练手java GUI(二)

使用所谓双缓冲技术(只是听说过的)绘图：

 

package gui.test05;

import java.awt.Color;
import java.awt.Dimension;
import java.awt.Font;
import java.awt.Frame;
import java.awt.Graphics;
import java.awt.Image;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;

public class DrawLine1 extends Frame {
	private int orgX;
	private int orgY;
	private int endX;
	private int endY;
	private Image oimg = null;
	private Graphics og = null;

	public DrawLine1() {
		initDisplay();
		initData();
		
		addWindowListener(new WindowAdapter() {

			@Override
			public void windowClosing(WindowEvent e) {
				dispose();
				System.exit(0);
			}

		});

		this.addMouseListener(new MouseAdapter() {

			@Override
			public void mousePressed(MouseEvent e) {
				orgX = e.getX();
				orgY = e.getY();
			}

			@Override
			public void mouseReleased(MouseEvent e) {
				endX = e.getX();
				endY = e.getY();
				//用内存Image对象绘制
				og.setColor(Color.RED);
				og.setFont(new Font(null, Font.ITALIC | Font.BOLD, 12));
				og.drawString(orgX + "," + orgY, orgX, orgY);
				og.drawString(endX + "," + endY, endX, endY);
				og.drawLine(orgX, orgY, endX, endY);
				//通过重绘来画图
				repaint();
			}

		});
	}

	private void initDisplay() {
		this.setSize(400, 400);
		this.setTitle("DrawLine");
		this.setVisible(true);
		//因为用了Componet.createImage方法创建内存Image对象(双缓冲),
		//当组件重画时,是将内存中的Image对象在组件上画出,所以设置不可重改大小
		this.setResizable(false);
	}

	private void initData() {
		Dimension d = this.getSize();
		oimg = this.createImage(d.width, d.height);
		og = oimg.getGraphics();
	}

	@Override
	public void paint(Graphics g) {
		g.drawImage(oimg, 0, 0, this);
	}

	public static void main(String[] args) {
		new DrawLine1();
		
	}
}