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Chrome gives some invisible characters, such as a soft hyphen (U+00AD) or a zero width space (U+200B), no text cluster. Their code units were left mapped to cluster 0, so a text range that included one could map to a cluster range that went backwards. Laying out a paragraph that ends with one of these characters failed the assertion in _TextClusterMapping.toTextRange. Map each of those code units to the cluster before it, or to the first cluster at the start of the text. A cluster range that starts at such a code unit then starts at the next cluster, so a span that starts with one covers only its own clusters.
Draws a hyphen at the end of a line that breaks at a soft hyphen (U+00AD), unless ParagraphStyle.hyphens is Hyphens.hidden. This matches SkParagraph, which CanvasKit, Skwasm and the native engine use: * The hyphen is drawn only where the line breaks at the soft hyphen: not at the end of the text, before a space or newline, or on a line with an ellipsis. * A soft hyphen break only fits if the hyphen fits too. Otherwise the line breaks at the last earlier break that fits, or the hyphen overflows if there is none. * minIntrinsicWidth and longestLine include the hyphen; maxIntrinsicWidth and LineMetrics.width do not. * The hyphen takes the soft hyphen's style, is shaped in the direction of the text it ends, and goes at the end of the line in the paragraph's direction. * Selection boxes, glyph info and hit testing for the soft hyphen use the drawn hyphen. Fixes flutter#193506.
Add contract tests for clusterless characters (U+00AD, U+200B, U+200F) at paragraph and line starts, in standalone styled spans, and before newlines, as well as soft hyphens immediately after whitespace and upstream TextAffinity when hit-testing a drawn soft hyphen. Assisted-by: Gemini 4 Argon (Medium)
Fix five edge cases in cluster mapping, line layout, and soft-hyphen wrapping: 1. In _TextClusterMapping.toClusterRange, decrement endClusterIndex when _clusters[endClusterIndex - 1].start >= end so leading clusterless code units at offset 0 map to an empty ClusterRange(0, 0) instead of ClusterRange(0, 1). 2. In TextLayout.extractBidiRuns and TextLayout.addLine, skip empty clusterRange and bidiLineSpanRange slices produced by standalone clusterless characters (such as U+200F, U+00AD, or U+200B). 3. In TextLayout.addLine, start contentTextRange and allTextRange at 0 for the first line and at lines.last.hardLineBreakRange.end for subsequent lines so leading clusterless characters do not leave gaps in WebParagraph.getLineNumberAt. 4. In _LineBuilder.markSoftLineBreak and consumePendingText, ignore softHyphen when !hasPendingText so a soft hyphen immediately after whitespace breaks at the space without reserving hyphen width or inflating minIntrinsicWidth. 5. In TextLayout.getPositionForOffset, return TextAffinity.upstream when hit-testing a SoftHyphenBlock so line-boundary and closest-glyph queries stay on the hyphenated line. Without this fix, 9 tests in paragraph_edge_cases_test.dart and paragraph_soft_hyphen_test.dart fail (+73 -7 in felt test). Assisted-by: Gemini 3.8 Flash (router)
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…r#195384) Chrome gives some invisible characters, such as a soft hyphen (U+00AD), a zero width space (U+200B) or a right-to-left mark (U+200F), no text cluster. WebParagraph left their code units mapped to cluster 0, so a text range that includes one can map to the wrong clusters. On master: * Laying out a paragraph that ends with a soft hyphen or zero width space fails the assertion in `_TextClusterMapping.toTextRange`. * Laying out a paragraph whose only text is one of these characters throws a `StateError`. * Wrapping text where a space is followed by one of these characters, such as `'ab \u200F\u200Fcd'`, fails an assertion in `TextWrapper.breakLines`. * `getLineNumberAt` fails an assertion for a line that starts with one of these characters. * A right-to-left mark at the start of an LTR paragraph makes the first letter count twice in the line width. * A styled span that contains only one of these characters adds an empty box to `getBoxesForRange`. This maps each of those code units to the cluster before it, or to the first cluster at the start of the text, so a range that starts or ends at one of them does not take a cluster next to it. Bidi regions and