Fix wrong box-shadow visual overflow with flipped blocks writing mode

third_party/WebKit/Source/core/layout/LayoutObjectTest.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/LayoutObject.h"
 
 #include "core/layout/LayoutTestHelper.h"
 #include "core/layout/LayoutView.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
@@ skipping 185 matching lines @@
 
     LayoutBlock* frameContainer = toLayoutBlock(getLayoutObjectByElementId("frameContainer"));
     LayoutObject* target = frameDocument.getElementById("target")->layoutObject();
     LayoutRect rect(0, 0, 100, 100);
     EXPECT_TRUE(target->mapToVisualRectInAncestorSpace(frameContainer, rect));
     // When passing from the iframe to the parent frame, the rect of (0.5, 0, 100, 100) is expanded to (0, 0, 100, 100), and then offset by
     // the 0.5 offset of frameContainer.
     EXPECT_EQ(LayoutRect(LayoutPoint(DoublePoint(0.5, 0)), LayoutSize(101, 100)), rect);
 }
 
+TEST_F(LayoutObjectTest, OverflowRectMappingWithSelfFlippedWritingMode)
+{
+    setBodyInnerHTML(
+        "<div id='target' style='writing-mode: vertical-rl; box-shadow: 40px 20px black;"
+        "    width: 100px; height: 50px; position: absolute; top: 111px; left: 222px'>"
+        "</div>");
+
+    LayoutBlock* target = toLayoutBlock(getLayoutObjectByElementId("target"));
+    LayoutRect overflowRect = target->localOverflowRectForPaintInvalidation();
+    EXPECT_EQ(LayoutRect(-40, 0, 140, 70), overflowRect);
+    LayoutRect rect = overflowRect;
+    EXPECT_TRUE(target->mapToVisualRectInAncestorSpace(target, rect));
+    EXPECT_EQ(LayoutRect(0, 0, 140, 70), rect);
+    rect = overflowRect;
+    EXPECT_TRUE(target->mapToVisualRectInAncestorSpace(&layoutView(), rect));
+    EXPECT_EQ(LayoutRect(222, 111, 140, 70), rect);

[chrishtr, 2016/04/01 00:42:09]

Why is it offset by 222, 111? Isn't that the size of the view?

[Xianzhu, 2016/04/01 01:17:22]

They are absolute position of 'target' ("position absolute; top: 111px; left:
222px"). Using special numbers to make it obvious in the result and avoid
accidental correct result when the algorithm were wrong.

[chrishtr, 2016/04/01 16:50:58]

Oh right sorry.

+}
+
+TEST_F(LayoutObjectTest, OverflowRectMappingWithContainerFlippedWritingMode)
+{
+    setBodyInnerHTML(
+        "<div id='container' style='writing-mode: vertical-rl; position: absolute; top: 111px; left: 222px'>"
+        "    <div id='target' style='box-shadow: 40px 20px black; width: 100px; height: 90px'></div>"
+        "    <div style='width: 100px; height: 100px'></div>"
+        "</div>");
+
+    LayoutBlock* target = toLayoutBlock(getLayoutObjectByElementId("target"));
+    LayoutRect targetOverflowRect = target->localOverflowRectForPaintInvalidation();
+    EXPECT_EQ(LayoutRect(-40, 0, 140, 110), targetOverflowRect);
+    LayoutRect rect = targetOverflowRect;
+    EXPECT_TRUE(target->mapToVisualRectInAncestorSpace(target, rect));
+    EXPECT_EQ(LayoutRect(0, 0, 140, 110), rect);
+
+    LayoutBlock* container = toLayoutBlock(getLayoutObjectByElementId("container"));
+    rect = targetOverflowRect;
+    EXPECT_TRUE(target->mapToVisualRectInAncestorSpace(container, rect));
+    EXPECT_EQ(LayoutRect(100, 0, 140, 110), rect);
+    rect = targetOverflowRect;
+    EXPECT_TRUE(target->mapToVisualRectInAncestorSpace(&layoutView(), rect));
+    EXPECT_EQ(LayoutRect(322, 111, 140, 110), rect);
+
+    LayoutRect containerOverflowRect = container->localOverflowRectForPaintInvalidation();
+    EXPECT_EQ(LayoutRect(-40, 0, 240, 110), containerOverflowRect);
+    rect = containerOverflowRect;
+    EXPECT_TRUE(target->mapToVisualRectInAncestorSpace(container, rect));
+    EXPECT_EQ(LayoutRect(0, 0, 240, 110), rect);
+    rect = containerOverflowRect;
+    EXPECT_TRUE(target->mapToVisualRectInAncestorSpace(&layoutView(), rect));
+    EXPECT_EQ(LayoutRect(222, 111, 240, 110), rect);
+}
+
 } // namespace blink