SVGResources.h"
@@ skipping 15 matching lines @@
 public:
     SVGClipExpansionCycleHelper(LayoutSVGResourceClipper& clip) : m_clip(clip) { clip.beginClipExpansion(); }
     ~SVGClipExpansionCycleHelper() { m_clip.endClipExpansion(); }
 private:
     LayoutSVGResourceClipper& m_clip;
 };
 
 } // namespace
 
 bool SVGClipPainter::prepareEffect(const LayoutObject& target, const FloatRect& targetBoundingBox,
-    const FloatRect& paintInvalidationRect, GraphicsContext& context, ClipperState& clipperState)
+    const FloatRect& paintInvalidationRect, const FloatPoint& layerPositionOffset, GraphicsContext& context, ClipperState& clipperState)
 {
     ASSERT(clipperState == ClipperNotApplied);
     ASSERT_WITH_SECURITY_IMPLICATION(!m_clip.needsLayout());
 
     m_clip.clearInvalidationMask();
 
     if (paintInvalidationRect.isEmpty() || m_clip.hasCycle())
         return false;
 
     SVGClipExpansionCycleHelper inClipExpansionChange(m_clip);
 
     AffineTransform animatedLocalTransform = toSVGClipPathElement(m_clip.element())->calculateAnimatedLocalTransform();
     // When drawing a clip for non-SVG elements, the CTM does not include the zoom factor.
     // In this case, we need to apply the zoom scale explicitly - but only for clips with
     // userSpaceOnUse units (the zoom is accounted for objectBoundingBox-resolved lengths).
     if (!target.isSVG() && m_clip.clipPathUnits() == SVGUnitTypes::SVG_UNIT_TYPE_USERSPACEONUSE) {
         ASSERT(m_clip.style());
         animatedLocalTransform.scale(m_clip.style()->effectiveZoom());
     }
 
     // First, try to apply the clip as a clipPath.
     Path clipPath;
     if (m_clip.asPath(animatedLocalTransform, targetBoundingBox, clipPath)) {
+        AffineTransform positionTransform;
+        positionTransform.translate(layerPositionOffset.x(), layerPositionOffset.y());
+        clipPath.transform(positionTransform);
         clipperState = ClipperAppliedPath;
         context.getPaintController().createAndAppend<BeginClipPathDisplayItem>(target, clipPath);
         return true;
     }
 
     // Fall back to masking.
     clipperState = ClipperAppliedMask;
 
     // Begin compositing the clip mask.
     CompositingRecorder::beginCompositing(context, target, SkXfermode::kSrcOver_Mode, 1, &paintInvalidationRect);
     {
-        if (!drawClipAsMask(context, target, targetBoundingBox, paintInvalidationRect, animatedLocalTransform)) {
+        if (!drawClipAsMask(context, target, targetBoundingBox, paintInvalidationRect, animatedLocalTransform, layerPositionOffset)) {
             // End the clip mask's compositor.
             CompositingRecorder::endCompositing(context, target);
             return false;
         }
     }
 
     // Masked content layer start.
     CompositingRecorder::beginCompositing(context, target, SkXfermode::kSrcIn_Mode, 1, &paintInvalidationRect);
 
     return true;
@@ skipping 11 matching lines @@
         CompositingRecorder::endCompositing(context, target);
 
         // Transfer clip mask -> bg (SrcOver)
         CompositingRecorder::endCompositing(context, target);
         break;
     default:
         ASSERT_NOT_REACHED();
     }
 }
 
-bool SVGClipPainter::drawClipAsMask(GraphicsContext& context, const LayoutObject& layoutObject, const FloatRect& targetBoundingBox, const FloatRect& targetPaintInvalidationRect, const AffineTransform& localTransform)
+bool SVGClipPainter::drawClipAsMask(GraphicsContext& context, const LayoutObject& layoutObject, const FloatRect& targetBoundingBox,
+    const FloatRect& targetPaintInvalidationRect, const AffineTransform& localTransform, const FloatPoint& layerPositionOffset)
 {
     if (LayoutObjectDrawingRecorder::useCachedDrawingIfPossible(context, layoutObject, DisplayItem::SVGClip))
         return true;
 
     SkPictureBuilder maskPictureBuilder(targetPaintInvalidationRect, nullptr, &context);
     GraphicsContext& maskContext = maskPictureBuilder.context();
     {
         TransformRecorder recorder(maskContext, layoutObject, localTransform);
 
         // Create a clipPathClipper if this clipPath is clipped by another clipPath.
         SVGResources* resources = SVGResourcesCache::cachedResourcesForLayoutObject(&m_clip);
         LayoutSVGResourceClipper* clipPathClipper = resources ? resources->clipper() : nullptr;
         ClipperState clipPathClipperState = ClipperNotApplied;
-        if (clipPathClipper && !SVGClipPainter(*clipPathClipper).prepareEffect(m_clip, targetBoundingBox, targetPaintInvalidationRect, maskContext, clipPathClipperState))
+        if (clipPathClipper && !SVGClipPainter(*clipPathClipper).prepareEffect(m_clip, targetBoundingBox, targetPaintInvalidationRect, layerPositionOffset, maskContext, clipPathClipperState))
             return false;
 
         {
             AffineTransform contentTransform;
             if (m_clip.clipPathUnits() == SVGUnitTypes::SVG_UNIT_TYPE_OBJECTBOUNDINGBOX) {
                 contentTransform.translate(targetBoundingBox.x(), targetBoundingBox.y());
                 contentTransform.scaleNonUniform(targetBoundingBox.width(), targetBoundingBox.height());
             }
             SubtreeContentTransformScope contentTransformScope(contentTransform);
 
             TransformRecorder contentTransformRecorder(maskContext, layoutObject, contentTransform);
             RefPtr<const SkPicture> clipContentPicture = m_clip.createContentPicture();
             maskContext.getPaintController().createAndAppend<DrawingDisplayItem>(layoutObject, DisplayItem::SVGClip, clipContentPicture.get());
         }
 
         if (clipPathClipper)
             SVGClipPainter(*clipPathClipper).finishEffect(m_clip, maskContext, clipPathClipperState);
     }
 
     LayoutObjectDrawingRecorder drawingRecorder(context, layoutObject, DisplayItem::SVGClip, targetPaintInvalidationRect);
     RefPtr<SkPicture> maskPicture = maskPictureBuilder.endRecording();
     context.drawPicture(maskPicture.get());
     return true;
 }
 
 } // namespace blink