(#68) Moved matching of images to separate function

Author: s1hofmann

lib/provider/opencv/match-image.function.spec.ts

@@ -0,0 +1,41 @@
+import * as cv from "opencv4nodejs-prebuilt";
+import { mockPartial } from "sneer";
+import { matchImages } from "./match-image.function";
+
+describe("matchImages", () => {
+  it("should return minLoc position and needle size", async () => {
+    // GIVEN
+    const minLocX = 100;
+    const minLocY = 1000;
+    const matchMock = mockPartial<cv.Mat>({
+      minMaxLocAsync: jest.fn(() => Promise.resolve({
+        maxLoc: new cv.Point2(
+          200,
+          2000
+        ),
+        maxVal: 100,
+        minLoc: new cv.Point2(
+          minLocX,
+          minLocY
+        ),
+        minVal: 0,
+      }))
+    });
+    const haystackMock = mockPartial<cv.Mat>({
+      matchTemplateAsync: jest.fn(() => Promise.resolve(matchMock))
+    });
+    const needleMock = mockPartial<cv.Mat>({
+      cols: 123,
+      rows: 456
+    });
+
+    // WHEN
+    const result = await matchImages(haystackMock, needleMock);
+
+    // THEN
+    expect(result.location.left).toEqual(minLocX);
+    expect(result.location.top).toEqual(minLocY);
+    expect(result.location.width).toEqual(needleMock.cols);
+    expect(result.location.height).toEqual(needleMock.rows);
+  });
+});

lib/provider/opencv/match-image.function.ts

@@ -0,0 +1,20 @@
+import * as cv from "opencv4nodejs-prebuilt";
+import { MatchResult } from "../../match-result.class";
+import { Region } from "../../region.class";
+
+export const matchImages = async (haystack: cv.Mat, needle: cv.Mat): Promise<MatchResult> => {
+  const match = await haystack.matchTemplateAsync(
+    needle,
+    cv.TM_SQDIFF_NORMED,
+  );
+  const minMax = await match.minMaxLocAsync();
+  return new MatchResult(
+    1.0 - minMax.minVal,
+    new Region(
+      minMax.minLoc.x,
+      minMax.minLoc.y,
+      needle.cols,
+      needle.rows,
+    ),
+  );
+};