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

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

Index: third_party/WebKit/Source/core/paint/PaintPropertyTreeBuilder.cpp
diff --git a/third_party/WebKit/Source/core/paint/PaintPropertyTreeBuilder.cpp b/third_party/WebKit/Source/core/paint/PaintPropertyTreeBuilder.cpp
index d0860a4a188193eaaaebbc0685d0f58a21805700..2af3cc968385df730db5275dc9507f20a76aea94 100644
--- a/third_party/WebKit/Source/core/paint/PaintPropertyTreeBuilder.cpp
+++ b/third_party/WebKit/Source/core/paint/PaintPropertyTreeBuilder.cpp
@@ -119,6 +119,7 @@ void PaintPropertyTreeBuilder::updateTransform(const LayoutObject& object, Paint
             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();
@@ -126,15 +127,42 @@ void PaintPropertyTreeBuilder::updateTransform(const LayoutObject& object, Paint
         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());
 }
@@ -249,10 +277,17 @@ void PaintPropertyTreeBuilder::updatePerspective(const LayoutObject& object, Pai
     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());
 }