release: 1.13.0 — character-range highlight geometry (#26) + line-breaking fixes by vietnguyentuan2019 · Pull Request #27 · brewkits/hyper_render

vietnguyentuan2019 · 2026-10-08T06:33:09Z

Release 1.13.0 of hyper_render_core and hyper_render. Not published yet.

Eliminates the O(N²) line-breaking bottleneck on massive unspaced text: a 14,000-character CJK paragraph no longer takes ~13 s. On my machine 16,000 unspaced characters went from 4.7 s (CJK) / 1.9 s (Latin) to ~0.07 s / ~0.05 s.
Also fixes text-overflow: ellipsis on the first block of a document (it wrapped instead of truncating).
Follow-up on this branch: a floated block's unmeasured text was being measured, adding a phantom 8px line height (flagship_execution_audit_test). Narrowed the re-measure condition and added regression tests.
Behavior change: CJK text now fills the line after a space between runs, as a browser does. cjk_kinsoku.png golden regenerated.

Line-breaking fixes (found while reviewing #29; rendering changes)

Wrapped lines no longer overflow the box: the break point came from the nearest caret, so a line could run up to half a glyph past the edge. Every full CJK line did.
RTL paragraphs wrap. The breaker read an RTL painter from its logical end, so an Arabic paragraph put most of its text on line one and then one glyph per line.
word-break / overflow-wrap are inherited, so word-break: break-all on a  now reaches its text. It had no effect before.
A word wider than the line breaks after as many characters as fit, instead of after its first letter.
A word that doesn't fit beside a float moves below it, instead of being split as "c" / "onsectetur".
Spaces at the start and end of a line collapse (CSS Text 3 §4.1.2). Lines after   or an indented tag no longer start one space in, and centered / right-aligned lines ignore trailing spaces.

Goldens

15 goldens were regenerated on CI (Update Goldens (manual), Flutter 3.41.5). I reviewed every one side by side with its previous version. All changes come from the fixes above: RTL lines are flush right instead of one glyph per line, the stray one-space indents are gone, and lines next to floats and in mixed inline text fill to the edge. The previous rtl_arabic.png / rtl_hebrew.png had captured the RTL bug.

Tests

test/line_breaking_regression_test.dart: 17 tests; test/line_breaking_perf_and_parity_test.dart: 15 tests (from perf(core): eliminate line-breaking bottleneck on massive unspaced text blocks (#28) #29). Each fix was mutation-checked: reverting it makes at least one test fail.
Local: flutter analyze clean, root+core 2559 passing.

Versions

hyper_render_core 1.13.0
hyper_render 1.13.0 (requires hyper_render_core: ^1.13.0)
Other packages unchanged.

@DrkXo

Character-range highlight geometry from #26 (by @DrkXo): RenderHyperBox.getBoxesForCharRange and debugLineFragments, plus the ellipsisVisibleLength fix on truncated line fragments. hyper_render requires hyper_render_core ^1.13.0. The other packages are unchanged and need no release. CHANGELOG headings, README, MIGRATION_GUIDE, CSS matrix and roadmaps updated.

github-actions · 2026-10-08T06:34:03Z

⚠️ Layout Regression — Budget exceeded (informational)

	Fixture	Budget (ms)	Median (ms)	P95 (ms)
❌	`simple_paragraph`	8	17	19
❌	`mixed_inline`	10	15	16
❌	`float_layout`	12	16	35
❌	`table_20_rows`	14	45	73
✅	`cjk_ruby`	14	12	13
❌	`large_article`	16	40	53

One or more fixtures exceeded the 16 ms budget.

Informational, does not block merge: CI runners use software
rendering and are 2-3x slower than the devices the budgets are
calibrated for. Compare against the base branch; if a fixture
regressed relative to it, profile with:

flutter test benchmark/layout_regression.dart --reporter expanded

and check _performLineLayout / _buildCharacterMapping for
any new O(N²) or O(N log N) paths introduced in this PR.

Both properties inherit in CSS, but the resolver never copied them to child nodes. Line breaking reads them from the text node's own style, so `` had no effect at all.

