Add a transform paint property for local SVG transforms

third_party/WebKit/Source/core/paint/PaintPropertyTreeBuilder.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/PaintPropertyTreeBuilder.h"
 
 #include "core/frame/FrameView.h"
 #include "core/layout/LayoutPart.h"
 #include "core/layout/LayoutView.h"
 #include "core/paint/ObjectPaintProperties.h"
@@ skipping 159 matching lines @@
     const ComputedStyle& style = box.styleRef();
     FloatSize borderBoxSize(box.size());
     return FloatPoint3D(
         floatValueForLength(style.transformOriginX(), borderBoxSize.width()),
         floatValueForLength(style.transformOriginY(), borderBoxSize.height()),
         style.transformOriginZ());
 }
 
 static PassRefPtr<TransformPaintPropertyNode> createTransformIfNeeded(const LayoutObject& object, PaintPropertyTreeBuilderContext& context)
 {
-    if (object.isSVG() && !object.isSVGRoot()) {
-        const AffineTransform& transform = object.localToSVGParentTransform();
-        if (transform.isIdentity())
-            return nullptr;
-
-        // SVG's transform origin is baked into the localToParentTransform.
-        RefPtr<TransformPaintPropertyNode> newTransformNodeForTransform = TransformPaintPropertyNode::create(
-            transform, FloatPoint3D(0, 0, 0), context.currentTransform);
-        context.currentTransform = newTransformNodeForTransform.get();
-        return newTransformNodeForTransform.release();
-    }
-
     const ComputedStyle& style = object.styleRef();
     if (!object.isBox() || !style.hasTransform())
         return nullptr;
 
     ASSERT(context.paintOffset == LayoutPoint());
 
     TransformationMatrix matrix;
     style.applyTransform(matrix, toLayoutBox(object).size(), ComputedStyle::ExcludeTransformOrigin,
         ComputedStyle::IncludeMotionPath, ComputedStyle::IncludeIndependentTransformProperties);
     RefPtr<TransformPaintPropertyNode> newTransformNodeForTransform = TransformPaintPropertyNode::create(
         matrix, transformOrigin(toLayoutBox(object)), context.currentTransform);
     context.currentTransform = newTransformNodeForTransform.get();
     return newTransformNodeForTransform.release();
 }
 
+static PassRefPtr<TransformPaintPropertyNode> createSvgLocalTransformIfNeeded(const LayoutObject& object, PaintPropertyTreeBuilderContext& context)
+{
+    if (!object.isSVG())
+        return nullptr;
+
+    const AffineTransform& transform = object.localToSVGParentTransform();
+    if (transform.isIdentity())
+        return nullptr;
+
+    // SVG's transform origin is baked into the localToSVGParentTransform so we use 0's for the origin.
+    RefPtr<TransformPaintPropertyNode> newTransformNodeForTransform = TransformPaintPropertyNode::create(
+        transform, FloatPoint3D(0, 0, 0), context.currentTransform);
+    context.currentTransform = newTransformNodeForTransform.get();
+    return newTransformNodeForTransform.release();
+}
+
 static PassRefPtr<EffectPaintPropertyNode> createEffectIfNeeded(const LayoutObject& object, PaintPropertyTreeBuilderContext& context)
 {
     const ComputedStyle& style = object.styleRef();
     if (!style.hasOpacity())
         return nullptr;
     RefPtr<EffectPaintPropertyNode> newEffectNode = EffectPaintPropertyNode::create(style.opacity(), context.currentEffect);
     context.currentEffect = newEffectNode.get();
     return newEffectNode.release();
 }
 
@@ skipping 107 matching lines @@
 
     RefPtr<TransformPaintPropertyNode> newTransformNodeForScrollTranslation = TransformPaintPropertyNode::create(
         TransformationMatrix().translate(-scrollOffset.width(), -scrollOffset.height()),
         FloatPoint3D(), context.currentTransform);
     context.currentTransform = newTransformNodeForScrollTranslation.get();
     return newTransformNodeForScrollTranslation.release();
 }
 
 static void updateOutOfFlowContext(const LayoutObject& object, PaintPropertyTreeBuilderContext& context, ClipPaintPropertyNode* newClipNodeForCSSClip, RefPtr<ClipPaintPropertyNode>& newClipNodeForCSSClipFixedPosition)
 {
+    // TODO(pdr): Always create an SVG transform for the root and remove this paint offset quirk.
     // At the html->svg boundary (see: createPaintOffsetTranslationIfNeeded) the currentTransform is
     // up-to-date for all children of the svg root element. Additionally, inside SVG, all positioning
     // uses transforms. Therefore, we only need to check createdNewTransform and isSVGRoot() to
     // ensure out-of-flow and fixed positioning is correct at the svg->html boundary.
 
