Function TinySDF

docs/app/js/sanddance-app.js:105750–105779

(fontSize, buffer, radius, cutoff, fontFamily, fontWeight)

module.exports.default = TinySDF;
var INF = 1e20;
function TinySDF(fontSize, buffer, radius, cutoff, fontFamily, fontWeight) {
    this.fontSize = fontSize || 24;
    this.buffer = buffer === undefined ? 3 : buffer;
    this.cutoff = cutoff || 0.25;
    this.fontFamily = fontFamily || "sans-serif";
    this.fontWeight = fontWeight || "normal";
    this.radius = radius || 8;
    // For backwards compatibility, we honor the implicit contract that the
    // size of the returned bitmap will be fontSize + buffer * 2
    var size = this.size = this.fontSize + this.buffer * 2;
    // Glyphs may be slightly larger than their fontSize. The canvas already
    // has buffer space, but create extra buffer space in the output grid for the
    // "halo" to extend into (if metric extraction is enabled)
    var gridSize = size + this.buffer * 2;
    this.canvas = document.createElement("canvas");
    this.canvas.width = this.canvas.height = size;
    this.ctx = this.canvas.getContext("2d");
    this.ctx.font = this.fontWeight + " " + this.fontSize + "px " + this.fontFamily;
    this.ctx.textAlign = "left"; // Necessary so that RTL text doesn't have different alignment
    this.ctx.fillStyle = "black";
    // temporary arrays for the distance transform
    this.gridOuter = new Float64Array(gridSize * gridSize);
    this.gridInner = new Float64Array(gridSize * gridSize);
    this.f = new Float64Array(gridSize);
    this.z = new Float64Array(gridSize + 1);
    this.v = new Uint16Array(gridSize);
    this.useMetrics = this.ctx.measureText("A").actualBoundingBoxLeft !== undefined;
    // hack around https://bugzilla.mozilla.org/show_bug.cgi?id=737852
    this.middle = Math.round(size / 2 * (navigator.userAgent.indexOf("Gecko/") >= 0 ? 1.2 : 1));
}
function prepareGrids(imgData, width, height, glyphWidth, glyphHeight, gridOuter, gridInner) {
    // Initialize grids outside the glyph range to alpha 0
    gridOuter.fill(INF, 0, width * height);