…er one letter Found while reviewing #29 by dumping debugLineFragments() on a 300px box and checking each line's real width. - Lines ran up to half a glyph past the box. getPositionForOffset returns the nearest caret, not the last one that fits; every full CJK line was 304px in a 300px box. The new _fitPrefixLength helper corrects the probe against real prefix widths. - RTL paragraphs did not wrap. The x = maxWidth probe read an RTL painter from its logical end, so an Arabic paragraph put 72 chars (1,152px) on line one, then one glyph per line. The probe is mirrored for RTL. - A word wider than the line was split after its first letter, leaving a column of one-letter lines. It now breaks after as many characters as fit, as Flutter's Text does. - A word that does not fit beside a float was split the same way ("c" / "onsectetur"). The line now moves below the float, as CSS line boxes do. - Force-split lines kept their trailing space, so centered and right-aligned lines were off by a space. Trailing collapsible spaces are now trimmed, as _splitTextFragment already did. Copying is unaffected; it reads the unsplit fragments. - word-break: break-all fills the line by character instead of first looking for a space. _prefixWidth reads the caret offset: summing getBoxesForSelection(0, k) is O(k) per call and slowed long paragraphs.

github-actions · 2026-10-08T12:01:29Z

⚠️ Layout Regression — Budget exceeded (informational)

	Fixture	Budget (ms)	Median (ms)	P95 (ms)
❌	`simple_paragraph`	8	17	26
❌	`mixed_inline`	10	16	17
❌	`float_layout`	12	16	31
❌	`table_20_rows`	14	44	64
✅	`cjk_ruby`	14	10	12
❌	`large_article`	16	42	61

One or more fixtures exceeded the 16 ms budget.

Informational, does not block merge: CI runners use software
rendering and are 2-3x slower than the devices the budgets are
calibrated for. Compare against the base branch; if a fixture
regressed relative to it, profile with:

flutter test benchmark/layout_regression.dart --reporter expanded

and check _performLineLayout / _buildCharacterMapping for
any new O(N²) or O(N log N) paths introduced in this PR.

github-actions · 2026-10-08T12:01:36Z

❌ Visual Regression Detected

6 golden test(s) failed on Flutter 3.41.5 / ubuntu-22.04.

The rendered output no longer matches the reference images.

If the change is intentional, regenerate the goldens on the
same platform via the Update Goldens workflow dispatch, or run
locally in Docker:

docker run --rm \
  -v $(pwd):/workspace -w /workspace \
  ghcr.io/cirruslabs/flutter:3.41.5 \
  bash -c "apt-get update -qq && \
    apt-get install -y fonts-noto fonts-noto-cjk fonts-roboto && \
    flutter pub get && \
    flutter test test/golden/ --update-goldens"
git add test/golden/goldens/
git commit -m "chore: update golden references (Flutter 3.41.5)"

CSS Text 3 removes collapsible spaces at the start of a line and hangs them at the end. HyperRenderWidget kept both: a line after `` + newline, after ` `, or after an indented `<dt>` started one space in, and the trailing space of a line's last fragment counted toward the width that `text-align: center/right` positions, so right-aligned text (all the RTL goldens) ended one space short of the edge.

github-actions · 2026-10-08T13:57:49Z

⚠️ Layout Regression — Budget exceeded (informational)

	Fixture	Budget (ms)	Median (ms)	P95 (ms)
❌	`simple_paragraph`	8	16	30
❌	`mixed_inline`	10	16	18
❌	`float_layout`	12	16	31
❌	`table_20_rows`	14	34	57
✅	`cjk_ruby`	14	11	14
❌	`large_article`	16	36	60

One or more fixtures exceeded the 16 ms budget.

Informational, does not block merge: CI runners use software
rendering and are 2-3x slower than the devices the budgets are
calibrated for. Compare against the base branch; if a fixture
regressed relative to it, profile with:

flutter test benchmark/layout_regression.dart --reporter expanded

and check _performLineLayout / _buildCharacterMapping for
any new O(N²) or O(N log N) paths introduced in this PR.

github-actions · 2026-10-08T13:58:08Z

❌ Visual Regression Detected

10 golden test(s) failed on Flutter 3.41.5 / ubuntu-22.04.

The rendered output no longer matches the reference images.

