feat: implement channelLabels (#294)

* feat: implement channelLabels

Closes: #256

* Update src/utils/constants/channelLabels.ts

Co-authored-by: Michaël Zasso <[email protected]>

* fix: type error

---------

Co-authored-by: Michaël Zasso <[email protected]>

Author: opatiny

src/utils/constants/__tests__/channelLabels.test.ts

@@ -0,0 +1,42 @@
+import { Image } from '../../../Image';
+import { channelLabels } from '../channelLabels';
+import { ImageColorModel } from '../colorModels';
+
+test.each([
+  {
+    message: 'grey',
+    colorModel: ImageColorModel.GREY,
+    expected: ['Grey'],
+  },
+  {
+    message: 'greya',
+    colorModel: ImageColorModel.GREYA,
+    expected: ['Grey', 'Alpha'],
+  },
+  {
+    message: 'rgb',
+    colorModel: ImageColorModel.RGB,
+    expected: ['Red', 'Green', 'Blue'],
+  },
+  {
+    message: 'rgba',
+    colorModel: ImageColorModel.RGBA,
+    expected: ['Red', 'Green', 'Blue', 'Alpha'],
+  },
+  {
+    message: 'binary',
+    colorModel: ImageColorModel.BINARY,
+    expected: ['Mask'],
+  },
+])('channelLabels for $message image', (data) => {
+  expect(channelLabels[data.colorModel]).toStrictEqual(data.expected);
+});
+
+test('channelLabels through image colorModel', () => {
+  const image = new Image(2, 2);
+  expect(channelLabels[image.colorModel]).toStrictEqual([
+    'Red',
+    'Green',
+    'Blue',
+  ]);
+});

src/utils/constants/channelLabels.ts

@@ -0,0 +1,9 @@
+import { ImageColorModel } from './colorModels';
+
+export const channelLabels = {
+  GREY: ['Grey'],
+  GREYA: ['Grey', 'Alpha'],
+  RGB: ['Red', 'Green', 'Blue'],
+  RGBA: ['Red', 'Green', 'Blue', 'Alpha'],
+  BINARY: ['Mask'],
+} as const satisfies Record<ImageColorModel, readonly string[]>;