//0.4  加入repaint畫面重畫機制  使用雙緩沖使得畫面更流暢
//0.5  加入兩個常量，用于分辨率更改容易些；
//0.6  加入鍵盤監聽類，使坦克隨鍵盤動起來，四個方向
import java.awt.*;
import java.awt.event.*;


public class TankClient extends Frame{
	
	public static final int GAME_WEIGHT = 800;
	public static final int GAME_HEIGHT = 600;
	
	int x = 50;
	int y = 50;
	Image offScreenImage = null;
	
	public void paint(Graphics g){
				
		Color c = g.getColor();
		g.setColor(Color.RED);
		g.fillOval(x, y, 30, 30);
		g.setColor(c);		
	}
	
	
	public void update(Graphics g) {
		if(offScreenImage == null){
			offScreenImage = this.createImage(GAME_WEIGHT, GAME_HEIGHT);
		}
		
		Graphics gOffScreenImage = offScreenImage.getGraphics();
		Color c = gOffScreenImage.getColor();
		gOffScreenImage.setColor(Color.WHITE);
		gOffScreenImage.fillRect(0, 0, GAME_WEIGHT, GAME_HEIGHT);
		paint(gOffScreenImage);
		g.drawImage(offScreenImage,0 ,0,null);
	
	}

	

	
	
	public void LauchFrame(){
			
		this.setLocation(400, 300);
		this.setSize(GAME_WEIGHT, GAME_HEIGHT);	
		this.setTitle("坦克大戰");
		this.setResizable(false);
		this.addKeyListener(new KeyMonitor());
		
		this.addWindowListener(new WindowAdapter(){
			public void windowClosing(WindowEvent e) {
				System.exit(0);
			}
		});
		this.setVisible(true);
		new Thread(new PaintThread()).start();
	}	
	
	public static void main(String[] args) {
	
		TankClient tc = new TankClient();
		tc.LauchFrame();
	
	}
	
	class PaintThread implements Runnable{

		public void run() {
			
			while(true){
				repaint();
				try {
					Thread.sleep(20);
				} catch (InterruptedException e) {
					e.printStackTrace();
				}
			}						
		}
		
		
		
	}

	class KeyMonitor extends KeyAdapter{

		public void keyPressed(KeyEvent e) {
			 int key = e.getKeyCode();
			switch(key){
			case KeyEvent.VK_UP:
				y -= 5;
			break;
			case KeyEvent.VK_RIGHT:
				x += 5;
			break;
			case KeyEvent.VK_DOWN:
				y += 5;
			break;
			case KeyEvent.VK_LEFT:
				x -= 5;
			break;
			}
		}		
	}
}