Android在SurfaceView绘图

MainActivity

package com.example.surfacedemo;

import android.os.Bundle;
import android.app.Activity;
import android.view.Menu;

public class MainActivity extends Activity {

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(new MyView(this)); //设置显示MyView实例
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        getMenuInflater().inflate(R.menu.activity_main, menu);
        return true;
    }    
}

MyView

package com.example.surfacedemo;

import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.view.SurfaceHolder;
import android.view.SurfaceHolder.Callback;
import android.view.SurfaceView;

public class MyView extends SurfaceView {
    
    SurfaceHolder sh;

    public MyView(Context context) {
        super(context);
        sh = getHolder();//得到Holder
        sh.addCallback(new Callback() {//创建回调
            
            public void surfaceDestroyed(SurfaceHolder holder) {//界面销毁时执行
                
            }
            
            public void surfaceCreated(SurfaceHolder holder) {//界面创建后执行
                Canvas canvas = sh.lockCanvas();
                Paint paint=new Paint();
                paint.setColor(Color.BLUE);
                canvas.drawCircle(100,100, 20, paint);
                sh.unlockCanvasAndPost(canvas);
            }
            
            public void surfaceChanged(SurfaceHolder holder, int format, int width,
                    int height) {//界面改变时执行
                
            }
        });
    }

}