Bug 138891

Summary: [OS X] Upright vertical text is completely broken for multi-code-unit code points
Product: WebKit Reporter: Myles C. Maxfield <mmaxfield>
Component: New BugsAssignee: Myles C. Maxfield <mmaxfield>
Status: RESOLVED FIXED    
Severity: Normal CC: dino, jonlee, mitz, simon.fraser, thorton, webkit-bug-importer
Priority: P2 Keywords: InRadar
Version: 528+ (Nightly build)   
Hardware: Unspecified   
OS: Unspecified   
Bug Depends on:    
Bug Blocks: 144303    
Attachments:
Description Flags
Patch
none
Patch mitz: review+

Description Myles C. Maxfield 2014-11-19 15:30:45 PST
Upright vertical text is completely broken for multi-code-unit codepoints
Comment 1 Myles C. Maxfield 2014-11-19 15:49:01 PST
Created attachment 241899 [details]
Patch
Comment 2 Myles C. Maxfield 2014-11-19 15:49:32 PST
<rdar://problem/18421386>
Comment 3 mitz 2014-11-19 16:07:47 PST
Comment on attachment 241899 [details]
Patch

View in context: https://bugs.webkit.org/attachment.cgi?id=241899&action=review

> Source/WebCore/platform/graphics/mac/GlyphPageTreeNodeMac.cpp:153
> -                            setGlyphDataForIndex(offset + stringIndices[i], glyphs[i], fontData);
> +                            // Because of the size of the GlyphPage, the string will never straddle a code-unit size boundary
> +                            unsigned index = U16_IS_LEAD(buffer[stringIndices[i]]) ? stringIndices[i] / 2 : stringIndices[i];
> +                            setGlyphDataForIndex(offset + index, glyphs[i], fontData);

Shouldn’t you make this change in the else block below as well?

It’s weird to write the logic this way, because we are relying on the fact that buffer is either uniformly BMP characters or surrogate pairs. It wouldn’t work otherwise.

I think that instead you should use the glyphStep approach we use above.
Comment 4 Myles C. Maxfield 2014-11-19 16:26:08 PST
Created attachment 241905 [details]
Patch
Comment 5 Myles C. Maxfield 2014-11-19 17:35:47 PST
http://trac.webkit.org/changeset/176372