Desktop : OpenCV Change Size Use Get Rotation Matrix2D

<H5>Goal</h5>
Test OpenCV Change Size Use Get Rotation Matrix2D.

```OpenCV_ChangeSizeUseGetRotationMatrix2D.java
import java.awt.EventQueue;
import javax.swing.ImageIcon;
import javax.swing.JFrame;
import javax.swing.JLabel;
import java.awt.image.BufferedImage;
import org.opencv.core.Core;
import org.opencv.core.CvType;
import org.opencv.core.Mat;
import org.opencv.core.Point;
import org.opencv.imgcodecs.Imgcodecs;
import org.opencv.imgproc.Imgproc;
import javax.swing.JButton;
import java.awt.event.ActionListener;
import java.awt.event.ActionEvent;
import javax.swing.JSlider;
import javax.swing.event.ChangeListener;
import javax.swing.event.ChangeEvent;

public class OpenCV_ChangeSizeUseGetRotationMatrix2D {

    static{System.loadLibrary(Core.NATIVE_LIBRARY_NAME);}
    private Mat src  = new Mat();
    private JFrame frmjavaSwing;

    /**
     *  Launcher the application.
     */
    public static void main(String[] args){

        EventQueue.invokeLater(new Runnable() {
            @Override
            public void run() {
               try{
                   OpenCV_ChangeSizeUseGetRotationMatrix2D window = new OpenCV_ChangeSizeUseGetRotationMatrix2D();
                   window.frmjavaSwing.setVisible(true);
               }catch (Exception e){
                   e.printStackTrace();
               }
            }
        });
    }

    /**
     *  Create the application.
     */
    public OpenCV_ChangeSizeUseGetRotationMatrix2D(){
        initialize();
    }

    /**
     *  Init the contents of the frame.
     */
    private void initialize() {
        final Mat src = Imgcodecs.imread("C://opencv3.1//samples//lena.jpg");
        setSource(src);
        BufferedImage image=matToBufferedImage(src);

        frmjavaSwing = new JFrame();
        frmjavaSwing.setTitle("opencv 放大縮小練習,使用getRotationMatrix2D");
        frmjavaSwing.setBounds(100, 100, 520, 550);
        frmjavaSwing.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frmjavaSwing.getContentPane().setLayout(null);

        final JLabel lblNewLabel = new JLabel("");
        lblNewLabel.setBounds(10, 68, 438, 438);
        lblNewLabel.setIcon(new ImageIcon(image));
        frmjavaSwing.getContentPane().add(lblNewLabel);

        	JButton btnNewButton = new JButton("放大2倍");

        btnNewButton.setBounds(10, 21, 87, 23);
        frmjavaSwing.getContentPane().add(btnNewButton);

        	JButton button = new JButton("縮小2倍");

        button.setBounds(107, 21, 87, 23);
        frmjavaSwing.getContentPane().add(button);


        button.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent arg0) {
                BufferedImage newImage=matToBufferedImage( resize(getSource(),0.5));
                lblNewLabel.setIcon(new ImageIcon(newImage));
            }
        });
        btnNewButton.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent arg0) {
                BufferedImage newImage=matToBufferedImage( resize(getSource(),2));
                lblNewLabel.setIcon(new ImageIcon(newImage));
            }
        });
    }

    public Mat resize(Mat source,double size ){
        Mat rotMat=new Mat(2,3, CvType.CV_32FC1);
        Mat destination=new Mat(source.rows()*(int)size,source.cols()*(int)size,source.type());

        Point center=new Point(source.rows()/2,source.cols()/2);
        double angle=0;
        rotMat= Imgproc.getRotationMatrix2D(center, angle, size);
        Imgproc.warpAffine(source,destination, rotMat, destination.size());
        setSource(destination);
        return destination;

    }

    public BufferedImage matToBufferedImage(Mat matrix) {
        int cols = matrix.cols();
        int rows = matrix.rows();
        int elemSize = (int)matrix.elemSize();
        byte[] data = new byte[cols * rows * elemSize];
        int type;
        matrix.get(0, 0, data);
        switch (matrix.channels()) {
            case 1:
                type = BufferedImage.TYPE_BYTE_GRAY;
                break;
            case 3:
                type = BufferedImage.TYPE_3BYTE_BGR;
                // bgr to rgb
                byte b;
                for(int i=0; i<data.length; i=i+3) {
                    b = data[i];
                    data[i] = data[i+2];
                    data[i+2] = b;
                }
                break;
            default:
                return null;
        }
        BufferedImage image2 = new BufferedImage(cols, rows, type);
        image2.getRaster().setDataElements(0, 0, cols, rows, data);
        return image2;
    }

    public Mat getSource() {
        return src;
    }

    public void setSource(Mat source) {
        this.src = source;
    }
}
```
<h5>Result</h5>
![opencv_change_size_use_get_rotation_matrix2d.JPG](https://qiita-image-store.s3.ap-northeast-1.amazonaws.com/0/276243/aa69a4e9-aca9-fa56-fe06-cffaab85ccac.jpeg)