Android canvas的save()和restore()用法

raymondlueng

在读Android SDK里面的samples里面游戏的时候，很多时候都看到对canvas的save()和restore()运用。
下面是个小程序，使用了这两个方面，使得旋转红色方块的时候，保证蓝色方块不受影响。
 
 
 
代码如下：
package com.ray.test;import android.app.Activity;import android.content.Context;import android.graphics.Canvas;import android.graphics.Color;import android.graphics.Paint;import android.os.Bundle;import android.view.SurfaceHolder;import android.view.SurfaceView;public class Test extends Activity {    /** Called when the activity is first created. */    @Override    public void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(new MyView(this));    }        class MyView extends SurfaceView implements SurfaceHolder.Callback{    private SurfaceHolder mHolder;    private Canvas canvas;public MyView(Context context) {super(context);mHolder = getHolder();mHolder.addCallback(this);}@Overridepublic void surfaceChanged(SurfaceHolder holder, int format, int width,int height) {}@Overridepublic void surfaceCreated(SurfaceHolder holder) {canvas = mHolder.lockCanvas();Paint mPaint = new Paint();mPaint.setColor(Color.BLUE);canvas.drawRect(100, 200, 200, 300, mPaint);canvas.save();canvas.rotate(45);mPaint.setColor(Color.RED);canvas.drawRect(150, 10, 200, 60, mPaint);canvas.restore();mHolder.unlockCanvasAndPost(canvas);}@Overridepublic void surfaceDestroyed(SurfaceHolder holder) {// TODO Auto-generated method stub}        }}