39 lines
949 B
JavaScript
39 lines
949 B
JavaScript
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import { isNodePattern } from '@jimp/utils';
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/**
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* Apply a ordered dithering effect
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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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function dither(cb) {
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const rgb565Matrix = [1, 9, 3, 11, 13, 5, 15, 7, 4, 12, 2, 10, 16, 8, 14, 6];
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this.scanQuiet(0, 0, this.bitmap.width, this.bitmap.height, function(
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x,
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y,
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idx
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) {
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const thresholdId = ((y & 3) << 2) + (x % 4);
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const dither = rgb565Matrix[thresholdId];
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this.bitmap.data[idx] = Math.min(this.bitmap.data[idx] + dither, 0xff);
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this.bitmap.data[idx + 1] = Math.min(
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this.bitmap.data[idx + 1] + dither,
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0xff
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);
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this.bitmap.data[idx + 2] = Math.min(
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this.bitmap.data[idx + 2] + dither,
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0xff
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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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export default () => ({
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dither565: dither,
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dither16: dither
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});
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