Memoize CharactersPerSecond and PixelWidth in SubtitleLineViewModel (grid binding perf)#11675
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Memoize CharactersPerSecond and PixelWidth in SubtitleLineViewModel (grid binding perf)#11675niksedk wants to merge 1 commit into
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Both getters are bound directly into subtitle-grid cells and Avalonia re-evaluates them on every cell repaint: - CharactersPerSecond is hit multiple times per row repaint (CPS cell text, CpsBackgroundBrush, and the DurationBackgroundBrush SE4 fallback), each running SubtitleTextInfoHelper.GetCharactersPerSecond. - PixelWidth shapes text with SkiaSharp (SKShaper.Shape) and is read both by the pixel-width column and by TextBackgroundBrush. Add value-keyed memoization (CPS keyed on Text/StartTime/EndTime; PixelWidth keyed on Text + the width font name/size) so repeated reads with unchanged inputs reuse the result. The keys are the actual inputs, so the cache self-invalidates without relying on PropertyChanged ordering; behavior is unchanged. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
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Optimizes two hot per-row bindings in the subtitle grid. Both getters on
SubtitleLineViewModelare bound straight into grid cells, and Avalonia re-evaluates them on every cell repaint.CharactersPerSecondis hit several times per row repaint — the CPS cell text binding,CpsBackgroundBrush, and theDurationBackgroundBrushSE4 fallback all read it, each runningSubtitleTextInfoHelper.GetCharactersPerSecond.PixelWidthshapes text with SkiaSharp (SKShaper.Shape) on every read and is consumed both by the pixel-width column and byTextBackgroundBrush's "too wide" check.Change
Add value-keyed memoization:
Text/StartTime/EndTimeText+ the configured width font name/sizeThe cache keys are the actual computation inputs, so it self-invalidates when any input changes — no reliance on
PropertyChangedordering, and behavior is identical. Repeated reads with unchanged inputs (the common case during repaint/scroll) reuse the result instead of recomputing.🤖 Generated with Claude Code