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/** |
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* Color utility functions for CSS generation and color manipulation |
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*/ |
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|
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/** |
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* Apply alpha (opacity) to a color string. |
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* Supports hex (#RGB, #RRGGBB), rgb(), rgba(), hsl(), hsla(), and named colors. |
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* For hex colors, appends the alpha hex component. For other formats, uses CSS color-mix or fallback. |
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* |
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* @param color - Color string in any CSS format |
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* @param alphaHex - 2-digit hex representation of alpha (e.g., "26" for ~15% opacity) |
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* @returns Color string with alpha applied |
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*/ |
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export function applyAlpha(color: string, alphaHex: string): string { |
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if (!color || !alphaHex) return color |
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|
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if (!/^[0-9A-Fa-f]{2}$/.test(alphaHex)) { |
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return color |
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} |
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|
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// If it's a hex color (#RGB or #RRGGBB), append the alpha hex directly |
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if (color.startsWith('#')) { |
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if (color.length === 4) { |
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// Expand 3-digit hex shorthand #RGB to #RRGGBB |
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const expanded = `#${color[1]}${color[1]}${color[2]}${color[2]}${color[3]}${color[3]}` |
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return `${expanded}${alphaHex}` |
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} |
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if (color.length === 7) { |
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// Full 6-digit hex, append alpha hex |
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return `${color}${alphaHex}` |
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} |
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// Already has alpha (5 or 8 chars), return as-is |
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return color |
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} |
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|
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// For rgb, rgba, hsl, hsla, or named colors, use CSS color-mix (modern approach) |
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// This is more robust than trying to parse and convert formats |
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// Fallback: use rgba with the color-mix syntax understood by most modern browsers |
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const alphaDecimal = parseInt(alphaHex, 16) / 255 |
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return `color-mix(in srgb, ${color} ${(alphaDecimal * 100).toFixed(1)}%, transparent)` |
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} |
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