Move square and paint with Swing - Java Swing

Java examples for Swing:Mouse Event

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Description

Move square and paint with Swing

Demo Code

import javax.swing.SwingUtilities;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.BorderFactory;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseMotionListener;
import java.awt.event.MouseMotionAdapter;

public class SwingPaintDemo4 {

    public static void main(String[] args) {

        SwingUtilities.invokeLater(new Runnable() {
            public void run() {
                createAndShowGUI();/*from w  w w .  j a va 2 s .  c o  m*/
            }
        });
    }

    private static void createAndShowGUI() {
        System.out.println("Created GUI on EDT? "
                + SwingUtilities.isEventDispatchThread());
        JFrame f = new JFrame("Swing Paint Demo");
        f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        f.add(new MyPanel());
        f.setSize(250, 250);
        f.setVisible(true);
    }

}

class MyPanel extends JPanel {

    RedSquare redSquare = new RedSquare();

    public MyPanel() {

        setBorder(BorderFactory.createLineBorder(Color.black));

        addMouseListener(new MouseAdapter() {
            public void mousePressed(MouseEvent e) {
                moveSquare(e.getX(), e.getY());
            }
        });

        addMouseMotionListener(new MouseAdapter() {
            public void mouseDragged(MouseEvent e) {
                moveSquare(e.getX(), e.getY());
            }
        });

    }

    private void moveSquare(int x, int y) {

        // Current square state, stored as final variables 
        // to avoid repeat invocations of the same methods.
        final int CURR_X = redSquare.getX();
        final int CURR_Y = redSquare.getY();
        final int CURR_W = redSquare.getWidth();
        final int CURR_H = redSquare.getHeight();
        final int OFFSET = 1;

        if ((CURR_X != x) || (CURR_Y != y)) {

            // The square is moving, repaint background 
            // over the old square location. 
            repaint(CURR_X, CURR_Y, CURR_W + OFFSET, CURR_H + OFFSET);

            // Update coordinates.
            redSquare.setX(x);
            redSquare.setY(y);

            // Repaint the square at the new location.
            repaint(redSquare.getX(), redSquare.getY(),
                    redSquare.getWidth() + OFFSET, redSquare.getHeight()
                            + OFFSET);
        }
    }

    public Dimension getPreferredSize() {
        return new Dimension(250, 200);
    }

    public void paintComponent(Graphics g) {
        super.paintComponent(g);
        g.drawString("This is my custom Panel!", 10, 20);

        redSquare.paintSquare(g);
    }
}

class RedSquare {

    private int xPos = 50;
    private int yPos = 50;
    private int width = 20;
    private int height = 20;

    public void setX(int xPos) {
        this.xPos = xPos;
    }

    public int getX() {
        return xPos;
    }

    public void setY(int yPos) {
        this.yPos = yPos;
    }

    public int getY() {
        return yPos;
    }

    public int getWidth() {
        return width;
    }

    public int getHeight() {
        return height;
    }

    public void paintSquare(Graphics g) {
        g.setColor(Color.RED);
        g.fillRect(xPos, yPos, width, height);
        g.setColor(Color.BLACK);
        g.drawRect(xPos, yPos, width, height);
    }
}

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 *
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 * modification, are permitted provided that the following conditions
 * are met:
 *
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 *     notice, this list of conditions and the following disclaimer.
 *
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 *
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 *     from this software without specific prior written permission.
 *
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