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32 lines
811 B
JavaScript
32 lines
811 B
JavaScript
export function multiplyAlpha(pixel) {
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return pixel.map((channel, i) => {
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// Pass the alpha channel through unchanged
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if (i === 3) return channel;
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// Otherwise, multiply by alpha
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return channel * pixel[3];
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});
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}
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export function unmultiplyAlpha(pixel) {
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return pixel.map((channel, i) => {
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// Pass the alpha channel through unchanged
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if (i === 3) return channel;
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// Avoid divide-by-zero
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if (pixel[3] === 0) return channel;
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// Divide by alpha
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return channel / pixel[3];
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});
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}
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export function clamp01(value) {
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if (value < 0) return 0;
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if (value > 1) return 1;
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return value;
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}
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const toPercent = (num) => `${num * 100}%`;
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export const toCSSColor = (pixel) =>
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`rgb(${toPercent(pixel[0])} ${toPercent(pixel[1])} ${toPercent(pixel[2])} / ${
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pixel[3]
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})`;
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