fix(text): avoid spurious measuring in _measureChar when only kerning-irrelevant entries are missing#11028
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jiayihu wants to merge 2 commits into
Open
fix(text): avoid spurious measuring in _measureChar when only kerning-irrelevant entries are missing#11028jiayihu wants to merge 2 commits into
jiayihu wants to merge 2 commits into
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…-irrelevant entries are missing
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asturur
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Jun 29, 2026
| if (previousChar && fontCache.has(previousChar)) { | ||
| previousWidth = fontCache.get(previousChar); | ||
| if (hasPrevChar && fontCache.has(previousChar!)) { | ||
| previousWidth = fontCache.get(previousChar!); |
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is incredible that TS still can't catch this.
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My bad (or GLM's so ultimately mine eheh). It was using Boolean, which defeats the TS control flow analysis. Using raw !! preserves it. Still needed for Maps though as there is no control flow analysis for Map.has
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Disclosure: I found out the issue during work but I fully asked GLM 5.2 to port the fix back to fabric, add tests and open the PR using the repo skill.
Summary
_measureCharwas treating missingpreviousWidthorcoupleWidthas a cache miss even when kerning was irrelevant (no usable previous char, or previous char with a different style). On a pure single-character cache hit this forced an unnecessary fetch of the measuring context and extra_setTextStyles/measureTextbookkeeping. The fix only builds and reads the kerning pair when a same-style previous char exists, and only enters the measuring path when the single-character width is missing or a same-style kerning pair actually needs measuring.Changes
src/shapes/Text/Text.ts: rewrote the_measureCharcache/measure logic so the couple key andpreviousWidthare only built/read whenpreviousCharexists, and the measuring path is gated onwidth === undefined || (stylesAreEqual && coupleWidth === undefined).src/shapes/Text/Text.spec.ts: added two tests covering the regression — one asserting_setTextStylesis not called when only kerning-irrelevant entries are missing, and one assertingmeasureTextis invoked forpreviousWidthandcoupleWidth(and not for an already-cached single char) when both are undefined.