Android使用SurfaceView画图

布局文件layout.xml

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity" >

    <SurfaceView
        android:id="@+id/surfaceview"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        />

</RelativeLayout>

Activity 代码如下：

package com.example.surfaceview;

import android.app.Activity;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Rect;
import android.os.Bundle;
import android.view.MotionEvent;
import android.view.SurfaceHolder;
import android.view.SurfaceHolder.Callback;
import android.view.SurfaceView;
import android.view.View;
import android.view.View.OnTouchListener;



public class MainActivity extends Activity {
    // SurfaceHolder负责维护SurfaceView上绘制的内容 
    private SurfaceHolder holder;
    private Paint paint;
  
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        paint = new Paint();
        // 获取SurfaceView实例 
        SurfaceView surface = (SurfaceView) findViewById(R.id.surfaceview);
        // 初始化SurfaceHolder对象 
        holder = surface.getHolder();
        holder.addCallback(new Callback() {
            //当surface将要被销毁时回调该方法 
            @Override
            public void surfaceDestroyed(SurfaceHolder holder) {
  
            }
            //当surface被创建时回调该方法 
            @Override
            public void surfaceCreated(SurfaceHolder holder) {
                // 锁定整个SurfaceView 
                Canvas canvas = holder.lockCanvas();
                // 获取背景资源 
                Bitmap bitmap = BitmapFactory.decodeResource(
                        MainActivity.this.getResources(),
                        R.drawable.test);
                // 绘制背景 
                canvas.drawBitmap(bitmap, 0, 0, null);
                // 绘制完成，释放画布，提交修改 
                holder.unlockCanvasAndPost(canvas);
                // 重新锁两次，避免下次lockCanvas遮挡 
                holder.lockCanvas(new Rect(0, 0, 0, 0));
                holder.unlockCanvasAndPost(canvas);
                holder.lockCanvas(new Rect(0, 0, 0, 0));
                holder.unlockCanvasAndPost(canvas);
            }
            //当一个surface的格式或大小发生改变时回调该方法 
            @Override
            public void surfaceChanged(SurfaceHolder holder, int format,
                    int width, int height) {
  
            }
        });
        surface.setOnTouchListener(new OnTouchListener() {
  
            @Override
            public boolean onTouch(View v, MotionEvent event) {
                // 只处理按下事件 
                if (event.getAction() == MotionEvent.ACTION_DOWN) {
                    int cx = (int) event.getX();
                    int cy = (int) event.getY();
                    System.out.println(cx+"==="+cy);
                    // 锁定SurfaceView的局部区域，只更新局部内容 
                    
                    Canvas canvas = holder.lockCanvas(new Rect(cx - 60,
                            cy - 60, cx + 60, cy + 60));
                    // 保存canvas的当前状态 
                    canvas.save();
                    // 旋转画布 
              //      canvas.rotate(30, cx, cy);
                    paint.setColor(Color.RED);
                    paint.setAntiAlias(true);
                    canvas.drawCircle(cx, cy, 50, paint);
                    // 绘制红色方块 
                //    canvas.drawRect(cx - 40, cy - 40, cx, cy, paint);
                    // 恢复canvas之前的保存状态 
//                    canvas.restore();
//                    paint.setColor(Color.GREEN);
//                    // 绘制绿色方块 
//                    canvas.drawRect(cx, cy, cx + 40, cy + 40, paint);
                    // 绘制完成，释放画布，提交修改 
                    holder.unlockCanvasAndPost(canvas);
                }
                return false;
            }
        });
    }
  
}