63 lines
2.2 KiB
JavaScript
63 lines
2.2 KiB
JavaScript
import { isNodePattern, throwError } from "@jimp/utils";
|
|
|
|
/**
|
|
* Applies a true Gaussian blur to the image (warning: this is VERY slow)
|
|
* @param {number} r the pixel radius of the blur
|
|
* @param {function(Error, Jimp)} cb (optional) a callback for when complete
|
|
* @returns {Jimp} this for chaining of methods
|
|
*/
|
|
export default (() => ({
|
|
gaussian(r, cb) {
|
|
// http://blog.ivank.net/fastest-gaussian-blur.html
|
|
if (typeof r !== "number") {
|
|
return throwError.call(this, "r must be a number", cb);
|
|
}
|
|
if (r < 1) {
|
|
return throwError.call(this, "r must be greater than 0", cb);
|
|
}
|
|
const rs = Math.ceil(r * 2.57); // significant radius
|
|
const range = rs * 2 + 1;
|
|
const rr2 = r * r * 2;
|
|
const rr2pi = rr2 * Math.PI;
|
|
const weights = [];
|
|
for (let y = 0; y < range; y++) {
|
|
weights[y] = [];
|
|
for (let x = 0; x < range; x++) {
|
|
const dsq = (x - rs) ** 2 + (y - rs) ** 2;
|
|
weights[y][x] = Math.exp(-dsq / rr2) / rr2pi;
|
|
}
|
|
}
|
|
for (let y = 0; y < this.bitmap.height; y++) {
|
|
for (let x = 0; x < this.bitmap.width; x++) {
|
|
let red = 0;
|
|
let green = 0;
|
|
let blue = 0;
|
|
let alpha = 0;
|
|
let wsum = 0;
|
|
for (let iy = 0; iy < range; iy++) {
|
|
for (let ix = 0; ix < range; ix++) {
|
|
const x1 = Math.min(this.bitmap.width - 1, Math.max(0, ix + x - rs));
|
|
const y1 = Math.min(this.bitmap.height - 1, Math.max(0, iy + y - rs));
|
|
const weight = weights[iy][ix];
|
|
const idx = y1 * this.bitmap.width + x1 << 2;
|
|
red += this.bitmap.data[idx] * weight;
|
|
green += this.bitmap.data[idx + 1] * weight;
|
|
blue += this.bitmap.data[idx + 2] * weight;
|
|
alpha += this.bitmap.data[idx + 3] * weight;
|
|
wsum += weight;
|
|
}
|
|
const idx = y * this.bitmap.width + x << 2;
|
|
this.bitmap.data[idx] = Math.round(red / wsum);
|
|
this.bitmap.data[idx + 1] = Math.round(green / wsum);
|
|
this.bitmap.data[idx + 2] = Math.round(blue / wsum);
|
|
this.bitmap.data[idx + 3] = Math.round(alpha / wsum);
|
|
}
|
|
}
|
|
}
|
|
if (isNodePattern(cb)) {
|
|
cb.call(this, null, this);
|
|
}
|
|
return this;
|
|
}
|
|
}));
|
|
//# sourceMappingURL=index.js.map
|