fix: correct hypothenuse implementation when custom channels are passed (#407)

Author: EscapedGibbon

src/filters/__tests__/hypotenuse.test.ts

@@ -41,3 +41,23 @@ test('different number of channels', () => {
     image.hypotenuse(otherImage);
   }).toThrow('both images must have the same number of channels');
 });
+
+test('testing with a custom channel', () => {
+  const image = testUtils.createRgbImage([[3, 5, 8]]);
+  const otherImage = testUtils.createRgbImage([[4, 12, 15]]);
+
+  const expected = testUtils.createRgbImage([[3, 13, 8]]);
+  expect(image.hypotenuse(otherImage, { channels: [1] })).toMatchImage(
+    expected,
+  );
+});
+
+test('testing with custom channels', () => {
+  const image = testUtils.createRgbaImage([[3, 5, 8, 0]]);
+  const otherImage = testUtils.createRgbaImage([[4, 12, 15, 0]]);
+
+  const expected = testUtils.createRgbaImage([[5, 13, 17, 0]]);
+  expect(image.hypotenuse(otherImage, { channels: [0, 1, 2] })).toMatchImage(
+    expected,
+  );
+});

src/filters/hypotenuse.ts

@@ -1,13 +1,9 @@
-import { BitDepth, Image } from '..';
+import { Image } from '..';
+import { getOutputImage } from '../utils/getOutputImage';
 import checkProcessable from '../utils/validators/checkProcessable';
 import { validateChannels } from '../utils/validators/validators';
 
 export interface HypotenuseOptions {
-  /**
-   * Bit depth of the resulting image.
-   * @default `image.bitDepth`
-   */
-  bitDepth?: BitDepth;
   /**
    * To which channels to apply the filter. By default all but alpha.
    */
@@ -26,11 +22,9 @@ export function hypotenuse(
   otherImage: Image,
   options: HypotenuseOptions = {},
 ): Image {
-  const { bitDepth = image.bitDepth, channels = [] } = options;
-
-  for (let i = 0; i < image.components; i++) {
-    channels.push(i);
-  }
+  const {
+    channels = new Array(image.components).fill(0).map((value, index) => index),
+  } = options;
 
   checkProcessable(image, {
     bitDepth: [8, 16],
@@ -51,14 +45,15 @@ export function hypotenuse(
 
   validateChannels(channels, image);
 
-  const newImage = Image.createFrom(image, { bitDepth });
+  const newImage = getOutputImage(image, {}, { clone: true });
 
   for (const channel of channels) {
     for (let i = 0; i < image.size; i++) {
       const value = Math.hypot(
         image.getValueByIndex(i, channel),
         otherImage.getValueByIndex(i, channel),
       );
+
       newImage.setValueByIndex(
         i,
         channel,