Correctly position abspos content inside relpos inlines [spv2]

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 122d51da837519544bd8f1ec9b499d41e5c6477b..5456808e938a3a40725aadc938927836fca49aa4 100644
--- a/third_party/WebKit/Source/core/paint/PaintPropertyTreeBuilder.cpp
+++ b/third_party/WebKit/Source/core/paint/PaintPropertyTreeBuilder.cpp
@@ -6,6 +6,7 @@
 
 #include "core/frame/FrameView.h"
 #include "core/frame/Settings.h"
+#include "core/layout/LayoutInline.h"
 #include "core/layout/LayoutPart.h"
 #include "core/paint/ObjectPaintProperties.h"
 #include "core/paint/PaintLayer.h"
@@ -333,6 +334,20 @@ void PaintPropertyTreeBuilder::updateOutOfFlowContext(LayoutObject& object, Pain
         context.transformForAbsolutePosition = context.currentTransform;
         context.paintOffsetForAbsolutePosition = context.paintOffset;
         context.clipForAbsolutePosition = context.currentClip;
+
+        // Absolutely positioned content in an inline should be positioned relative to the first
+        // inline box. See: LayoutInline::offsetForInFlowPositionedInline.
+        // FIXME(pdr): There is a special case when the descendant has static position where this
+        // offset should be removed and an offset based on the inline position should be used instead.
+        if (object.isInline() && object.isLayoutInline()) {
+            const LayoutInline& layoutInline = toLayoutInline(object);
+            if (layoutInline.firstLineBox()) {
+                LayoutPoint inlineOffset = layoutInline.firstLineBox()->topLeft();
+                if (!object.styleRef().isHorizontalWritingMode())
+                    inlineOffset = inlineOffset.transposedPoint();
+                context.paintOffsetForAbsolutePosition += inlineOffset;
+            }
+        }

[Xianzhu, 2016/05/26 18:02:27]

It's better to use the same algorithm as in PaintInvalidationState
(https://code.google.com/p/chromium/codesearch#chromium/src/third_party/WebKit...)
and LayoutBox::mapToVisualRectInAncestorSpace() about absolute-position under
relative inline.

Why do we need to care about statically-positioned absolute-position? Hasn't it
be already layouted at the proper place?

     }
 
     // TODO(pdr): Remove the !object.isLayoutView() condition when removing FrameView