(#336) Extended Image class with color mode conversion methods

Author: s1hofmann

lib/image.class.spec.ts

@@ -1,30 +1,68 @@
-import { Image } from "./image.class";
+import {Image} from "./image.class";
+import {imageToJimp} from "./provider/io/imageToJimp.function";
+import {ColorMode} from "./colormode.enum";
+
+jest.mock("./provider/io/imageToJimp.function", () => {
+    return {
+        imageToJimp: jest.fn()
+    }
+});
+
+afterEach(() => {
+    jest.resetAllMocks();
+});
 
 describe("Image class", () => {
-  it("should return alphachannel = true for > 3 channels", () => {
-    const SUT = new Image(200, 200, 123, 4, "id");
-    expect(SUT.hasAlphaChannel).toBeTruthy();
-  });
-
-  it("should return alphachannel = false for <= 3 channels", () => {
-    const SUT = new Image(200, 200, 123, 3, "id");
-    expect(SUT.hasAlphaChannel).toBeFalsy();
-  });
-  it("should return alphachannel = false for <= 3 channels", () => {
-    const SUT = new Image(200, 200, 123, 2, "id");
-    expect(SUT.hasAlphaChannel).toBeFalsy();
-  });
-  it("should return alphachannel = false for <= 3 channels", () => {
-    const SUT = new Image(200, 200, 123, 1, "id");
-    expect(SUT.hasAlphaChannel).toBeFalsy();
-  });
-
-  it("should throw for <= 0 channels", () => {
-    expect(() => new Image(200, 200, 123, 0, "id")).toThrowError("Channel <= 0");
-  });
-
-  it("should have a default pixel density of 1.0", () => {
-    const SUT = new Image(200, 200, 123, 1, "id");
-    expect(SUT.pixelDensity).toEqual({ scaleX: 1.0, scaleY: 1.0 });
-  });
+    it("should return alphachannel = true for > 3 channels", () => {
+        const SUT = new Image(200, 200, 123, 4, "id");
+        expect(SUT.hasAlphaChannel).toBeTruthy();
+    });
+
+    it("should return alphachannel = false for <= 3 channels", () => {
+        const SUT = new Image(200, 200, 123, 3, "id");
+        expect(SUT.hasAlphaChannel).toBeFalsy();
+    });
+    it("should return alphachannel = false for <= 3 channels", () => {
+        const SUT = new Image(200, 200, 123, 2, "id");
+        expect(SUT.hasAlphaChannel).toBeFalsy();
+    });
+    it("should return alphachannel = false for <= 3 channels", () => {
+        const SUT = new Image(200, 200, 123, 1, "id");
+        expect(SUT.hasAlphaChannel).toBeFalsy();
+    });
+
+    it("should throw for <= 0 channels", () => {
+        expect(() => new Image(200, 200, 123, 0, "id")).toThrowError("Channel <= 0");
+    });
+
+    it("should have a default pixel density of 1.0", () => {
+        const SUT = new Image(200, 200, 123, 1, "id");
+        expect(SUT.pixelDensity).toEqual({scaleX: 1.0, scaleY: 1.0});
+    });
+
+    describe("Colormode", () => {
+        it("should not try to convert an image to BGR if it already has the correct color mode", async () => {
+            // GIVEN
+            const bgrImage = new Image(100, 100, Buffer.from([]), 3, "testImage");
+
+            // WHEN
+            const convertedImage = await bgrImage.toBGR();
+
+            // THEN
+            expect(convertedImage).toBe(bgrImage);
+            expect(imageToJimp).not.toBeCalledTimes(1)
+        });
+
+        it("should not try to convert an image to RGB if it already has the correct color mode", async () => {
+            // GIVEN
+            const rgbImage = new Image(100, 100, Buffer.from([]), 3, "testImage", ColorMode.RGB);
+
+            // WHEN
+            const convertedImage = await rgbImage.toRGB();
+
+            // THEN
+            expect(convertedImage).toBe(rgbImage);
+            expect(imageToJimp).not.toBeCalledTimes(1)
+        });
+    });
 });

lib/image.class.ts

@@ -1,3 +1,6 @@
+import {imageToJimp} from "./provider/io/imageToJimp.function";
+import {ColorMode} from "./colormode.enum";
+
 /**
  * The {@link Image} class represents generic image data
  */
@@ -9,6 +12,7 @@ export class Image {
      * @param data Generic {@link Image} data
      * @param channels Amount of {@link Image} channels
      * @param id Image identifier
+     * @param colorMode An images color mode, defaults to {@link ColorMode.BGR}
      * @param pixelDensity Object containing scale info to work with e.g. Retina display data where the reported display size and pixel size differ (Default: {scaleX: 1.0, scaleY: 1.0})
      */
     constructor(
@@ -17,6 +21,7 @@ export class Image {
         public readonly data: any,
         public readonly channels: number,
         public readonly id: string,
+        public readonly colorMode: ColorMode = ColorMode.BGR,
         public readonly pixelDensity: { scaleX: number; scaleY: number } = {
             scaleX: 1.0,
             scaleY: 1.0,
@@ -33,4 +38,35 @@ export class Image {
     public get hasAlphaChannel() {
         return this.channels > 3;
     }
+
+    /**
+     * {@link toRGB} converts an {@link Image} from BGR color mode (default within nut.js) to RGB
+     */
+    public async toRGB(): Promise<Image> {
+        if (this.colorMode === ColorMode.RGB) {
+            return this;
+        }
+        const rgbImage = imageToJimp(this);
+        return new Image(this.width, this.height, rgbImage.bitmap.data, this.channels, this.id, ColorMode.RGB, this.pixelDensity);
+    }
+
+    /**
+     * {@link toBGR} converts an {@link Image} from RGB color mode to RGB
+     */
+    public async toBGR(): Promise<Image> {
+        if (this.colorMode === ColorMode.BGR) {
+            return this;
+        }
+        const rgbImage = imageToJimp(this);
+        return new Image(this.width, this.height, rgbImage.bitmap.data, this.channels, this.id, ColorMode.BGR, this.pixelDensity);
+    }
+
+    /**
+     * {@link fromRGBData} creates an {@link Image} from provided RGB data
+     */
+    public static fromRGBData(width: number, height: number, data: Buffer, channels: number, id: string): Image {
+        const rgbImage = new Image(width, height, data, channels, id);
+        const jimpImage = imageToJimp(rgbImage);
+        return new Image(width, height, jimpImage.bitmap.data, channels, id);
+    }
 }