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fix: Fix text rendering issue where spaces are missing - #3192
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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]>
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Description
Fix text rendering issue where spaces end up missing.
What happens is that if a single paragraph is split into multiple spans, due to having different formatting, for example, the layouting engine will run into an edge case when trying to place the last span. It will:
That is not normally an issue because if it doesn't fit, it will go to the next line and the space becomes unnecessary in that case. But in case we are still trying to populate the same line, we need to make sure we don't "eat up" the space.
There could be other similar edge cases where a space could go missing, so I opted to make it explicit whether the initial space should be added or not by adding a parameter to determine if it is the start of a new line or not.
Examples
Before:
After:
Checklist
docsand added dartdoc comments with///.examplesordocs.Breaking Change?