Bug 112227 – REGRESSION (r133351, sub-pixel layout): Right-to-left block with text-overflow: ellipsis truncates prematurely (breaks facebook.com Hebrew UI)

• Component: Layout and Rendering
• Status: RESOLVED FIXED

To reproduce, navigate to the URL. The text truncated with ellipsis, even though it could fit untruncated (or the box could be made wider to let it fit). The same can be seen in many UI elements at facebook.com when the UI language is set to Hebrew on the website.

This was caused by <http://trac.webkit.org/r133351>.

[Radar WebKit Bug Importer]

<rdar://problem/13408101>

[Levi Weintraub]

Thanks for the great reduction!

[Simon Fraser (smfr)]

Levi: any update?

[Robert Hogan]

I can't reproduce with r144213.

[Allan Sandfeld Jensen]

I can't reproduce the issue either, using r149181 and Qt with subpixel-layout.

[zalan]

I can repro it on Mac with subpixel on. (r160307)

[zalan]

Truncation happens when right/left offsets are integral snapped (so available width is int snapped too) while the computed text length is not. When we try to fit the text, we start truncating because available width < text length. The fix is either snap both the available width and the text length or neither. Our approach is to not to snap during layout time, however removing just these 2 snappings introduce regression. I am going to address it when inlines are properly un-snapped. 

diff --git a/Source/WebCore/rendering/RenderBlockLineLayout.cpp b/Source/WebCore/rendering/RenderBlockLineLayout.cpp
index 112d972..56685d8 100644
--- a/Source/WebCore/rendering/RenderBlockLineLayout.cpp
+++ b/Source/WebCore/rendering/RenderBlockLineLayout.cpp
@@ -614,8 +614,8 @@ void RenderBlockFlow::updateLogicalWidthForAlignment(const ETextAlign& textAlign
 static void updateLogicalInlinePositions(RenderBlockFlow& block, float& lineLogicalLeft, float& lineLogicalRight, float& availableLogicalWidth, bool firstLine, IndentTextOrNot shouldIndentText, Layou
 {
     LayoutUnit lineLogicalHeight = block.minLineHeightForReplacedRenderer(firstLine, boxLogicalHeight);
-    lineLogicalLeft = block.pixelSnappedLogicalLeftOffsetForLine(block.logicalHeight(), shouldIndentText == IndentText, lineLogicalHeight);
-    lineLogicalRight = block.pixelSnappedLogicalRightOffsetForLine(block.logicalHeight(), shouldIndentText == IndentText, lineLogicalHeight);
+    lineLogicalLeft = block.logicalLeftOffsetForLine(block.logicalHeight(), shouldIndentText == IndentText, lineLogicalHeight);
+    lineLogicalRight = block.logicalRightOffsetForLine(block.logicalHeight(), shouldIndentText == IndentText, lineLogicalHeight);
     availableLogicalWidth = lineLogicalRight - lineLogicalLeft;
 }

[zalan]

Created attachment 231580 [details]
Patch

[Maciej Stachowiak]

Comment on attachment 231580 [details]
Patch

r=me

[WebKit Commit Bot]

Comment on attachment 231580 [details]
Patch

Clearing flags on attachment: 231580

Committed r169048: <http://trac.webkit.org/changeset/169048>

[WebKit Commit Bot]

All reviewed patches have been landed.  Closing bug.