image-in-browser/lib/formats/gif/gif-color-map.js

Package for encoding / decoding images, transforming images, applying filters, drawing primitives on images on the client side (no need for server Node.js)

import { ColorUint8 } from '../../color/color-uint8.js';
import { PaletteUint8 } from '../../image/palette-uint8.js';
export class GifColorMap {
    get numColors() {
        return this._numColors;
    }
    get palette() {
        return this._palette;
    }
    get bitsPerPixel() {
        return this._bitsPerPixel;
    }
    set transparent(v) {
        this._transparent = v;
    }
    get transparent() {
        return this._transparent;
    }
    constructor(numColors, palette) {
        this._numColors = numColors;
        this._palette = palette !== null && palette !== void 0 ? palette : new PaletteUint8(numColors, 3);
        this._bitsPerPixel = GifColorMap.bitSize(numColors);
    }
    static bitSize(n) {
        for (let i = 1; i <= 8; i++) {
            if (1 << i >= n) {
                return i;
            }
        }
        return 0;
    }
    static from(other) {
        const palette = PaletteUint8.from(other._palette);
        const r = new GifColorMap(other.numColors, palette);
        r._bitsPerPixel = other._bitsPerPixel;
        r._transparent = other._transparent;
        return r;
    }
    getColor(index) {
        const r = this.getRed(index);
        const g = this.getGreen(index);
        const b = this.getBlue(index);
        const a = this.getAlpha(index);
        return ColorUint8.rgba(r, g, b, a);
    }
    setColor(index, r, g, b) {
        this._palette.setRgb(index, r, g, b);
    }
    findColor(r, g, b, a) {
        let closestDistance = -1;
        let closestIndex = -1;
        for (let i = 0; i < this._numColors; ++i) {
            const pr = this._palette.getRed(i);
            const pg = this._palette.getGreen(i);
            const pb = this._palette.getBlue(i);
            const pa = this._palette.getAlpha(i);
            if (pr === r && pg === g && pb === b && pa === a) {
                return i;
            }
            const dr = r - pr;
            const dg = g - pg;
            const db = b - pb;
            const da = a - pa;
            const d2 = dr * dr + dg * dg + db * db + da * da;
            if (closestIndex === -1 || d2 < closestDistance) {
                closestIndex = i;
                closestDistance = d2;
            }
        }
        return closestIndex;
    }
    getRed(color) {
        return Math.trunc(this._palette.getRed(color));
    }
    getGreen(color) {
        return Math.trunc(this._palette.getGreen(color));
    }
    getBlue(color) {
        return Math.trunc(this._palette.getBlue(color));
    }
    getAlpha(color) {
        return color === this._transparent ? 0 : 255;
    }
    getPalette() {
        if (this._transparent === undefined) {
            return this._palette;
        }
        const p = new PaletteUint8(this._palette.numColors, 4);
        const l = this._palette.numColors;
        for (let i = 0; i < l; ++i) {
            p.setRgba(i, this.getRed(i), this.getGreen(i), this.getBlue(i), this.getAlpha(i));
        }
        return p;
    }
}
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