span slices with no clusters add no bidi run and no block to the line, and a line's text range starts where the previous line ended and ends where the next line starts. A paragraph with no clusters is laid out like empty text, and the line breaker also finds a soft line break that lands on one of these characters. This was the first commit of flutter#195366 (soft hyphens in WebParagraph, for flutter#193506). @Rusino found three of these cases while reviewing that PR, wrote the fixes and tests in flutter#195377, and suggested landing this part on its own first. Her two commits from flutter#195386 add the rest: paragraphs with only these characters, and line breaks next to them. ## Testing `paragraph_edge_cases_test.dart` has a new group for these characters. Eleven of its tests fail on master. The two tests for a soft line break before a direction mark after a zero width space pass on master with Chrome 145 on my machine, so they may depend on the Chrome version. I ran the `chrome-dart2js-webparagraph-ui` suite locally on macOS with `felt test --gcs-prod`. Everything passes except "Paragraph with different locales for the same language" and "paint overflows" in `paragraph_test.dart`, which fail the same way on master on my machine. ## Pre-launch Checklist - [x] I read the [Contributor Guide] and followed the process outlined there for submitting PRs. - [x] I read the [AI contribution guidelines] and understand my responsibilities, or I am not using AI tools. - [x] I read the [Tree Hygiene] wiki page, which explains my responsibilities. - [x] I read and followed the [Flutter Style Guide], including [Features we expect every widget to implement]. - [x] I signed the [CLA]. - [ ] I listed at least one issue that this PR fixes in the description above. - [x] I updated/added relevant in-code documentation (doc comments with `///`). - [x] If this PR introduces a new feature or capability, I created and linked a website documentation issue or PR in [flutter/website] (or verified none is needed). - [x] I added new tests to check the change I am making, or this PR is [test-exempt]. - [x] I followed the [breaking change policy] and added [Data Driven Fixes] where supported. - [ ] All existing and new tests are passing. <!-- Links --> [Contributor Guide]: https://github.com/flutter/flutter/blob/main/docs/contributing/Tree-hygiene.md#overview [AI contribution guidelines]: https://github.com/flutter/flutter/blob/main/docs/contributing/Tree-hygiene.md#ai-contribution-guidelines [Tree Hygiene]: https://github.com/flutter/flutter/blob/main/docs/contributing/Tree-hygiene.md [test-exempt]: https://github.com/flutter/flutter/blob/main/docs/contributing/Tree-hygiene.md#tests [Flutter Style Guide]: https://github.com/flutter/flutter/blob/main/docs/contributing/Style-guide-for-Flutter-repo.md [Features we expect every widget to implement]: https://github.com/flutter/flutter/blob/main/docs/contributing/Style-guide-for-Flutter-repo.md#features-we-expect-every-widget-to-implement [CLA]: https://cla.developers.google.com/ [flutter/website]: https://github.com/flutter/website [breaking change policy]: https://github.com/flutter/flutter/blob/main/docs/contributing/Tree-hygiene.md#handling-breaking-changes [Data Driven Fixes]: https://github.com/flutter/flutter/blob/main/docs/contributing/Data-driven-Fixes.md --------- Co-authored-by: Julia Lavrova <[email protected]>
gmackall
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Nov 3, 2026
…r#195384) Chrome gives some invisible characters, such as a soft hyphen (U+00AD), a zero width space (U+200B) or a right-to-left mark (U+200F), no text cluster. WebParagraph left their code units mapped to cluster 0, so a text range that includes one can map to the wrong clusters. On master: * Laying out a paragraph that ends with a soft hyphen or zero width space fails the assertion in `_TextClusterMapping.toTextRange`. * Laying out a paragraph whose only text is one of these characters throws a `StateError`. * Wrapping text where a space is followed by one of these characters, such as `'ab \u200F\u200Fcd'`, fails an assertion in `TextWrapper.breakLines`. * `getLineNumberAt` fails an assertion for a line that starts with one of these characters. * A right-to-left mark at the start of an LTR paragraph makes the first letter count twice in the line width. * A styled span that contains only one of these