initial commit

samples/java/tutorial_code/ShapeDescriptors/hull/HullDemo.java

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+import java.awt.BorderLayout;
+import java.awt.Container;
+import java.awt.Image;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Random;
+
+import javax.swing.BoxLayout;
+import javax.swing.ImageIcon;
+import javax.swing.JFrame;
+import javax.swing.JLabel;
+import javax.swing.JPanel;
+import javax.swing.JSlider;
+import javax.swing.event.ChangeEvent;
+import javax.swing.event.ChangeListener;
+
+import org.opencv.core.Core;
+import org.opencv.core.CvType;
+import org.opencv.core.Mat;
+import org.opencv.core.MatOfInt;
+import org.opencv.core.MatOfPoint;
+import org.opencv.core.Point;
+import org.opencv.core.Scalar;
+import org.opencv.core.Size;
+import org.opencv.highgui.HighGui;
+import org.opencv.imgcodecs.Imgcodecs;
+import org.opencv.imgproc.Imgproc;
+
+class Hull {
+    private Mat srcGray = new Mat();
+    private JFrame frame;
+    private JLabel imgSrcLabel;
+    private JLabel imgContoursLabel;
+    private static final int MAX_THRESHOLD = 255;
+    private int threshold = 100;
+    private Random rng = new Random(12345);
+
+    public Hull(String[] args) {
+        /// Load source image
+        String filename = args.length > 0 ? args[0] : "../data/stuff.jpg";
+        Mat src = Imgcodecs.imread(filename);
+        if (src.empty()) {
+            System.err.println("Cannot read image: " + filename);
+            System.exit(0);
+        }
+
+        /// Convert image to gray and blur it
+        Imgproc.cvtColor(src, srcGray, Imgproc.COLOR_BGR2GRAY);
+        Imgproc.blur(srcGray, srcGray, new Size(3, 3));
+
+        // Create and set up the window.
+        frame = new JFrame("Convex Hull demo");
+        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
+        // Set up the content pane.
+        Image img = HighGui.toBufferedImage(src);
+        addComponentsToPane(frame.getContentPane(), img);
+        // Use the content pane's default BorderLayout. No need for
+        // setLayout(new BorderLayout());
+        // Display the window.
+        frame.pack();
+        frame.setVisible(true);
+        update();
+    }
+
+    private void addComponentsToPane(Container pane, Image img) {
+        if (!(pane.getLayout() instanceof BorderLayout)) {
+            pane.add(new JLabel("Container doesn't use BorderLayout!"));
+            return;
+        }
+
+        JPanel sliderPanel = new JPanel();
+        sliderPanel.setLayout(new BoxLayout(sliderPanel, BoxLayout.PAGE_AXIS));
+
+        sliderPanel.add(new JLabel("Canny threshold: "));
+        JSlider slider = new JSlider(0, MAX_THRESHOLD, threshold);
+        slider.setMajorTickSpacing(20);
+        slider.setMinorTickSpacing(10);
+        slider.setPaintTicks(true);
+        slider.setPaintLabels(true);
+        slider.addChangeListener(new ChangeListener() {
+            @Override
+            public void stateChanged(ChangeEvent e) {
+                JSlider source = (JSlider) e.getSource();
+                threshold = source.getValue();
+                update();
+            }
+        });
+        sliderPanel.add(slider);
+        pane.add(sliderPanel, BorderLayout.PAGE_START);
+
+        JPanel imgPanel = new JPanel();
+        imgSrcLabel = new JLabel(new ImageIcon(img));
+        imgPanel.add(imgSrcLabel);
+
+        Mat blackImg = Mat.zeros(srcGray.size(), CvType.CV_8U);
+        imgContoursLabel = new JLabel(new ImageIcon(HighGui.toBufferedImage(blackImg)));
+        imgPanel.add(imgContoursLabel);
+
+        pane.add(imgPanel, BorderLayout.CENTER);
+    }
+
+    private void update() {
+        /// Detect edges using Canny
+        Mat cannyOutput = new Mat();
+        Imgproc.Canny(srcGray, cannyOutput, threshold, threshold * 2);
+
+        /// Find contours
+        List<MatOfPoint> contours = new ArrayList<>();
+        Mat hierarchy = new Mat();
+        Imgproc.findContours(cannyOutput, contours, hierarchy, Imgproc.RETR_TREE, Imgproc.CHAIN_APPROX_SIMPLE);
+
+        /// Find the convex hull object for each contour
+        List<MatOfPoint> hullList = new ArrayList<>();
+        for (MatOfPoint contour : contours) {
+            MatOfInt hull = new MatOfInt();
+            Imgproc.convexHull(contour, hull);
+
+            Point[] contourArray = contour.toArray();
+            Point[] hullPoints = new Point[hull.rows()];
+            List<Integer> hullContourIdxList = hull.toList();
+            for (int i = 0; i < hullContourIdxList.size(); i++) {
+                hullPoints[i] = contourArray[hullContourIdxList.get(i)];
+            }
+            hullList.add(new MatOfPoint(hullPoints));
+        }
+
+        /// Draw contours + hull results
+        Mat drawing = Mat.zeros(cannyOutput.size(), CvType.CV_8UC3);
+        for (int i = 0; i < contours.size(); i++) {
+            Scalar color = new Scalar(rng.nextInt(256), rng.nextInt(256), rng.nextInt(256));
+            Imgproc.drawContours(drawing, contours, i, color);
+            Imgproc.drawContours(drawing, hullList, i, color );
+        }
+
+        imgContoursLabel.setIcon(new ImageIcon(HighGui.toBufferedImage(drawing)));
+        frame.repaint();
+    }
+}
+
+public class HullDemo {
+    public static void main(String[] args) {
+        // Load the native OpenCV library
+        System.loadLibrary(Core.NATIVE_LIBRARY_NAME);
+
+        // Schedule a job for the event dispatch thread:
+        // creating and showing this application's GUI.
+        javax.swing.SwingUtilities.invokeLater(new Runnable() {
+            @Override
+            public void run() {
+                new Hull(args);
+            }
+        });
+    }
+}