billboard.js/dist-esm/canvas/color.js

Re-usable easy interface JavaScript chart library, based on D3 v4+

/*!
* Copyright (c) 2017 ~ present NAVER Corp.
 * billboard.js project is licensed under the MIT license
 * 
 * billboard.js, JavaScript chart library
 * https://naver.github.io/billboard.js/
 * 
 * @version 4.1.1
*/
import { window as win } from "../module/browser.js";
import { isNumber } from "../module/util/type-checks.js";
//#region src/canvas/color.ts
/**
* Copyright (c) 2017 ~ present NAVER Corp.
* billboard.js project is licensed under the MIT license
*/
let colorParserContext;
/**
* Apply opacity to CSS color values canvas can parse directly.
* @param {string} color CSS color value
* @param {number} opacity Stop opacity
* @returns {string} Color with alpha when convertible
* @private
*/
function withOpacity(color, opacity) {
	if (!isNumber(opacity) || opacity >= 1) return color;
	const hex = color.match(/^#([\da-f]{3}|[\da-f]{6})$/i);
	if (hex) {
		const matches = (hex[1].length === 3 ? hex[1].split("").map((v) => v + v).join("") : hex[1]).match(/.{2}/g);
		if (!matches) return color;
		return `rgba(${matches.map((v) => parseInt(v, 16)).join(",")},${opacity})`;
	}
	if (/^rgb\(/i.test(color)) return color.replace(/^rgb\((.*)\)$/i, `rgba($1,${opacity})`);
	if (/^rgba\(/i.test(color)) return color.replace(/^rgba\((.*),\s*([\d.]+)\)$/i, (_, rgb, alpha) => `rgba(${rgb},${Number(alpha) * opacity})`);
	const parsed = parseCanvasColor(color);
	if (parsed && parsed !== color) return withOpacity(parsed, opacity);
	return color;
}
/**
* Parse any CSS color value that canvas can understand.
* @param {string} color CSS color value
* @returns {string|null} Normalized canvas color
* @private
*/
function parseCanvasColor(color) {
	if (!win.document) return null;
	if (colorParserContext === void 0) colorParserContext = win.document.createElement("canvas").getContext("2d");
	if (!colorParserContext) return null;
	colorParserContext.fillStyle = "#000";
	colorParserContext.fillStyle = color;
	const parsedOnBlack = colorParserContext.fillStyle;
	colorParserContext.fillStyle = "#fff";
	colorParserContext.fillStyle = color;
	return parsedOnBlack === colorParserContext.fillStyle ? parsedOnBlack : null;
}
//#endregion
export { parseCanvasColor, withOpacity };