How to draw a filled polygon in OpenCV using Java?

The org.opencv.imgproc package of Java OpenCV library contains a class named Imgproc. To draw a filled polygon you need to invoke the fillPoly() method of this class. This method accepts the following parameters −

  • A Mat object representing the image on which the polygon is to be drawn.

  • A-List object holding the objects of the type MatOfPoint.

  • A Scalar object representing the color of the polygon.

  • An integer representing the line type.


import java.util.ArrayList;
import java.util.List;
import org.opencv.core.Core;
import org.opencv.core.Mat;
import org.opencv.core.MatOfPoint;
import org.opencv.core.Point;
import org.opencv.core.Scalar;
import org.opencv.highgui.HighGui;
import org.opencv.imgcodecs.Imgcodecs;
import org.opencv.imgproc.Imgproc;
public class DrawingFilledPolygon {
   public static void main(String args[]) {
      //Loading the OpenCV core library
      System.loadLibrary( Core.NATIVE_LIBRARY_NAME );
      //Loading the OpenCV core library
      System.loadLibrary( Core.NATIVE_LIBRARY_NAME );
      //Reading the source image in to a Mat object
      Mat src = Imgcodecs.imread("D:\images\blank.jpg");
      //Drawing a polygon
      List<MatOfPoint>list = new ArrayList<MatOfPoint>();
         list.add(new MatOfPoint (
         new Point(208, 71), new Point(421, 161),
         new Point(332, 52), new Point(369, 250),
         new Point(421, 161), new Point(226, 232),
         new Point(369, 250), new Point(208, 71),
         new Point(226, 232), new Point(332, 52)));
      Scalar color = new Scalar(64, 64, 64);
      int lineType = Imgproc.LINE_8;
      Imgproc.fillPoly(src, list, color, lineType);
      //Saving and displaying the image
      Imgcodecs.imwrite("arrowed_line.jpg", src);
      HighGui.imshow("Drawing a polygon", src);


On executing, the above program generates the following window −