s2maps-gpu/dist/workers/source/texturePack.js

S2 Maps GPU - An open source, high-performance, and GPU-accelerated map engine for rendering large-scale, interactive maps.

/**
 * Texture pack stores fonts and builds out SDF characters onto a texture sheet
 * each time we encounter a new character, we need to build the fills and strokes
 * and let the main painting thread know about the update
 * each font will have its own vertical row, and if a row is filled, we start a new one
 * the horizontal space is 2048 and we start a new row
 */
export default class TexturePack {
    height = 0;
    maxWidth = 2048;
    spaces = {};
    /**
     * Add a glyph
     * @param width - width of glyph
     * @param height - height of glyph
     * @returns the position of the glyph in the texture
     */
    addGlyph(width, height) {
        // create a box object
        const bbox = [0, 0, width, height];
        // if spaces doesn't have the height OR the width of the space is maxed out, create new
        if (this.spaces[height] === undefined ||
            this.spaces[height].widthOffset + width > this.maxWidth) {
            this.spaces[height] = { heightOffset: this.height + 1, widthOffset: 0 };
            // update height offset of texture
            this.height += height + 1;
        }
        // add to the space
        const { widthOffset, heightOffset } = this.spaces[height];
        bbox[0] = widthOffset;
        bbox[1] = heightOffset;
        // update width offset of row
        this.spaces[height].widthOffset += width + 1;
        // return the textures position
        return [bbox[0], bbox[1]];
    }
}