[S.P.] Move clip painting to SVGClipPainter.

Source/core/paint/SVGClipPainter.cpp

Index: Source/core/paint/SVGClipPainter.cpp
diff --git a/Source/core/paint/SVGClipPainter.cpp b/Source/core/paint/SVGClipPainter.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..7e65202fb210ebc989bf5e899bd442e097096fc4
--- /dev/null
+++ b/Source/core/paint/SVGClipPainter.cpp
@@ -0,0 +1,140 @@
+// 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 "config.h"
+#include "core/paint/SVGClipPainter.h"
+
+#include "core/dom/ElementTraversal.h"
+#include "core/layout/PaintInfo.h"
+#include "core/layout/svg/LayoutSVGResourceClipper.h"
+#include "core/layout/svg/SVGResources.h"
+#include "core/layout/svg/SVGResourcesCache.h"
+#include "core/paint/CompositingRecorder.h"
+#include "core/paint/TransformRecorder.h"
+#include "platform/graphics/paint/ClipPathDisplayItem.h"
+#include "platform/graphics/paint/CompositingDisplayItem.h"
+#include "platform/graphics/paint/DisplayItemList.h"
+#include "platform/graphics/paint/DrawingDisplayItem.h"
+#include "wtf/TemporaryChange.h"
+
+namespace blink {
+
+bool SVGClipPainter::applyStatefulResource(LayoutObject* object, GraphicsContext* context, ClipperState& clipperState)
+{
+    ASSERT(object);
+    ASSERT(context);
+
+    m_clip.clearInvalidationMask();
+
+    return applyClippingToContext(object, object->objectBoundingBox(), object->paintInvalidationRectInLocalCoordinates(), context, clipperState);
+}
+
+class SVGClipExpansionCycleHelper {
+public:
+    SVGClipExpansionCycleHelper(LayoutSVGResourceClipper& clip) : m_clip(clip) { clip.beginClipExpansion(); }
+    ~SVGClipExpansionCycleHelper() { m_clip.endClipExpansion(); }
+private:
+    LayoutSVGResourceClipper& m_clip;
+};
+
+bool SVGClipPainter::applyClippingToContext(LayoutObject* target, const FloatRect& targetBoundingBox,
+    const FloatRect& paintInvalidationRect, GraphicsContext* context, ClipperState& clipperState)
+{
+    ASSERT(target);
+    ASSERT(context);
+    ASSERT(clipperState == ClipperNotApplied);
+    ASSERT_WITH_SECURITY_IMPLICATION(!m_clip.needsLayout());
+
+    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.
+    if (m_clip.tryPathOnlyClipping(target->displayItemClient(), context, animatedLocalTransform, targetBoundingBox)) {
+        clipperState = ClipperAppliedPath;
+        return true;
+    }
+
+    // Fall back to masking.
+    clipperState = ClipperAppliedMask;
+
+    // Begin compositing the clip mask.
+    CompositingRecorder::beginCompositing(context, target->displayItemClient(), SkXfermode::kSrcOver_Mode, 1, &paintInvalidationRect);
+    {
+        TransformRecorder recorder(*context, target->displayItemClient(), animatedLocalTransform);
+
+        // clipPath can also be clipped by another clipPath.
+        SVGResources* resources = SVGResourcesCache::cachedResourcesForLayoutObject(&m_clip);
+        LayoutSVGResourceClipper* clipPathClipper = resources ? resources->clipper() : 0;
+        ClipperState clipPathClipperState = ClipperNotApplied;
+        if (clipPathClipper && !SVGClipPainter(*clipPathClipper).applyClippingToContext(&m_clip, targetBoundingBox, paintInvalidationRect, context, clipPathClipperState)) {
+            // End the clip mask's compositor.
+            CompositingRecorder::endCompositing(context, target->displayItemClient());
+            return false;
+        }
+
+        drawClipMaskContent(context, target->displayItemClient(), targetBoundingBox);
+
+        if (clipPathClipper)
+            SVGClipPainter(*clipPathClipper).postApplyStatefulResource(&m_clip, context, clipPathClipperState);
+    }
+
+    // Masked content layer start.
+    CompositingRecorder::beginCompositing(context, target->displayItemClient(), SkXfermode::kSrcIn_Mode, 1, &paintInvalidationRect);
+
+    return true;
+}
+
+void SVGClipPainter::postApplyStatefulResource(LayoutObject* target, GraphicsContext* context, ClipperState& clipperState)
+{
+    switch (clipperState) {
+    case ClipperAppliedPath:
+        // Path-only clipping, no layers to restore but we need to emit an end to the clip path display item.
+        if (RuntimeEnabledFeatures::slimmingPaintEnabled()) {
+            context->displayItemList()->add(EndClipPathDisplayItem::create(target->displayItemClient()));
+        } else {
+            EndClipPathDisplayItem endClipPathDisplayItem(target->displayItemClient());
+            endClipPathDisplayItem.replay(context);
+        }
+        break;
+    case ClipperAppliedMask:
+        // Transfer content -> clip mask (SrcIn)
+        CompositingRecorder::endCompositing(context, target->displayItemClient());
+
+        // Transfer clip mask -> bg (SrcOver)
+        CompositingRecorder::endCompositing(context, target->displayItemClient());
+        break;
+    default:
+        ASSERT_NOT_REACHED();
+    }
+}
+
+void SVGClipPainter::drawClipMaskContent(GraphicsContext* context, DisplayItemClient client, const FloatRect& targetBoundingBox)
+{
+    ASSERT(context);
+
+    AffineTransform contentTransformation;
+    RefPtr<const SkPicture> clipContentPicture = m_clip.createContentPicture(contentTransformation, targetBoundingBox);
+
+    TransformRecorder recorder(*context, client, contentTransformation);
+    if (RuntimeEnabledFeatures::slimmingPaintEnabled()) {
+        ASSERT(context->displayItemList());
+        context->displayItemList()->add(DrawingDisplayItem::create(client, DisplayItem::SVGClip, clipContentPicture));
+    } else {
+        DrawingDisplayItem clipPicture(client, DisplayItem::SVGClip, clipContentPicture);
+        clipPicture.replay(context);
+    }
+}
+
+}