java 画图的问题！

[lwtprogress]

我想利用java画一个棋盘格，完成了，但是测试的时候有点不够满意。就是我是在paint（）方法中画的，每次更新都会有repaint（）。这时候会重复调用paint方法，也就是棋盘要被画很多遍，虽然图像不会改变，感觉很别扭。有没有方法可以只画一次棋盘。

[lwtprogress]

当然要求棋盘式始终显示的！！

[无水杯]

路过，，想法很好，打算用java2D来做么？

[niulei190922]

以下是绘制表盘的代码 2D做的：

import java.awt.geom.Ellipse2D;
import java.awt.geom.Line2D;
import java.util.Date;

import javax.swing.JFrame;
import javax.swing.JPanel;

public class TimeDemo extends JFrame{
private JPanel pan;
private double r1=160,r2=165,rm1=158,rm2=167,hr=100,mr=130,sr=167;
public TimeDemo(){
super("Time demo");
this.setBounds(200,200,410,430);
getMinLab();

pan=new MyPanel();
this.add(pan);

this.setVisible(true);
this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

MyThread th=new MyThread();
th.setDaemon(true);
th.start();

}

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

class MyPanel extends JPanel{
public void paint(Graphics g){
g.clearRect(0,0,this.getWidth(),this.getHeight());
Graphics2D g2=(Graphics2D)g;

BasicStroke bs=null;

// String num[]={"1","2","3","4","5","6","7","8","9","10","11","12"};
// 打开抗锯齿
g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING,
RenderingHints.VALUE_ANTIALIAS_ON);
Line2D line[]=getMinLab();
for(int i=0;i<line.length;i++){
bs=new BasicStroke(2,BasicStroke.CAP_ROUND,BasicStroke.JOIN_ROUND);
g2.setStroke(bs);
if(i%5==0){
bs=new BasicStroke(4,BasicStroke.CAP_ROUND,BasicStroke.JOIN_ROUND);
g2.setStroke(bs);

}
g2.draw(line[i]);
}

//计算时针
Date date=new Date();
int s=date.getSeconds();

double m=date.getMinutes()+s/60.0;

double h=date.getHours()+m/60.0;
System.out.println(h);

double hy=Math.sin(Math.PI/6*(h%12-3))*hr+200;
double hx=Math.cos(Math.PI/6*(h%12-3))*hr+200;
bs=new BasicStroke(6,BasicStroke.CAP_ROUND,BasicStroke.JOIN_ROUND);
g2.setStroke(bs);
Line2D.Double hline=new Line2D.Double(200,200,hx,hy);
g2.draw(hline);
// 计算分针
double my=Math.sin(Math.PI/30*(m-15))*mr+200;
double mx=Math.cos(Math.PI/30*(m-15))*mr+200;
bs=new BasicStroke(4,BasicStroke.CAP_ROUND,BasicStroke.JOIN_ROUND);
g2.setStroke(bs);
Line2D.Double mline=new Line2D.Double(200,200,mx,my);
g2.draw(mline);
// 计算秒针
double sy=Math.sin(Math.PI/30*(s-15))*sr+200;
double sx=Math.cos(Math.PI/30*(s-15))*sr+200;
bs=new BasicStroke(2,BasicStroke.CAP_ROUND,BasicStroke.JOIN_ROUND);
g2.setStroke(bs);
Line2D.Double sline=new Line2D.Double(200,200,sx,sy);
g2.draw(sline);

//画表盘

Ellipse2D.Double el=new Ellipse2D.Double(10,10,380,380);
g2.draw(el);
}
}

public Line2D[] getMinLab(){
Line2D[] lineM=new Line2D[60];

for(int i=0;i<lineM.length;i++){
double x1,y1,x2,y2;
double b1 = Math.sin(Math.PI / 30 * i);
double b2 = Math.cos(Math.PI / 30 * i);
if (i % 5 != 0) {
y1 = b1 * r1 + 200;
y2 = b1 * r2 + 200;
x1 = b2 * r1 + 200;
x2 = b2 * r2 + 200;
} else {
y1 = b1 * rm1 + 200;
y2 = b1 * rm2 + 200;
x1 = b2 * rm1 + 200;
x2 = b2 * rm2 + 200;
}

lineM[i]=new Line2D.Double(x1,y1,x2,y2);


// System.out.println(i+"-------("+x1+","+y1+"),("+x2+","+y2+")");
}

return lineM;
}

class MyThread extends Thread{
public void run(){
while(true){
pan.repaint();
try {
this.sleep(1000);
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
}

// public void refresh(){
// pan.repaint();
// this.validate();
// }

}

[afunx]

建议楼主可以采用双缓冲技术，应用BufferedImage类，把要画的图像先放入这个类中，在从这个类读到画板上。我最近在看的一本JAVA游戏编程书采用的就是这种方法。

[wyang1991]

[Quote=引用 4 楼 afunx 的回复:]
建议楼主可以采用双缓冲技术，应用BufferedImage类，把要画的图像先放入这个类中，在从这个类读到画板上。我最近在看的一本JAVA游戏编程书采用的就是这种方法。
[/Quote]

这楼说得对！

[lwtprogress]

我想到到一个方法：设定一个flag=ture，当读完一遍之后就设为FALSE。在要只读一遍的图上加上if语句就ok。
谢谢大家，我有时间再看看各楼的观点吧！