(#307) Implement image reader

Author: s1hofmann

Diff for: lib/provider/io/jimp-image-reader.class.spec.ts

@@ -0,0 +1,47 @@
+import ImageReader from "./jimp-image-reader.class";
+import {join} from "path";
+import {Image} from "../../image.class";
+
+describe('Jimp image reader', () => {
+    it('should return an Image object', async () => {
+        // GIVEN
+        const inputPath = join(__dirname, "__mocks__", "calculator.png");
+        const expectedData = {
+            width: 34,
+            height: 28,
+            data: expect.any(Buffer),
+            channels: 3,
+            pixelDensity: {
+                scaleX: 1,
+                scaleY: 1
+            }
+        }
+        const SUT = new ImageReader();
+
+        // WHEN
+        const result = await SUT.load(inputPath);
+
+        // THEN
+        expect(result).toBeInstanceOf(Image);
+        expect(result.width).toBe(expectedData.width);
+        expect(result.height).toBe(expectedData.height);
+        expect(result.data).toStrictEqual(expectedData.data);
+        expect(result.channels).toBe(expectedData.channels);
+        expect(result.pixelDensity).toStrictEqual(expectedData.pixelDensity);
+    });
+
+    it('should reject on loading failures', async () => {
+        // GIVEN
+        const inputPath = "/fails/to/load";
+        const expectedError = `Failed to load image from '${inputPath}'. Reason: Error: ENOENT: no such file or directory, open '${inputPath}'`;
+        const SUT = new ImageReader();
+
+        // WHEN
+        try {
+            await SUT.load(inputPath);
+        } catch (err) {
+            // THEN
+            expect(err).toBe(expectedError);
+        }
+    });
+});

Diff for: lib/provider/io/jimp-image-reader.class.ts

@@ -0,0 +1,19 @@
+import Jimp from 'jimp';
+import {ImageReader} from "../image-reader.type";
+import {Image} from "../../image.class";
+
+export default class implements ImageReader {
+    load(parameters: string): Promise<Image> {
+        return new Promise<Image>((resolve, reject) => {
+            Jimp.read(parameters)
+                .then(jimpImage => {
+                    resolve(new Image(
+                        jimpImage.bitmap.width,
+                        jimpImage.bitmap.height,
+                        jimpImage.bitmap.data,
+                        jimpImage.hasAlpha() ? 4 : 3
+                    ));
+                }).catch(err => reject(`Failed to load image from '${parameters}'. Reason: ${err}`));
+        })
+    }
+}