If the change is intentional, regenerate the goldens on the
same platform via the Update Goldens workflow dispatch, or run
locally in Docker:

docker run --rm \
  -v $(pwd):/workspace -w /workspace \
  ghcr.io/cirruslabs/flutter:3.41.5 \
  bash -c "apt-get update -qq && \
    apt-get install -y fonts-noto fonts-noto-cjk fonts-roboto && \
    flutter pub get && \
    flutter test test/golden/ --update-goldens"
git add test/golden/goldens/
git commit -m "chore: update golden references (Flutter 3.41.5)"

When a whole fragment did not fit and was moved to the next line, it was placed there without going through the line-start rules, so " inside" after a wrapped `` started one space in. The fragment is now processed again on the fresh line.

github-actions · 2026-10-08T14:03:51Z

⚠️ Layout Regression — Budget exceeded (informational)

	Fixture	Budget (ms)	Median (ms)	P95 (ms)
❌	`simple_paragraph`	8	10	21
✅	`mixed_inline`	10	8	10
✅	`float_layout`	12	10	17
❌	`table_20_rows`	14	23	40
✅	`cjk_ruby`	14	6	7
❌	`large_article`	16	28	62

One or more fixtures exceeded the 16 ms budget.

Informational, does not block merge: CI runners use software
rendering and are 2-3x slower than the devices the budgets are
calibrated for. Compare against the base branch; if a fixture
regressed relative to it, profile with:

flutter test benchmark/layout_regression.dart --reporter expanded

and check _performLineLayout / _buildCharacterMapping for
any new O(N²) or O(N log N) paths introduced in this PR.

github-actions · 2026-10-08T14:04:26Z

❌ Visual Regression Detected

3 golden test(s) failed on Flutter 3.41.5 / ubuntu-22.04.

The rendered output no longer matches the reference images.

If the change is intentional, regenerate the goldens on the
same platform via the Update Goldens workflow dispatch, or run
locally in Docker:

docker run --rm \
  -v $(pwd):/workspace -w /workspace \
  ghcr.io/cirruslabs/flutter:3.41.5 \
  bash -c "apt-get update -qq && \
    apt-get install -y fonts-noto fonts-noto-cjk fonts-roboto && \
    flutter pub get && \
    flutter test test/golden/ --update-goldens"
git add test/golden/goldens/
git commit -m "chore: update golden references (Flutter 3.41.5)"

github-actions · 2026-10-08T14:09:18Z

⚠️ Layout Regression — Budget exceeded (informational)

	Fixture	Budget (ms)	Median (ms)	P95 (ms)
❌	`simple_paragraph`	8	19	26
❌	`mixed_inline`	10	15	16
❌	`float_layout`	12	16	28
❌	`table_20_rows`	14	52	69
✅	`cjk_ruby`	14	12	16
❌	`large_article`	16	47	69

One or more fixtures exceeded the 16 ms budget.

Informational, does not block merge: CI runners use software
rendering and are 2-3x slower than the devices the budgets are
calibrated for. Compare against the base branch; if a fixture
regressed relative to it, profile with:

flutter test benchmark/layout_regression.dart --reporter expanded

and check _performLineLayout / _buildCharacterMapping for
any new O(N²) or O(N log N) paths introduced in this PR.

…ed CJK text Resolves severe UI freezes and layout slowness when rendering documents containing long paragraphs without whitespace (e.g. CJK EPUBs). - Add single-pass native multi-line layout fast path via ICU LineMetrics when no floats encroach on available width. - Bound candidate prefix measurement in fallback line-breaker loop to eliminate quadratic HarfBuzz text shaping overhead. - Ensure loop termination on non-positive line widths by clearing floats or flooring to 1.0. - Exclude trailing whitespace in caret measurement to match native LineMetrics. - Add deterministic parity, intrinsic width, and call-counting tests in test/line_breaking_perf_and_parity_test.dart.

… on massive unspaced text (#28)

… to #29) #29 re-measured every fragment with `measuredSize == null` right before it is placed. A floated block's own text arrives unmeasured (a known gap), so it got a real height and the first line grew from 16px to 24px; this broke flagship_execution_audit_test. Only an oversized tail (estimated infinite width) needs measuring there. Also adds regression tests for the first-block `text-overflow: ellipsis` fix from #29 (parsed HTML, no preceding block) and for the float case, and notes the CJK line-filling behavior change in the core changelog.

github-actions · 2026-10-10T03:09:12Z

⚠️ Layout Regression — Budget exceeded (informational)

	Fixture	Budget (ms)	Median (ms)	P95 (ms)
❌	`simple_paragraph`	8	11	18
❌	`mixed_inline`	10	12	14
❌	`float_layout`	12	13	17
❌	`table_20_rows`	14	31	40
✅	`cjk_ruby`	14	8	11
❌	`large_article`	16	39	73

One or more fixtures exceeded the 16 ms budget.

