import { JimpClass, JimpClassSchema } from "@jimp/types";
import { z } from "zod";
const MaskOptionsObjectSchema = z.object({
src: JimpClassSchema,
/** the x position to draw the image */
x: z.number().optional(),
/** the y position to draw the image */
y: z.number().optional(),
});
const MaskOptionsSchema = z.union([JimpClassSchema, MaskOptionsObjectSchema]);
export type MaskOptions = z.infer<typeof MaskOptionsSchema>;
export const methods = {
/**
* Masks a source image on to this image using average pixel colour. A completely black pixel on the mask will turn a pixel in the image completely transparent.
* @param src the source Jimp instance
* @param x the horizontal position to blit the image
* @param y the vertical position to blit the image
* @example
* ```ts
* import { Jimp } from "jimp";
*
* const image = await Jimp.read("test/image.png");
* const mask = await Jimp.read("test/mask.png");
*
* image.mask(mask);
* ```
*/
mask<I extends JimpClass>(image: I, options: MaskOptions) {
MaskOptionsSchema.parse(options);
let src: JimpClass;
let x: number;
let y: number;
if ("bitmap" in options) {
src = options as unknown as JimpClass;
x = 0;
y = 0;
} else {
src = options.src as unknown as JimpClass;
x = options.x ?? 0;
y = options.y ?? 0;
}
// round input
x = Math.round(x);
y = Math.round(y);
const w = image.bitmap.width;
const h = image.bitmap.height;
src.scan(function (sx, sy, idx) {
const destX = x + sx;
const destY = y + sy;
if (destX >= 0 && destY >= 0 && destX < w && destY < h) {
const dstIdx = image.getPixelIndex(destX, destY);
const { data } = src.bitmap;
const avg = (data[idx + 0]! + data[idx + 1]! + data[idx + 2]!) / 3;
image.bitmap.data[dstIdx + 3] *= avg / 255;
}
});
return image;
},
};
