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SVG: read rgb() with a fractional or percentage alpha - #2197
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andersonhc merged 4 commits intoNov 14, 2026
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The 4th value of fpdf2's own rgb(R, G, B, A) is an alpha from 0 to 255, so rgb(0,0,0, 0.5), which Mermaid writes in sequence diagrams, failed with ValueError. A fraction or a percentage can only be the 0-1 alpha that CSS Color 4 allows in rgb().
andersonhc
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Nov 13, 2026
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One small compatibility question: +100 previously used the legacy 0–255 alpha scale, but now becomes fully opaque because isdigit() rejects the leading +. The new result matches CSS, so this may be intentional. Should signed integers retain the legacy behavior too? A test would help make that choice explicit.
andersonhc
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Nov 14, 2026
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Mermaid writes
stroke="rgb(0,0,0, 0.5)"around therectblocks of sequence diagrams, as in the diagrams of the Making Embedded Systems repository. It fails withValueError: invalid literal for int() with base 10: '0.5'.svgcolor()sends anrgb()with commas to fpdf2's ownrgb(R, G, B, A), whose 4th value is an alpha from 0 to 255, as in thergb(200, 240, 255, 100)of issue #480. A fraction or a percentage can only be the 0-1 alpha that CSS Color 4 allows inrgb(), so such a color is now read likergba(). An integer alpha is still read from 0 to 255.New cases in
parameters.pycoverrgb(0,0,0, 0.5)andrgb(255, 0, 0, 25%); both fail without the change.