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