Apply container offset and scroll between transform and container perspective.

third_party/WebKit/Source/core/layout/VisualRectMappingTest.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/layout/LayoutTestHelper.h"
 #include "core/layout/LayoutView.h"
 #include "core/layout/PaintInvalidationState.h"
 #include "core/paint/PaintLayer.h"
 #include "core/paint/PaintPropertyTreePrinter.h"
 #include "platform/graphics/paint/GeometryMapper.h"
@@ skipping 17 matching lines @@
         object.ContainerForPaintInvalidation();
 
     CheckVisualRect(object, paint_invalidation_container, rect,
                     object.VisualRect(), true);
   }
 
   void CheckVisualRect(const LayoutObject& object,
                        const LayoutBoxModelObject& ancestor,
                        const LayoutRect& local_rect,
                        const LayoutRect& expected_visual_rect,
-                       bool adjust_for_backing = false) {
+                       bool adjust_for_backing = false,
+                       bool allow_empty_cache_slot = true) {
     LayoutRect slow_map_rect = local_rect;
     object.MapToVisualRectInAncestorSpace(&ancestor, slow_map_rect);
-    if (slow_map_rect.IsEmpty() && object.VisualRect().IsEmpty())
+    if (allow_empty_cache_slot && slow_map_rect.IsEmpty() &&
+        object.VisualRect().IsEmpty())
       return;
 
     FloatClipRect geometry_mapper_rect((FloatRect(local_rect)));
     if (object.PaintProperties() || object.LocalBorderBoxProperties()) {
       geometry_mapper_rect.MoveBy(FloatPoint(object.PaintOffset()));
       GeometryMapper::SourceToDestinationVisualRect(
           *object.LocalBorderBoxProperties(), *ancestor.ContentsProperties(),
           geometry_mapper_rect);
       geometry_mapper_rect.MoveBy(-FloatPoint(ancestor.PaintOffset()));
     }
@@ skipping 776 matching lines @@
   TransformationMatrix target_matrix;
   // getTransformfromContainter includes transform and perspective matrix
   // of the container.
   target->GetTransformFromContainer(container, LayoutSize(), target_matrix);
   matrix *= target_matrix;
   LayoutRect output(matrix.MapRect(FloatRect(original_rect)));
 
   CheckVisualRect(*target, *target->View(), original_rect, output);
 }
 
+TEST_F(VisualRectMappingTest, PerspectivePlusScroll) {
+  EnableCompositing();
+  SetBodyInnerHTML(
+      "<style>"
+      "* { margin: 0; }"
+      "#container {"
+      "  perspective: 100px;"
+      "  width: 100px; height: 100px;"
+      "  overflow: scroll;"
+      "}"
+      "#target {"
+      "  transform: rotatex(45eg);"
+      "  background: lightblue;"
+      "  width: 100px; height: 100px;"
+      "}"
+      "#spacer {"
+      "  width: 10px; height:2000px;"
+      "}"
+      "</style>"
+      "<div id='container'>"
+      "  <div id='target'></div>"
+      "  <div id='spacer'></div>"
+      "</div>");
+  LayoutBlock* container =
+      ToLayoutBlock(GetLayoutObjectByElementId("container"));
+  ToElement(container->GetNode())->scrollTo(0, 5);
+  GetDocument().View()->UpdateAllLifecyclePhases();
+
+  LayoutBlock* target = ToLayoutBlock(GetLayoutObjectByElementId("target"));
+  LayoutRect originalRect(0, 0, 100, 100);
+  TransformationMatrix transform;
+  target->GetTransformFromContainer(
+      container, target->OffsetFromContainer(container), transform);
+  transform.FlattenTo2d();
+
+  LayoutRect output(transform.MapRect(FloatRect(originalRect)));
+  output.Intersect(container->ClippingRect());
+  CheckVisualRect(*target, *target->View(), originalRect, output, false, false);
+}
+
 }  // namespace blink