characters adds an empty box to `getBoxesForRange`. This maps each of those code units to the cluster before it, or to the first cluster at the start of the text, so a range that starts or ends at one of them does not take a cluster next to it. Bidi regions and span slices with no clusters add no bidi run and no block to the line, and a line's text range starts where the previous line ended and ends where the next line starts. A paragraph with no clusters is laid out like empty text, and the line breaker also finds a soft line break that lands on one of these characters. This was the first commit of flutter#195366 (soft hyphens in WebParagraph, for flutter#193506). @Rusino found three of these cases while reviewing that PR, wrote the fixes and tests in flutter#195377, and suggested landing this part on its own first. Her two commits from flutter#195386 add the rest: paragraphs with only these characters, and line breaks next to them. ## Testing `paragraph_edge_cases_test.dart` has a new group for these characters. Eleven of its tests fail on master. The two tests for a soft line break before a direction mark after a zero width space pass on master with Chrome 145 on my machine, so they may depend on the Chrome version. I ran the `chrome-dart2js-webparagraph-ui` suite locally on macOS with `felt test --gcs-prod`. Everything passes except "Paragraph with different locales for the same language" and "paint overflows" in `paragraph_test.dart`, which fail the same way on master on my machine. ## Pre-launch Checklist - [x] I read the [Contributor Guide] and followed the process outlined there for submitting PRs. - [x] I read the [AI contribution guidelines] and understand my responsibilities, or I am not using AI tools. - [x] I read the [Tree Hygiene] wiki page, which explains my responsibilities. - [x] I read and followed the [Flutter Style Guide], including [Features we expect every widget to implement]. - [x] I signed the [CLA]. - [ ] I listed at least one issue that this PR fixes in the description above. - [x] I updated/added relevant in-code documentation (doc comments with `///`). - [x] If this PR introduces a new feature or capability, I created and linked a website documentation issue or PR in [flutter/website] (or verified none is needed). - [x] I added new tests to check the change I am making, or this PR is [test-exempt]. - [x] I followed the [breaking change policy] and added [Data Driven Fixes] where supported. - [ ] All existing and new tests are passing. <!-- Links --> [Contributor Guide]: https://github.com/flutter/flutter/blob/main/docs/contributing/Tree-hygiene.md#overview [AI contribution guidelines]: https://github.com/flutter/flutter/blob/main/docs/contributing/Tree-hygiene.md#ai-contribution-guidelines [Tree Hygiene]: https://github.com/flutter/flutter/blob/main/docs/contributing/Tree-hygiene.md [test-exempt]: https://github.com/flutter/flutter/blob/main/docs/contributing/Tree-hygiene.md#tests [Flutter Style Guide]: https://github.com/flutter/flutter/blob/main/docs/contributing/Style-guide-for-Flutter-repo.md [Features we expect every widget to implement]: https://github.com/flutter/flutter/blob/main/docs/contributing/Style-guide-for-Flutter-repo.md#features-we-expect-every-widget-to-implement [CLA]: https://cla.developers.google.com/ [flutter/website]: https://github.com/flutter/website [breaking change policy]: https://github.com/flutter/flutter/blob/main/docs/contributing/Tree-hygiene.md#handling-breaking-changes [Data Driven Fixes]: https://github.com/flutter/flutter/blob/main/docs/contributing/Data-driven-Fixes.md --------- Co-authored-by: Julia Lavrova <[email protected]>
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Companion draft PR stacked on top of #195366 (
8f0ff938c0b8337ccb5580e584526aa01c3773ab) by @dbebawy.Commit Structure (stacked on
8f0ff938c0b)e50f01a9c85) —[web_paragraph] Add failing soft hyphen tests:Adds 9 contract tests in
paragraph_edge_cases_test.dartandparagraph_soft_hyphen_test.dartthat fail on [web_paragraph] Render soft hyphens #195366 (+73 -7infelt test).269f171b2c4) —[web_paragraph] Fix soft hyphen edge cases:Fixes the 5 underlying edge cases in
layout.dartandwrapper.dart(all 80 tests in both files pass:+80 -0).Feel free to cherry-pick both commits, fold the changes into #195366, or take only the parts you want — I will close this draft PR once #195366 is updated.