     if (object.canContainAbsolutePositionObjects()) {
         context.transformForAbsolutePosition = context.currentTransform;
         context.paintOffsetForAbsolutePosition = context.paintOffset;
         context.clipForAbsolutePosition = context.currentClip;
     }
@@ skipping 49 matching lines @@
     RefPtr<TransformPaintPropertyNode> newTransformNodeForPaintOffsetTranslation = createPaintOffsetTranslationIfNeeded(object, localContext);
     RefPtr<TransformPaintPropertyNode> newTransformNodeForTransform = createTransformIfNeeded(object, localContext);
     RefPtr<EffectPaintPropertyNode> newEffectNode = createEffectIfNeeded(object, localContext);
     RefPtr<ClipPaintPropertyNode> newClipNodeForCSSClip = createCSSClipIfNeeded(object, localContext);
     OwnPtr<ObjectPaintProperties::LocalBorderBoxProperties> newRecordedContext = recordTreeContextIfNeeded(object, localContext);
     RefPtr<TransformPaintPropertyNode> newTransformNodeForScrollbarPaintOffset = createScrollbarPaintOffsetIfNeeded(object, localContext);
     RefPtr<ClipPaintPropertyNode> newClipNodeForOverflowClip = createOverflowClipIfNeeded(object, localContext);
     // TODO(trchen): Insert flattening transform here, as specified by
     // http://www.w3.org/TR/css3-transforms/#transform-style-property
     RefPtr<TransformPaintPropertyNode> newTransformNodeForPerspective = createPerspectiveIfNeeded(object, localContext);
+    RefPtr<TransformPaintPropertyNode> newTransformNodeForSvgLocalTransform = createSvgLocalTransformIfNeeded(object, localContext);
     RefPtr<TransformPaintPropertyNode> newTransformNodeForScrollTranslation = createScrollTranslationIfNeeded(object, localContext);
     RefPtr<ClipPaintPropertyNode> newClipNodeForCSSClipFixedPosition;
     updateOutOfFlowContext(object, localContext, newClipNodeForCSSClip.get(), newClipNodeForCSSClipFixedPosition);
 
-    if (newTransformNodeForPaintOffsetTranslation || newTransformNodeForTransform || newEffectNode || newClipNodeForCSSClip || newClipNodeForCSSClipFixedPosition || newClipNodeForOverflowClip || newTransformNodeForPerspective || newTransformNodeForScrollTranslation || newTransformNodeForScrollbarPaintOffset || newRecordedContext) {
+    DCHECK(!newTransformNodeForSvgLocalTransform || !newTransformNodeForScrollTranslation)
+        << "SVG elements cannot have scroll translation";
+
+    // TODO(pdr): Refactor this to use a less massive if statement.
+    if (newTransformNodeForPaintOffsetTranslation || newTransformNodeForTransform || newEffectNode || newClipNodeForCSSClip || newClipNodeForCSSClipFixedPosition || newClipNodeForOverflowClip || newTransformNodeForPerspective || newTransformNodeForSvgLocalTransform || newTransformNodeForScrollTranslation || newTransformNodeForScrollbarPaintOffset || newRecordedContext) {
         OwnPtr<ObjectPaintProperties> updatedPaintProperties = ObjectPaintProperties::create(
             newTransformNodeForPaintOffsetTranslation.release(),
             newTransformNodeForTransform.release(),
             newEffectNode.release(),
             newClipNodeForCSSClip.release(),
             newClipNodeForCSSClipFixedPosition.release(),
             newClipNodeForOverflowClip.release(),
             newTransformNodeForPerspective.release(),
+            newTransformNodeForSvgLocalTransform.release(),
             newTransformNodeForScrollTranslation.release(),
             newTransformNodeForScrollbarPaintOffset.release(),
             newRecordedContext.release());
         object.setObjectPaintProperties(updatedPaintProperties.release());
     } else {
         object.clearObjectPaintProperties();
     }
 
     for (LayoutObject* child = object.slowFirstChild(); child; child = child->nextSibling()) {
         if (child->isBoxModelObject() || child->isSVG())
             walk(*child, localContext);
     }
 
     if (object.isLayoutPart()) {
         Widget* widget = toLayoutPart(object).widget();
         if (widget && widget->isFrameView())
             walk(*toFrameView(widget), localContext);
         // TODO(pdr): Investigate RemoteFrameView (crbug.com/579281).
     }
 }
 
 } // namespace blink