Fix selection handles in vertical writing modes.

third_party/WebKit/Source/core/editing/RenderedPosition.cpp

Index: third_party/WebKit/Source/core/editing/RenderedPosition.cpp
diff --git a/third_party/WebKit/Source/core/editing/RenderedPosition.cpp b/third_party/WebKit/Source/core/editing/RenderedPosition.cpp
index 96e85c1bb18ee59afaeaafe8a885b277bac0e17d..0c15b4941411ccb80d066aa8da9c8c3022fb6b2b 100644
--- a/third_party/WebKit/Source/core/editing/RenderedPosition.cpp
+++ b/third_party/WebKit/Source/core/editing/RenderedPosition.cpp
@@ -235,7 +235,7 @@ IntRect RenderedPosition::absoluteRect(LayoutUnit* extraWidthToEndOfLine) const
     return localRect == IntRect() ? IntRect() : m_layoutObject->localToAbsoluteQuad(FloatRect(localRect)).enclosingBoundingBox();
 }
 
-void RenderedPosition::positionInGraphicsLayerBacking(CompositedSelectionBound& bound) const
+void RenderedPosition::positionInGraphicsLayerBacking(CompositedSelectionBound& bound, bool selectionStart) const
 {
     bound.layer = nullptr;
     bound.edgeTopInLayer = bound.edgeBottomInLayer = FloatPoint();
@@ -245,8 +245,27 @@ void RenderedPosition::positionInGraphicsLayerBacking(CompositedSelectionBound&
 
     LayoutRect rect = m_layoutObject->localCaretRect(m_inlineBox, m_offset);
     PaintLayer* layer = nullptr;
-    bound.edgeTopInLayer = m_layoutObject->localToInvalidationBackingPoint(rect.minXMinYCorner(), &layer);
-    bound.edgeBottomInLayer = m_layoutObject->localToInvalidationBackingPoint(rect.minXMaxYCorner(), nullptr);
+    bool vertical = m_layoutObject->hasFlippedBlocksWritingMode() || m_layoutObject->style()->isFlippedLinesWritingMode();

[kojii, 2015/12/16 17:30:58]

I think |!m_layoutObject->isHorizontalWritingMode()| is better here.

[aelias_OOO_until_Jul13, 2016/01/08 02:24:12]

Done.  Note that I needed to do
m_layoutObject->style()->isHorizontalWritingMode() instead, as the bit on
LayoutObject itself isn't updated properly (expected?).

[kojii, 2016/01/08 04:16:51]

It should have been set in LayoutBoxModelObject::updateFromStyle() which is
called from LayoutBoxModelObject::styleDidChange(), so it may happen if
m_layoutObject is non-box (inline etc.)

I think it's ok here, the purpose is to test horizontal/vertical rather than
flipped or not.

+    if (!vertical) {
+        bound.edgeTopInLayer = m_layoutObject->localToInvalidationBackingPoint(rect.minXMinYCorner(), &layer);
+        bound.edgeBottomInLayer = m_layoutObject->localToInvalidationBackingPoint(rect.minXMaxYCorner(), nullptr);
+    } else {
+        bound.edgeTopInLayer = m_layoutObject->localToInvalidationBackingPoint(rect.minXMinYCorner(), &layer);
+        bound.edgeBottomInLayer = m_layoutObject->localToInvalidationBackingPoint(rect.maxXMinYCorner(), nullptr);
+
+        // When text is vertical, it looks better for the start handle baseline to
+        // be at the starting edge, to enclose the selection fully between the
+        // handles.
+        if (selectionStart) {
+            float xSwap = bound.edgeBottomInLayer.x();
+            bound.edgeBottomInLayer.setX(bound.edgeTopInLayer.x());
+            bound.edgeTopInLayer.setX(xSwap);
+        }
+
+        // Flipped blocks writing mode is not only vertical but also right to left.
+        bound.isTextDirectionRTL = m_layoutObject->hasFlippedBlocksWritingMode();
+    }
+
     bound.layer = layer ? layer->graphicsLayerBacking() : nullptr;
 }