Java Graphics_10

package com.han;

import java.awt.BorderLayout;
import java.awt.Canvas;
import java.awt.Container;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Image;
import java.awt.Toolkit;
import java.net.URL;

import javax.swing.JFrame;
import javax.swing.JSlider;
import javax.swing.event.ChangeEvent;
import javax.swing.event.ChangeListener;

@SuppressWarnings("serial")
public class Graphics_10 extends JFrame {
	JSlider slider;
	Canvas canvas;

	public Graphics_10() {
		// TODO Auto-generated constructor stub
		Container container = getContentPane();
		slider = new JSlider();
		canvas = new MyCanvas();
		container.add(canvas, BorderLayout.CENTER);
		container.add(slider, BorderLayout.SOUTH);
		
		/* configure JSlider */
		slider.setMinimum(1);
		slider.setMaximum(1000);
		slider.setValue(100);
		slider.addChangeListener(new ChangeListener() {

			@Override
			public void stateChanged(ChangeEvent e) {
				// TODO Auto-generated method stub
				canvas.repaint(); // the variable referred in the inner-cached class must be "final"
			}
			
		});
	}

	
	/**
	 * Canvas 会闪烁，当其上的图像缩放时。
	 * @author HAN
	 *
	 */
	class MyCanvas extends Canvas {
		@Override
		public void paint(Graphics g) {
			int currentValue = slider.getValue();
			
			URL resource = Graphics_10.class.getResource("/images/Lighthouse.jpg");
			Image img = Toolkit.getDefaultToolkit().getImage(resource);
			int newWidth = img.getWidth(this) * currentValue / 100;
			int newHeight = img.getHeight(this) * currentValue / 100;
			g.drawImage(img, 0, 0, newWidth, newHeight, canvas);
		}
	}
	
	/**
	 * @param args
	 */
	public static void main(String[] args) {
		// TODO Auto-generated method stub
		Graphics_10 frame = new Graphics_10();
		frame.setTitle("图像缩放");
		frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
		Dimension d = Toolkit.getDefaultToolkit().getScreenSize();
		frame.setBounds(0, 0, d.width, d.height);
		frame.setVisible(true);
	}

}