rc-js-util/bin/esm/colors/rgba-color-packer.js

A collection of TS and C++ utilities to help writing performant and correct applications, achieved through strict typing and (removable) invariant checking.

import { ERgbaMasks, ERgbaShift } from "./e-rgba-masks.js";
/**
 * @public
 * Utility for packing and unpacking RGBA into int32 with one byte per channel.
 */
export class RgbaColorPacker {
    /**
     * @param color - Bit packed color.
     * @returns a value between 0 - 255 representing the red component.
     */
    static unpackR(color) {
        return (color & ERgbaMasks.R) >>> ERgbaShift.R;
    }
    /**
     * @param color - Bit packed color.
     * @returns a value between 0 - 255 representing the green component.
     */
    static unpackG(color) {
        return (color & ERgbaMasks.G) >>> ERgbaShift.G;
    }
    /**
     * @param color - Bit packed color.
     * @returns a value between 0 - 255 representing the blue component.
     */
    static unpackB(color) {
        return (color & ERgbaMasks.B) >>> ERgbaShift.B;
    }
    /**
     * @param color - Bit packed color.
     * @returns a value between 0 - 255 representing the alpha component.
     */
    static unpackA(color) {
        return (color & ERgbaMasks.A) >>> ERgbaShift.A;
    }
    /**
     *
     * @param r - Red 0 - 255.
     * @param g - Green 0 - 255.
     * @param b - Blue 0 - 255.
     * @param a - Alpha 0 - 255.
     */
    static packColor(r, g, b, a) {
        return (r << ERgbaShift.R) |
            (g << ERgbaShift.G) |
            (b << ERgbaShift.B) |
            (a << ERgbaShift.A);
    }
    /**
     * Given a packed color, produce a dom color string like `rgba(255, 255, 255, 1)`.
     */
    static makeDomColorString(color) {
        const tmp = RgbaColorPacker.colorStringTmp;
        tmp[1] = (color & ERgbaMasks.R) >>> ERgbaShift.R;
        tmp[3] = (color & ERgbaMasks.G) >>> ERgbaShift.G;
        tmp[5] = (color & ERgbaMasks.B) >>> ERgbaShift.B;
        tmp[7] = ((color & ERgbaMasks.A) >>> ERgbaShift.A) * 0.00392156862745098; // divide by 255
        return tmp.join("");
    }
    /**
     * Given a packed color, produce a dom color string like `#FF0000`.
     *
     * @remarks
     * Made up of only 6 components, the alpha channel will be masked out.
     */
    static getHexColorString(value) {
        if (value !== value) {
            return "NaN";
        }
        // mask off the alpha channel
        value = value & (~ERgbaMasks.A);
        // switch from ABGR to RGB
        value = ((value & 0xFF) << 16) | (value & 0xFF00) | ((value & 0xFF0000) >> 16);
        RgbaColorPacker.hexColorTmp[1] = value
            .toString(16)
            .toUpperCase()
            .padStart(6, "0");
        return RgbaColorPacker.hexColorTmp.join("");
    }
    static generateRandomPackedRGBA() {
        return ((Math.random() * 255) << ERgbaShift.R) |
            ((Math.random() * 255) << ERgbaShift.G) |
            ((Math.random() * 255) << ERgbaShift.B) |
            ((Math.random() * 255) << ERgbaShift.A);
    }
}
RgbaColorPacker.colorStringTmp = ["rgba(", 1, ",", 3, ",", 5, ",", 7, ")"];
RgbaColorPacker.hexColorTmp = ["#", 0];
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