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