Fix bounding box propagation for <foreignObject>

Since the oBB is in unzoomed space but the <foreignObject>
local-to-parent transform performs adjustment for zoom we need to
perform correction when propagating it.
Similarly change LayoutSVGForeignObject::StrokeBoundingBox() to return
the same bounds as VisualRectInLocalSVGCoordinates() (which is zoomed).

Bug: 1162993
Change-Id: I430cd7832b37475ef1d139997ef5ac5c0bcc17c9
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2627491Reviewed-by: Philip Rogers <pdr@chromium.org>
Commit-Queue: Fredrik Söderquist <fs@opera.com>
Cr-Commit-Position: refs/heads/master@{#844016}

third_party/blink/renderer/core/layout/layout_object.h

@@ -1262,10 +1262,10 @@ class CORE_EXPORT LayoutObject : public ImageResourceObserver,
   // SVGGraphicsElement::getBBox().
   // NOTE: Markers are not specifically ignored here by SVG 1.1 spec, but we
   // ignore them since stroke-width is ignored (and marker size can depend on
-  // stroke-width). objectBoundingBox is returned local coordinates.
+  // stroke-width). objectBoundingBox is returned in local coordinates and
+  // always unzoomed.
   // The name objectBoundingBox is taken from the SVG 1.1 spec.
   virtual FloatRect ObjectBoundingBox() const;
-  virtual FloatRect StrokeBoundingBox() const;
 
   // Returns the smallest rectangle enclosing all of the painted content
   // respecting clipping, masking, filters, opacity, stroke-width and markers.
@@ -1275,6 +1275,11 @@ class CORE_EXPORT LayoutObject : public ImageResourceObserver,
   // coordinate space is the viewport space.
   virtual FloatRect VisualRectInLocalSVGCoordinates() const;
 
+  // Like VisualRectInLocalSVGCoordinates() but does not include visual overflow
+  // (name is misleading). May be zoomed (currently only for <foreignObject>,
+  // which represents this via its LocalToSVGParentTransform()).
+  virtual FloatRect StrokeBoundingBox() const;
+
   // This returns the transform applying to the local SVG coordinate space,
   // which combines the CSS transform properties and animation motion transform.
   // See SVGElement::calculateTransform().

third_party/blink/renderer/core/layout/svg/layout_svg_foreign_object.h

@@ -72,7 +72,7 @@ class LayoutSVGForeignObject final : public LayoutSVGBlock {
   }
   FloatRect StrokeBoundingBox() const override {
     NOT_DESTROYED();
-    return ObjectBoundingBox();
+    return VisualRectInLocalSVGCoordinates();
   }
   FloatRect VisualRectInLocalSVGCoordinates() const override {
     NOT_DESTROYED();

third_party/blink/renderer/core/layout/svg/layout_svg_foreign_object_test.cc

@@ -387,4 +387,25 @@ TEST_F(LayoutSVGForeignObjectTest, HitTestUnderScrollingAncestor) {
   EXPECT_EQ(PhysicalOffset(450, 450), result.PointInInnerNodeFrame());
 }
 
+TEST_F(LayoutSVGForeignObjectTest, BBoxPropagationZoomed) {
+  GetFrame().SetPageZoomFactor(2);
+  SetBodyInnerHTML(R"HTML(
+    <svg>
+      <g>
+        <foreignObject x="6" y="5" width="100" height="50" id="target"/>
+      </g>
+    </svg>
+  )HTML");
+  UpdateAllLifecyclePhasesForTest();
+
+  const auto& target = *GetLayoutObjectByElementId("target");
+  ASSERT_EQ(target.StyleRef().EffectiveZoom(), 2);
+
+  EXPECT_EQ(target.ObjectBoundingBox(), FloatRect(6, 5, 100, 50));
+  EXPECT_EQ(target.StrokeBoundingBox(), FloatRect(12, 10, 200, 100));
+  const auto& parent_g = *target.Parent();
+  EXPECT_EQ(parent_g.ObjectBoundingBox(), FloatRect(6, 5, 100, 50));
+  EXPECT_EQ(parent_g.StrokeBoundingBox(), FloatRect(6, 5, 100, 50));
+}
+
 }  // namespace blink

third_party/blink/renderer/core/layout/svg/svg_content_container.cc

@@ -143,6 +143,16 @@ static bool HasValidBoundingBoxForContainer(const LayoutObject& object) {
   return false;
 }
 
+static FloatRect ObjectBoundsForPropagation(const LayoutObject& object) {
+  FloatRect bounds = object.ObjectBoundingBox();
+  // The local-to-parent transform for <foreignObject> contains a zoom inverse,
+  // so we need to apply zoom to the bounding box that we use for propagation to
+  // be in the correct coordinate space.
+  if (IsA<LayoutSVGForeignObject>(object))
+    bounds.Scale(object.StyleRef().EffectiveZoom());
+  return bounds;
+}
+
 bool SVGContentContainer::UpdateBoundingBoxes(bool& object_bounding_box_valid) {
   object_bounding_box_valid = false;
 
@@ -154,8 +164,9 @@ bool SVGContentContainer::UpdateBoundingBoxes(bool& object_bounding_box_valid) {
     if (!HasValidBoundingBoxForContainer(*current))
       continue;
     const AffineTransform& transform = current->LocalToSVGParentTransform();
-    UpdateObjectBoundingBox(object_bounding_box, object_bounding_box_valid,
-                            transform.MapRect(current->ObjectBoundingBox()));
+    UpdateObjectBoundingBox(
+        object_bounding_box, object_bounding_box_valid,
+        transform.MapRect(ObjectBoundsForPropagation(*current)));
     stroke_bounding_box.Unite(transform.MapRect(current->StrokeBoundingBox()));
   }