feat: initial testgin for face detection

pom.xml

@@ -21,6 +21,11 @@
   </properties>
 
   <dependencies>
+    <dependency>
+      <groupId>org.openpnp</groupId>
+      <artifactId>opencv</artifactId>
+      <version>4.9.0-0</version>
+    </dependency>
     <dependency>
       <groupId>org.junit.jupiter</groupId>
       <artifactId>junit-jupiter</artifactId>

src/test/java/com/example/facetracker/AppTest.java

@@ -1,7 +1,19 @@
 package com.example.facetracker;
 
-import org.junit.jupiter.api.Test;
+
 import static org.junit.jupiter.api.Assertions.assertTrue;
+import org.junit.jupiter.api.Test;
+import org.opencv.core.Mat;
+import org.opencv.core.MatOfRect;
+import org.opencv.core.Rect;
+import org.opencv.core.Scalar;
+import org.opencv.core.Size;
+import org.opencv.imgcodecs.Imgcodecs;
+import org.opencv.imgproc.Imgproc;
+import org.opencv.objdetect.CascadeClassifier;
+import org.opencv.objdetect.Objdetect;
+
+import nu.pattern.OpenCV;
 
 /**
  * Unit test for simple App.
@@ -15,4 +27,41 @@ public class AppTest {
     public void testApp() {
         assertTrue(true);
     }
+
+    private static class Tracker {
+        private CascadeClassifier faceCascade;
+
+        public Tracker() {
+            faceCascade = new CascadeClassifier();
+            faceCascade.load("src/test/resources/haarcascade_frontalface_alt.xml");
+        }
+
+        public Rect[] detect(Mat img) {
+            MatOfRect faces = new MatOfRect();
+            long min = Math.round(0.1 * img.width());
+            faceCascade.detectMultiScale(img, faces, 1.1, 3, Objdetect.CASCADE_SCALE_IMAGE, new Size(min, min));
+            return faces.toArray();
+        }
+    }
+
+    @Test
+    public void testImage() {
+        OpenCV.loadLocally();
+        Tracker tracker = new Tracker();
+        Mat img = Imgcodecs.imread("src/test/resources/20250809_151039_preview.jpeg");
+        Rect[] facesArray = tracker.detect(img);
+        for (Rect face : facesArray) {
+            Imgproc.rectangle(img, face, new Scalar(0, 255, 0), 2);
+        }
+        Imgcodecs.imwrite("out.jpg", img);
+    }
+
+    /*
+    @Test
+    public void testVideo() {
+        OpenCV.loadLocally();
+        VideoCapture videoCapture = new VideoCapture("src/test/resources/20250718_205627.mp4");
+        VideoWriter writer = new VideoWriter("out.mp4", VideoWriter.fourcc('M', 'P', '4', 'V'), 30, new Size(640, 480));
+
+    } */
 }