45 lines
1.2 KiB
JavaScript
45 lines
1.2 KiB
JavaScript
/**
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* Convert hex color to rgb array
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*
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* @param hex string
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* @returns array|null
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*/
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export const hexToRgb = (hex) => {
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// Expand shorthand form (e.g. "03F") to full form (e.g. "0033FF")
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const shorthandRegex = /^#?([a-f\d])([a-f\d])([a-f\d])$/i;
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const fullHex = hex.replace(shorthandRegex, (_m, r, g, b) => r + r + g + g + b + b);
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const result = /^#?([a-f\d]{2})([a-f\d]{2})([a-f\d]{2})$/i.exec(fullHex);
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return result
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? [parseInt(result[1], 16), parseInt(result[2], 16), parseInt(result[3], 16)]
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: null;
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};
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export const textColorForBackground = (backgroundColor) => {
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const [r, g, b] = hexToRgb(backgroundColor);
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if (r + g + b > 500) {
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return '#333333';
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}
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return '#FFFFFF';
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};
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/**
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* Check whether a color matches the expected hex format
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*
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* This matches any hex (0-9 and A-F) value which is either 3 or 6 characters in length
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*
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* An empty string will return `null` which means that this is neither valid nor invalid.
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* This is useful for forms resetting the validation state
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*
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* @param color string = ''
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*
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* @returns {null|boolean}
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*/
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export const validateHexColor = (color = '') => {
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if (!color) {
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return null;
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}
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return /^#([0-9A-F]{3}){1,2}$/i.test(color);
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};
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