feat: export flip method (#35)

Co-authored-by: Mathis Mensing <github@matmen.dev>

Author: requizm

ImageScript.d.ts

@@ -17,7 +17,7 @@ export class Image {
   * [Symbol.iterator](): void;
 
   * iterateWithColors(): Generator<[x: number, y: number, color: number], void, unknown>;
-  
+
   static rgbaToColor(r: number, g: number, b: number, a: number): number;
 
   static rgbToColor(r: number, g: number, b: number): number;
@@ -112,6 +112,8 @@ export class Image {
 
   rotate(angle: number, resize?: boolean): Image;
 
+  flip(direction: 'horizontal' | 'vertical'): Image;
+
   private __apply__(image: Image | Frame): Image | Frame;
 
   static gradient(colors: { [position: number]: number; }): ((position: number) => number);
@@ -162,7 +164,7 @@ export class Frame extends Image {
   get disposalMode(): number;
 
   set disposalMode(disposalMode: string|number);
-  
+
   toString(): string;
 
   static from(image: Image, duration?: number, xOffset?: number, yOffset?: number, disposalMode?: typeof Frame.DISPOSAL_KEEP | string): Frame;

ImageScript.js

@@ -829,6 +829,17 @@ class Image {
         return this.__apply__(out);
     }
 
+    /**
+     * Flips / mirrors the image horizontally or vertically
+     * @param {'horizontal' | 'vertical'} direction The direction to flip
+     */
+    flip(direction) {
+        const frame = new v2(this.width, this.height, this.bitmap).flip(direction);
+
+        this.bitmap.set(frame.u8);
+        return this;
+    }
+
     /**
      * @private
      * @param {Image|Frame} image

tests/flip.js

@@ -0,0 +1,36 @@
+const fs = require('fs').promises;
+const {Image} = require('../ImageScript');
+
+(async () => {
+    const input = await fs.readFile('./tests/targets/external.png');
+
+    {
+        const image = await Image.decode(input);
+        image.flip('horizontal');
+
+        const output = await image.encode(1, {creationTime: 0, software: ''});
+
+        if (process.env.OVERWRITE_TEST)
+            await fs.writeFile('./tests/targets/flip-horizontal.png', output);
+
+        const target = await fs.readFile('./tests/targets/flip-horizontal.png');
+
+        if (!Buffer.from(target).equals(Buffer.from(output)))
+            process.exit(1);
+    }
+
+    {
+        const image = await Image.decode(input);
+        image.flip('vertical');
+
+        const output = await image.encode(1, {creationTime: 0, software: ''});
+
+        if (process.env.OVERWRITE_TEST)
+            await fs.writeFile('./tests/targets/flip-vertical.png', output);
+
+        const target = await fs.readFile('./tests/targets/flip-vertical.png');
+
+        if (!Buffer.from(target).equals(Buffer.from(output)))
+            process.exit(1);
+    }
+})();