With this tutorial we are going to see how to handle moving and re sizing events in a Java Desktop application. You might find this useful when you want to add rich mouse functionality to the application. For example it’s very cool to let the users resize a window using the mouse wheel.
In short in order to move and resize objects using mouse events, one has to perform the following steps:
- Create a class that extends
MouseAdapter - Override the
mousePressedmethod to customize the handling of that specific event. Now every time you press a button this method will be launched. - Use
MouseEvent.getX,MouseEvent.getYmethods to get the coordinates of the position the mouse pointer had when the mouse event occurred. - Override the
mouseDraggedmethod to customize the handling of that specific event. Now every time you drag an object, this method will be launched. - Use
MouseEvent.getX,MouseEvent.getYmethods to get the new coordinates of the dragged object. Then callrepaint()to repaint the object to the new position. - Create a class that implements
MouseWheelListener. - Override
mouseWheelMovedmethod to customize the handling of that specific event. Now every time the user uses the mouse wheel this method will fire up. You can then useMouseWheelEvent.WHEEL_UNIT_SCROLLto get the scroll units amount and resize the window accordingly.
Let’s see the code:
package com.javacodegeeks.snippets.desktop;
import java.awt.Color;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.RenderingHints;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.awt.event.MouseWheelEvent;
import java.awt.event.MouseWheelListener;
import java.awt.geom.Rectangle2D;
import javax.swing.JFrame;
import javax.swing.JPanel;
public class Resize extends JPanel {
private Rectangle2D.Float myRect = new Rectangle2D.Float(90, 90, 90, 90);
BindMouseMove movingAdapt = new BindMouseMove();
public Resize() {
addMouseMotionListener(movingAdapt);
addMouseListener(movingAdapt);
addMouseWheelListener(new ResizeHandler());
}
@Override
public void paint(Graphics graphics) {
super.paint(graphics);
Graphics2D graphics2d = (Graphics2D) graphics;
graphics2d.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
graphics2d.setRenderingHint(RenderingHints.KEY_TEXT_ANTIALIASING, RenderingHints.VALUE_TEXT_ANTIALIAS_ON);
graphics2d.setColor(new Color(0, 0, 200));
graphics2d.fill(myRect);
}
class BindMouseMove extends MouseAdapter {
private int x;
private int y;
@Override
public void mousePressed(MouseEvent event) {
x = event.getX();
y = event.getY();
}
@Override
public void mouseDragged(MouseEvent event) {
int dx = event.getX() - x;
int dy = event.getY() - y;
if (myRect.getBounds2D().contains(x, y)) {
myRect.x += dx;
myRect.y += dy;
repaint();
}
x += dx;
y += dy;
}
}
class ResizeHandler implements MouseWheelListener {
@Override
public void mouseWheelMoved(MouseWheelEvent e) {
int x = e.getX();
int y = e.getY();
if (e.getScrollType() == MouseWheelEvent.WHEEL_UNIT_SCROLL) {
if (myRect.getBounds2D().contains(x, y)) {
float amount = e.getWheelRotation() * 5f;
myRect.width += amount;
myRect.height += amount;
repaint();
}
}
}
}
public static void main(String[] args) {
JFrame jFrame = new JFrame("Moving and Scaling");
Resize resi = new Resize();
resi.setDoubleBuffered(true);
jFrame.add(resi);
jFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
jFrame.setSize(300, 300);
jFrame.setLocationRelativeTo(null);
jFrame.setVisible(true);
}
}
This was an example on how to move and resize objects using Mouse Events
