107 lines
3.5 KiB
JavaScript
107 lines
3.5 KiB
JavaScript
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/**
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* Converts from rgba hex value to an array of four numbers representing r, g, b, and a respectively.
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*
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* @param {string} hex the hex value.
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* @returns {number[]} the resulting components of the hex value.
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*/
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function rgbaHexToRgba(hex) {
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if (hex.startsWith("#")) {
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hex = hex.substring(1);
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if (hex.length > 8) {
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throw new Error("Invalid hex syntax (length).");
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}
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} else {
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throw new Error("Invalid hex syntax (missing pound).");
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}
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for (let i = hex.length; i < 8; i++) {
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hex = "0" + hex;
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}
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let remaining = hex.length;
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let result = [0, 0, 0, 0];
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result[3] = parseInt(hex.substring(remaining -= 2, remaining + 2), 16);
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result[2] = parseInt(hex.substring(remaining -= 2, remaining + 2), 16);
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result[1] = parseInt(hex.substring(remaining -= 2, remaining + 2), 16);
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result[0] = parseInt(hex.substring(remaining -= 2, remaining + 2), 16);
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return result;
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}
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/**
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*
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* @param {string} hex the hex value.
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* @returns {number[]} the resulting r, g, and b components.
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*/
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function rgbHexToRgba(hex) {
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const result = rgbaHexToRgba(hex + "FF");
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return result;
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}
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/**
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* Converts from the CSS rgba call to an array of four numbers representing r, g, b and a.
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*
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* @param {string} rgba The CSS rgba(r,g,b,a) call.
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* @returns {number[]} the rgba components.
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*/
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function cssRgbaToRgba(rgba) {
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const cssRgbaRegex = /rgba\((\d+),(\d+),(\d+),(\d+)\)/;
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try {
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const matches = rgba.match(cssRgbaRegex);
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return [parseInt(matches[1]), parseInt(matches[2]), parseInt(matches[3]), parseInt(matches[4])];
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} catch (error) {
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throw new Error("Could not parse the given css rgba function call: " + error.message);
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}
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}
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/**
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* Converts from the CSS rgb call to an array of four numbers representing r, g, b and a.
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*
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* @param {string} rgb The CSS rgb(r,g,b) call.
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* @returns {number[]} the rgba components.
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*/
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function cssRgbToRgba(rgb) {
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const cssRgbRegex = /rgb\((\d+),(\d+),(\d+)\)/;
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try {
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const matches = rgb.match(cssRgbRegex);
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return [parseInt(matches[1]), parseInt(matches[2]), parseInt(matches[3]), 255];
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} catch (error) {
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throw new Error("Could not parse the given css rgb function call: " + error.message);
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}
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}
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/**
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* Converts a given array of r, g, b, and a components into a hex string.
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*
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* @param {number[]} rgba an array with red, green, blue, and alpha components in that order.
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* @returns {string} The resulting hex value.
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*/
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function rgbaToHexRgba(rgba) {
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const filler = (hex) => hex.length < 2 ? "0" + hex : hex;
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return "#" + filler(rgba[0].toString(16)) + filler(rgba[1].toString(16)) + filler(rgba[2].toString(16)) + filler(rgba[3].toString(16));
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}
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/**
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* Converts a css rgb, rgba, hex, or rgba hex to a rgba array.
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*
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* For hex, we assume there is no alpha channel unless the hex value is not minimized.
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*
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* @param {string} color The string that contains the color information.
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* @returns {number[]} an array that contains the r, g, b and a components.
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*/
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function parseColor(color) {
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if (color.startsWith("rgba(")) {
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return cssRgbaToRgba(color);
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} else if (color.startsWith("rgb(")) {
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return cssRgbToRgba(color);
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} else if (color.startsWith("#")) {
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if (color.length === 9) {
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return rgbaHexToRgba(color);
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} else {
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return rgbHexToRgba(color);
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}
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}
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throw new Error("Could not parse to an rgba value.");
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}
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/**@module */
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export { rgbaHexToRgba, rgbHexToRgba, cssRgbaToRgba, cssRgbToRgba, rgbaToHexRgba, parseColor }; |