49 lines
1.5 KiB
JavaScript
Executable File
49 lines
1.5 KiB
JavaScript
Executable File
import { isNodePattern, throwError } from "@jimp/utils";
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/**
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* Applies a minimum color threshold to a greyscale image. Converts image to greyscale by default
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* @param {number} options object
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* max: A number auto limited between 0 - 255
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* replace: (optional) A number auto limited between 0 - 255 (default 255)
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* autoGreyscale: (optional) A boolean whether to apply greyscale beforehand (default true)
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* @param {number} cb (optional) a callback for when complete
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* @return {this} this for chaining of methods
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*/
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export default () => ({
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threshold({ max, replace = 255, autoGreyscale = true }, cb) {
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if (typeof max !== "number") {
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return throwError.call(this, "max must be a number", cb);
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}
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if (typeof replace !== "number") {
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return throwError.call(this, "replace must be a number", cb);
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}
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if (typeof autoGreyscale !== "boolean") {
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return throwError.call(this, "autoGreyscale must be a boolean", cb);
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}
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max = this.constructor.limit255(max);
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replace = this.constructor.limit255(replace);
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if (autoGreyscale) {
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this.greyscale();
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}
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this.scanQuiet(0, 0, this.bitmap.width, this.bitmap.height, (x, y, idx) => {
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const grey =
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this.bitmap.data[idx] < max ? this.bitmap.data[idx] : replace;
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this.bitmap.data[idx] = grey;
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this.bitmap.data[idx + 1] = grey;
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this.bitmap.data[idx + 2] = grey;
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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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