Repository navigation
fix: Prevent text layouting to break punctuation on adjacent spans - #4060
Merged
Merged
Conversation
luanpotter
marked this pull request as ready for review
September 27, 2026 15:47
spydon
approved these changes
Sep 28, 2026
spydon
left a comment
spydon
left a comment
Member
There was a problem hiding this comment.
Lgtm! Weren't we discussing before if we could just use Flutter's text layout pipeline instead of rolling our own?
4 of 5 tasks
spydon
added a commit
that referenced
this pull request
Oct 1, 2026
The rich text document pipeline (`DocumentRoot`, `ParagraphNode`, `HeaderNode`, and therefore `flame_markdown`) was the last place in Flame that broke lines itself. Its layout builder split on ASCII spaces, re-measured every tentative line with a fresh `TextPainter`, could not wrap CJK, threw on `TextAlign.justify`, lost kerning and ligatures at span boundaries, and needed glue heuristics for punctuation that were patched again in #4060 after #3192 and #3939. Since `InlineTextStyle` always renders through `TextPaint`, that pipeline can hand the whole block to Flutter's paragraph engine without losing any capability: - `InlineTextNode.layoutBuilder` is replaced by `InlineSpan toInlineSpan()`. `PlainTextNode` and `GroupTextNode` build a `TextSpan` tree, the wrapper nodes delegate to their child. - `TextBlockNode.format` lays out one `TextPainter` per block and returns the new `ParagraphTextElement`, which exposes `lines` and `lineMetrics`. Justify, CJK wrapping, hard line breaks, and shaping across differently styled spans now work. - `TextElement` gained a no-op `dispose()`, forwarded by `GroupElement`, which `ParagraphTextElement` uses to release its painter. - `TextBoxComponent` lays out a dedicated painter for wrapping and reads lines through `ParagraphTextElement`. It previously called `layout(maxWidth:)` on the painter shared through the `TextPaint` cache, so the wrapped layout leaked into later `format` calls for the same string. Per-line rendering, `align`, `growingBox` and the typewriter effect are unchanged. --------- Co-authored-by: Luan Nico <[email protected]>
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
Add this suggestion to a batch that can be applied as a single commit.This suggestion is invalid because no changes were made to the code.Suggestions cannot be applied while the pull request is closed.Suggestions cannot be applied while viewing a subset of changes.Only one suggestion per line can be applied in a batch.Add this suggestion to a batch that can be applied as a single commit.Applying suggestions on deleted lines is not supported.You must change the existing code in this line in order to create a valid suggestion.Outdated suggestions cannot be applied.This suggestion has been applied or marked resolved.Suggestions cannot be applied from pending reviews.Suggestions cannot be applied on multi-line comments.Suggestions cannot be applied while the pull request is queued to merge.Suggestion cannot be applied right now. Please check back later.
Description
Prevent text layouting to break punctuation on adjacent spans.
Currently any node gap is a potential break-point for line layouting; since a (for example)
**foo**.breaks into two nodes, the period might endup on the next line, which is a terrible layout decision.This changes the text layouting engine to look ahead to next groups if they are "glued" (no whitespace) to determine where to break the runs.
Note that this uses the existing line break rule, which only allows literal spaces (
.split(' ')on_PlainTextLayoutBuilder), which we can expand on a followup to comply to the unicode standard - that is completely tangential to this PR. Upgrading flame to re-use flutter's text layouting algo is also absolutely out of scope.Before:
After:
Checklist
docsand added dartdoc comments with///.examplesordocs.Breaking Change?
It is technically a minor breaking on the "inner workings" but exposed
TextNodeLayoutBuilderinterface that I doubt anyone uses, so not flagging to reduce noise on actual user-facing migration list; the fix is also simple, just add the two new overrides.