Informational, does not block merge: CI runners use software
rendering and are 2-3x slower than the devices the budgets are
calibrated for. Compare against the base branch; if a fixture
regressed relative to it, profile with:

flutter test benchmark/layout_regression.dart --reporter expanded

and check _performLineLayout / _buildCharacterMapping for
any new O(N²) or O(N log N) paths introduced in this PR.

github-actions · 2026-10-10T03:09:37Z

❌ Visual Regression Detected

1 golden test(s) failed on Flutter 3.41.5 / ubuntu-22.04.

The rendered output no longer matches the reference images.

If the change is intentional, regenerate the goldens on the
same platform via the Update Goldens workflow dispatch, or run
locally in Docker:

docker run --rm \
  -v $(pwd):/workspace -w /workspace \
  ghcr.io/cirruslabs/flutter:3.41.5 \
  bash -c "apt-get update -qq && \
    apt-get install -y fonts-noto fonts-noto-cjk fonts-roboto && \
    flutter pub get && \
    flutter test test/golden/ --update-goldens"
git add test/golden/goldens/
git commit -m "chore: update golden references (Flutter 3.41.5)"

github-actions · 2026-10-10T03:11:02Z

⚠️ Layout Regression — Budget exceeded (informational)

	Fixture	Budget (ms)	Median (ms)	P95 (ms)
❌	`simple_paragraph`	8	18	25
❌	`mixed_inline`	10	17	20
❌	`float_layout`	12	21	28
❌	`table_20_rows`	14	52	62
✅	`cjk_ruby`	14	12	14
❌	`large_article`	16	55	89

One or more fixtures exceeded the 16 ms budget.

Informational, does not block merge: CI runners use software
rendering and are 2-3x slower than the devices the budgets are
calibrated for. Compare against the base branch; if a fixture
regressed relative to it, profile with:

flutter test benchmark/layout_regression.dart --reporter expanded

and check _performLineLayout / _buildCharacterMapping for
any new O(N²) or O(N log N) paths introduced in this PR.

vietnguyentuan2019 added 3 commits October 8, 2026 19:00

fix(core): inherit word-break and overflow-wrap

fe4a0fd

Both properties inherit in CSS, but the resolver never copied them to child nodes. Line breaking reads them from the text node's own style, so `` had no effect at all.

docs: 1.13.0 changelog and migration notes for the line-breaking fixes

4dac547

chore: regenerate golden references (Flutter 3.41.5) [skip ci]

a797dc6

github-actions Bot and others added 2 commits October 8, 2026 13:58

chore: regenerate golden references (Flutter 3.41.5) [skip ci]

71ad6e9

chore: regenerate golden references (Flutter 3.41.5) [skip ci]

52b9e8d

ci: run the full checks on the regenerated goldens

499e387

vietnguyentuan2019 changed the title ~~release: 1.13.0 — character-range highlight geometry (#26)~~ release: 1.13.0 — character-range highlight geometry (#26) + line-breaking fixes Oct 8, 2026

DrkXo and others added 3 commits October 9, 2026 00:58

Merge pull request #29: eliminate the O(N^2) line-breaking bottleneck…

1feb2fc

… on massive unspaced text (#28)

chore: regenerate golden references (Flutter 3.41.5) [skip ci]

87ffb69

ci: run the full checks with #29 merged

d2fa5cf

vietnguyentuan2019 merged commit ef062d9 into main Oct 10, 2026
9 checks passed

vietnguyentuan2019 mentioned this pull request Oct 10, 2026

[Bug / Perf]: Line-breaking bottleneck on massive unspaced text blocks (CJK / Gutenberg EPUBs) #28

Closed

vietnguyentuan2019 deleted the release/1.13.0 branch October 10, 2026 09:03

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release: 1.13.0 — character-range highlight geometry (#26) + line-breaking fixes - #27

release: 1.13.0 — character-range highlight geometry (#26) + line-breaking fixes#27
vietnguyentuan2019 merged 15 commits into
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⚠️ Layout Regression — Budget exceeded (informational)

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