[SPv2] Respect transform-style in the Blink and cc property trees.

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/frame/LocalFrame.h"
 #include "core/frame/Settings.h"
 #include "core/layout/LayoutInline.h"
@@ skipping 101 matching lines @@
 
         // FIXME(pdr): Check for the presence of a transform instead of the value. Checking for an
         // identity matrix will cause the property tree structure to change during animations if
         // the animation passes through the identity matrix.
         // FIXME(pdr): Refactor this so all non-root SVG objects use the same transform function.
         const AffineTransform& transform = object.isSVGForeignObject() ? object.localSVGTransform() : object.localToSVGParentTransform();
         if (transform.isIdentity())
             return;
 
         // The origin is included in the local transform, so use an empty origin.
+        // TODO(jbroman, pdr): Handle flattening in SVG?

[trchen, 2016/07/13 04:39:44]

SVG doesn't support 3D transforms.

[jbroman, 2016/07/13 21:47:13]

Oh good; that simplifies things. I guess I should have realized that after
seeing AffineTransform above.

         RefPtr<TransformPaintPropertyNode> svgTransform = TransformPaintPropertyNode::create(
             transform, FloatPoint3D(0, 0, 0), context.currentTransform);
         context.currentTransform = svgTransform.get();
         object.getMutableForPainting().ensureObjectPaintProperties().setTransform(svgTransform.release());
         return;
     }
 
+    if (!object.isBox())
+        return;
     const ComputedStyle& style = object.styleRef();
-    if (!object.isBox() || !style.hasTransform())
+    if (!style.hasTransform() && !style.preserves3D())
         return;
 
     TransformationMatrix matrix;
     style.applyTransform(matrix, toLayoutBox(object).size(), ComputedStyle::ExcludeTransformOrigin,
         ComputedStyle::IncludeMotionPath, ComputedStyle::IncludeIndependentTransformProperties);
+
+    DCHECK(context.currentTransform);
+    const TransformPaintPropertyNode* renderingContextRoot =
+        context.currentTransform->preserves3D()
+        ? context.currentTransform->renderingContextRoot() : nullptr;
+
+    // These variables must be initialized to make MSVC happy.
+    TransformPaintPropertyNode::TransformStyle transformStyle =
+        TransformPaintPropertyNode::FlattenTransform;
+    TransformPaintPropertyNode::RenderingContextBehavior renderingContextBehavior =
+        TransformPaintPropertyNode::DontEstablishNewRenderingContext;
+    switch (style.transformStyle3D()) {
+    case TransformStyle3DFlat:

[chrishtr, 2016/07/13 20:30:50]

Given the requirement to initialize for MSVC, might as well just write:

if (style.transformStyle3D() == TransformStyle3DPreseve3D() {
  ...
}

+        transformStyle = TransformPaintPropertyNode::FlattenTransform;
+        break;
+    case TransformStyle3DPreserve3D:
+        transformStyle = TransformPaintPropertyNode::Preserve3D;
+        // If a node with transform-style: preserve-3d does not exist in an
+        // existing rendering context, it establishes a new one.
+        if (!renderingContextRoot)
+            renderingContextBehavior = TransformPaintPropertyNode::EstablishNewRenderingContext;
+        break;
+    }
+
     RefPtr<TransformPaintPropertyNode> transformNode = TransformPaintPropertyNode::create(
-        matrix, transformOrigin(toLayoutBox(object)), context.currentTransform);
+        matrix, transformOrigin(toLayoutBox(object)), context.currentTransform,
+        renderingContextBehavior, renderingContextRoot, transformStyle);
     context.currentTransform = transformNode.get();
     object.getMutableForPainting().ensureObjectPaintProperties().setTransform(transformNode.release());
 }
 
 void PaintPropertyTreeBuilder::updateEffect(const LayoutObject& object, PaintPropertyTreeBuilderContext& context)
 {
     if (!object.styleRef().hasOpacity())
         return;
     RefPtr<EffectPaintPropertyNode> effectNode = EffectPaintPropertyNode::create(object.styleRef().opacity(), context.currentEffect);
     context.currentEffect = effectNode.get();
@@ skipping 94 matching lines @@
         floatValueForLength(style.perspectiveOriginX(), borderBoxSize.width()),
         floatValueForLength(style.perspectiveOriginY(), borderBoxSize.height()));
 }
 
 void PaintPropertyTreeBuilder::updatePerspective(const LayoutObject& object, PaintPropertyTreeBuilderContext& context)
 {
     const ComputedStyle& style = object.styleRef();
     if (!object.isBox() || !style.hasPerspective())
         return;
 
+    // The perspective node must not flatten (else nothing will get
+    // perspective), but it should still extend the rendering context as most
+    // transform nodes do.
+    DCHECK(context.currentTransform);
     RefPtr<TransformPaintPropertyNode> perspective = TransformPaintPropertyNode::create(
         TransformationMatrix().applyPerspective(style.perspective()),
         perspectiveOrigin(toLayoutBox(object)) + toLayoutSize(context.paintOffset),
-        context.currentTransform);
+        context.currentTransform,
+        TransformPaintPropertyNode::DontEstablishNewRenderingContext,
+        context.currentTransform->renderingContextRoot(),
+        TransformPaintPropertyNode::Preserve3D);
     context.currentTransform = perspective.get();
     object.getMutableForPainting().ensureObjectPaintProperties().setPerspective(perspective.release());
 }
 
 void PaintPropertyTreeBuilder::updateSvgLocalToBorderBoxTransform(const LayoutObject& object, PaintPropertyTreeBuilderContext& context)
 {
     if (!object.isSVGRoot())
         return;
 
     AffineTransform transformToBorderBox = SVGRootPainter(toLayoutSVGRoot(object)).transformToPixelSnappedBorderBox(context.paintOffset);
@@ skipping 142 matching lines @@
     updateOverflowClip(object, context);
     // TODO(trchen): Insert flattening transform here, as specified by
     // http://www.w3.org/TR/css3-transforms/#transform-style-property
     updatePerspective(object, context);
     updateSvgLocalToBorderBoxTransform(object, context);
     updateScrollTranslation(object, context);
     updateOutOfFlowContext(object, context);
 }
 
 } // namespace blink