Created data-sink interface + image-writer implementation

Author: s1hofmann

lib/provider/opencv/data-sink.interface.ts

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+/**
+ * A DataSink should provide methods to store data
+ *
+ * @interface DataSink
+ */
+export interface DataSink {
+  /**
+   * store will write data to disk
+   * @param data Data to write
+   * @param path Absolute output file path
+   */
+  store(data: any, path: string): Promise<any>;
+}

lib/provider/opencv/image-writer.class.spec.ts

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+import { existsSync, unlinkSync } from "fs";
+import { resolve } from "path";
+import { ImageReader } from "./image-reader.class";
+import { ImageWriter } from "./image-writer.class";
+
+const INPUT_PATH = resolve(__dirname, "./__mocks__/mouse.png");
+const OUTPUT_PATH_PNG = resolve(__dirname, "./__mocks__/output.png");
+const OUTPUT_PATH_JPG = resolve(__dirname, "./__mocks__/output.jpg");
+
+beforeEach(() => {
+  for (const file of [OUTPUT_PATH_JPG, OUTPUT_PATH_PNG]) {
+    if (existsSync(file)) {
+      unlinkSync(file);
+    }
+  }
+});
+
+describe.each([[OUTPUT_PATH_PNG], [OUTPUT_PATH_JPG]])(
+  "Image writer", (outputPath) => {
+    test("should allow to store image data to disk", async () => {
+      // GIVEN
+      const imageReader = new ImageReader();
+      const image = await imageReader.load(INPUT_PATH);
+      const imageWriter = new ImageWriter();
+
+      // WHEN
+      await imageWriter.store(image, outputPath);
+
+      // THEN
+      expect(existsSync(outputPath)).toBeTruthy();
+    });
+  });

lib/provider/opencv/image-writer.class.ts

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+import * as cv from "opencv4nodejs";
+import { Image } from "../../image.class";
+import { DataSink } from "./data-sink.interface";
+import { ImageProcessor } from "./image-processor.class";
+
+export class ImageWriter implements DataSink {
+  public async store(data: Image, path: string): Promise<void> {
+    let outputMat: cv.Mat;
+    if (data.hasAlphaChannel) {
+      outputMat = await ImageProcessor.fromImageWithAlphaChannel(data);
+    } else {
+      outputMat = await ImageProcessor.fromImageWithoutAlphaChannel(data);
+    }
+    return cv.imwriteAsync(path, outputMat);
+  }
+}