Make 'transform' a presentation attribute on SVG elements

third_party/WebKit/Source/core/svg/SVGElement.cpp

Index: third_party/WebKit/Source/core/svg/SVGElement.cpp
diff --git a/third_party/WebKit/Source/core/svg/SVGElement.cpp b/third_party/WebKit/Source/core/svg/SVGElement.cpp
index 8a440b8d22faf05b063f0b0d7fa342a015b30cbe..0c4006def10c235c98ce2c56a20aeebb3f4d8bd4 100644
--- a/third_party/WebKit/Source/core/svg/SVGElement.cpp
+++ b/third_party/WebKit/Source/core/svg/SVGElement.cpp
@@ -312,6 +312,63 @@ AffineTransform SVGElement::localCoordinateSpaceTransform(CTMScope) const {
   return AffineTransform();
 }
 
+bool SVGElement::hasTransform() const {
+  return layoutObject() && layoutObject()->styleRef().hasTransform();
+}
+
+AffineTransform SVGElement::calculateTransform() const {
+  const ComputedStyle* style =
+      layoutObject() ? layoutObject()->style() : nullptr;
+
+  // If CSS property was set, use that, otherwise fallback to attribute (if
+  // set).
+  if (!style || !style->hasTransform())
+    return AffineTransform();
+
+  TransformationMatrix transform;
+  float zoom = style->effectiveZoom();
+
+  // SVGTextElements need special handling for the text positioning code.
+  if (isSVGTextElement(this)) {
+    // Do not take into account SVG's zoom rules, transform-origin, or
+    // percentage values.
+    style->applyTransform(transform, LayoutSize(0, 0),
+                          ComputedStyle::ExcludeTransformOrigin,
+                          ComputedStyle::IncludeMotionPath,
+                          ComputedStyle::IncludeIndependentTransformProperties);
+  } else {
+    // CSS transforms operate with pre-scaled lengths. To make this work with
+    // SVG (which applies the zoom factor globally, at the root level) we
+    //
+    //   * pre-scale the bounding box (to bring it into the same space as the
+    //     other CSS values)
+    //   * invert the zoom factor (to effectively compute the CSS transform
+    //     under a 1.0 zoom)
+    //
+    // Note: objectBoundingBox is an emptyRect for elements like pattern or
+    // clipPath.  See the "Object bounding box units" section of
+    // http://dev.w3.org/csswg/css3-transforms/
+    if (zoom != 1) {
+      FloatRect scaledBBox = layoutObject()->objectBoundingBox();
+      scaledBBox.scale(zoom);
+      transform.scale(1 / zoom);
+      style->applyTransform(
+          transform, scaledBBox, ComputedStyle::IncludeTransformOrigin,
+          ComputedStyle::IncludeMotionPath,
+          ComputedStyle::IncludeIndependentTransformProperties);
+      transform.scale(zoom);
+    } else {
+      style->applyTransform(
+          transform, layoutObject()->objectBoundingBox(),
+          ComputedStyle::IncludeTransformOrigin,
+          ComputedStyle::IncludeMotionPath,

[pdr., 2016/11/22 04:02:48]

Does this include motion path but exclude animate motion? Is that correct?

[fs, 2016/11/22 13:54:07]

Yes, correct. (SVGGraphicsElement::calculateAnimatedLocalTransform applies the
latter.)

+          ComputedStyle::IncludeIndependentTransformProperties);
+    }
+  }
+  // Flatten any 3D transform.
+  return transform.toAffineTransform();
+}
+
 Node::InsertionNotificationRequest SVGElement::insertedInto(
     ContainerNode* rootParent) {
   Element::insertedInto(rootParent);