prefer breaking lines at a zero width space. #8255
Conversation
Mapbox data sources use zero width spaces to suggest better break points for Japanese labels. This somewhat hacky approach avoids adding more complex line breaking logic to -gl-js.
|
@ansis I think I should port it to gl-native, right? |
A negative penalty on zero width spaces was not enough to prioritize them.
|
@lily-chai found that prioritizing zero width spaces couldn't effectively both break at zws and not break too often. Instead I've implemented penalization for ideographic breaks which seems to work better. @alexshalamov yes! |
src/symbol/shaping.js
Outdated
| calculatePenalty(codePoint, logicalInput.getCharCode(i + 1)), | ||
| false)); | ||
| if ((i < logicalInput.length() - 1)) { | ||
| const ideographicBreak = !breakable[codePoint] && charAllowsIdeographicBreaking(codePoint); |
There was a problem hiding this comment.
I dont see any overlap between charAllowsIdeographicBreakingand breakable codepoints. This check could be just charAllowsIdeographicBreaking;
| // Penalize breaks between characters that allow ideographic breaking because | ||
| // they are less preferable than breaks at spaces (or zero width spaces). | ||
| if (penalizableIdeographicBreak) { | ||
| penalty += 150; |
There was a problem hiding this comment.
From the rendering test failures, it looks like this change regresses the balanced line breaking in #3743. The penalty is probably too high.
| if (penalizableIdeographicBreak) { | ||
| penalty += 150; | ||
| } | ||
|
|
||
| // Penalize open parenthesis at end of line | ||
| if (codePoint === 0x28 || codePoint === 0xff08) { | ||
| penalty += 50; |
There was a problem hiding this comment.
The text-max-width/ideographic-punctuation-breaking test failure shows that this penalty is too low compared to the new penalty introduced above.
|
I've fixed the render tests by enabling the penalty only when a zws is present in the string. Capturing a conversation with @1ec5 from chat: This exception isn't great but shouldn't pose any problems if we change our approach in the future. |
Mapbox data sources use zero width spaces to suggest better break points for Japanese labels. This somewhat hacky approach avoids adding more complex line breaking logic to -gl-js.
@asheemmamoowala @lily-chai
Launch Checklist