index.js
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import { throwError, isNodePattern } from '@jimp/utils';
export default () => ({
/**
* Blits a source image on to this image
* @param {Jimp} src the source Jimp instance
* @param {number} x the x position to blit the image
* @param {number} y the y position to blit the image
* @param {number} srcx (optional) the x position from which to crop the source image
* @param {number} srcy (optional) the y position from which to crop the source image
* @param {number} srcw (optional) the width to which to crop the source image
* @param {number} srch (optional) the height to which to crop the source image
* @param {function(Error, Jimp)} cb (optional) a callback for when complete
* @returns {Jimp} this for chaining of methods
*/
blit(src, x, y, srcx, srcy, srcw, srch, cb) {
if (!(src instanceof this.constructor)) {
return throwError.call(this, 'The source must be a Jimp image', cb);
}
if (typeof x !== 'number' || typeof y !== 'number') {
return throwError.call(this, 'x and y must be numbers', cb);
}
if (typeof srcx === 'function') {
cb = srcx;
srcx = 0;
srcy = 0;
srcw = src.bitmap.width;
srch = src.bitmap.height;
} else if (
typeof srcx === typeof srcy &&
typeof srcy === typeof srcw &&
typeof srcw === typeof srch
) {
srcx = srcx || 0;
srcy = srcy || 0;
srcw = srcw || src.bitmap.width;
srch = srch || src.bitmap.height;
} else {
return throwError.call(
this,
'srcx, srcy, srcw, srch must be numbers',
cb
);
}
// round input
x = Math.round(x);
y = Math.round(y);
// round input
srcx = Math.round(srcx);
srcy = Math.round(srcy);
srcw = Math.round(srcw);
srch = Math.round(srch);
const maxWidth = this.bitmap.width;
const maxHeight = this.bitmap.height;
const baseImage = this;
src.scanQuiet(srcx, srcy, srcw, srch, function(sx, sy, idx) {
const xOffset = x + sx - srcx;
const yOffset = y + sy - srcy;
if (
xOffset >= 0 &&
yOffset >= 0 &&
maxWidth - xOffset > 0 &&
maxHeight - yOffset > 0
) {
const dstIdx = baseImage.getPixelIndex(xOffset, yOffset);
const src = {
r: this.bitmap.data[idx],
g: this.bitmap.data[idx + 1],
b: this.bitmap.data[idx + 2],
a: this.bitmap.data[idx + 3]
};
const dst = {
r: baseImage.bitmap.data[dstIdx],
g: baseImage.bitmap.data[dstIdx + 1],
b: baseImage.bitmap.data[dstIdx + 2],
a: baseImage.bitmap.data[dstIdx + 3]
};
baseImage.bitmap.data[dstIdx] =
((src.a * (src.r - dst.r) - dst.r + 255) >> 8) + dst.r;
baseImage.bitmap.data[dstIdx + 1] =
((src.a * (src.g - dst.g) - dst.g + 255) >> 8) + dst.g;
baseImage.bitmap.data[dstIdx + 2] =
((src.a * (src.b - dst.b) - dst.b + 255) >> 8) + dst.b;
baseImage.bitmap.data[dstIdx + 3] = this.constructor.limit255(
dst.a + src.a
);
}
});
if (isNodePattern(cb)) {
cb.call(this, null, this);
}
return this;
}
});