752455 - text-transform disrupts cluster support in word-break:break-all

Status: RESOLVED FIXED

(Core :: Layout: Text and Fonts, defect)

Description

[Jonathan Kew [:jfkthame]]

With the patches currently in bug 249159 to implement the word-break property, there's an unwanted interaction with text-transform.

Comparing these two examples,

  data:text/html;charset=utf-8,
    <div style="width:0px;word-break:break-all">
    foob%CC%A5ar

  data:text/html;charset=utf-8,
    <div style="text-transform:lowercase;width:0px;word-break:break-all">
    foob%CC%A5ar

the results should be identical (the 'b' and combining ring below should remain together as a cluster), but the version with text-transform:lowercase incorrectly splits this onto separate lines.

Comment 1

[Jonathan Kew [:jfkthame]]

Attachment: patch, don't allow word break within cluster when copying glyph data for text-transform

The problem here arises because we set word-break positions on the destination textrun's characterGlyph array before we've done the RebuildTextRun for text-transform, but at that point it had no cluster information and so gfxTextRun::SetPotentialLineBreaks didn't suppress those breaks.

CopyGlyphDataFrom has the cluster data available in its source run, so it needs to remove any potential breaks in the destination that turn out to be inside clusters.

Comment 2

[Jonathan Kew [:jfkthame]]

Attachment: reftest for word-break, clusters, text-transform

Comment 3

[Jonathan Kew [:jfkthame]]

https://hg.mozilla.org/integration/mozilla-inbound/rev/32837f32c4b6
https://hg.mozilla.org/integration/mozilla-inbound/rev/141e694667c7

Comment 4

[Ryan VanderMeulen [:RyanVM]]

https://hg.mozilla.org/mozilla-central/rev/32837f32c4b6
https://hg.mozilla.org/mozilla-central/rev/141e694667c7