整个过程:继承SurfaceView并实现SurfaceHolder.Callback接口 ----> SurfaceView.getHolder()获得SurfaceHolder对象 ---->SurfaceHolder.addCallback(callback)添加回调函数---->SurfaceHolder.lockCanvas()获得Canvas对象并锁定画布----> Canvas绘画 ---->SurfaceHolder.unlockCanvasAndPost(Canvas canvas)结束锁定画图,并提交改变,将图形显示。
关于SurfaceHolder:
这里用到了一个类SurfaceHolder,可以把它当成surface的控制器,用来操纵surface。处理它的Canvas上画的效果和动画,控制表面,大小,像素等。
几个需要注意的方法:
(1)、abstract void addCallback(SurfaceHolder.Callback callback);
// 给SurfaceView当前的持有者一个回调对象。
(2)、abstract Canvas lockCanvas();
// 锁定画布,一般在锁定后就可以通过其返回的画布对象Canvas,在其上面画图等操作了。
(3)、abstract Canvas lockCanvas(Rect dirty);
// 锁定画布的某个区域进行画图等..因为画完图后,会调用下面的unlockCanvasAndPost来改变显示内容。
// 相对部分内存要求比较高的游戏来说,可以不用重画dirty外的其它区域的像素,可以提高速度。
(4)、abstract void unlockCanvasAndPost(Canvas canvas);
// 结束锁定画图,并提交改变。
测试代码如下:
/* * Android开发之SurfaceView * SurfaceView01.java * Created on: 2011-8-25 * Author: blueeagle * Email: liujiaxiang@gmail.com */ package com.blueeagle; import android.app.Activity; import android.content.Context; import android.graphics.Canvas; import android.graphics.Color; import android.graphics.Paint; import android.graphics.Rect; import android.os.Bundle; import android.view.SurfaceHolder; import android.view.SurfaceView; public class SurfaceView01 extends Activity { /** Called when the activity is first created. */ @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(new MyView(this)); } //视图内部类 class MyView extends SurfaceView implements SurfaceHolder.Callback { private SurfaceHolder holder; private MyThread myThread; public MyView(Context context) { super(context); // TODO Auto-generated constructor stub holder = this.getHolder(); holder.addCallback(this); myThread = new MyThread(holder);//创建一个绘图线程 } @Override public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) { // TODO Auto-generated method stub } @Override public void surfaceCreated(SurfaceHolder holder) { // TODO Auto-generated method stub myThread.isRun = true; myThread.start(); } @Override public void surfaceDestroyed(SurfaceHolder holder) { // TODO Auto-generated method stub myThread.isRun = false; } } //线程内部类 class MyThread extends Thread { private SurfaceHolder holder; public boolean isRun ; public MyThread(SurfaceHolder holder) { this.holder =holder; isRun = true; } @Override public void run() { int count = 0; while(isRun) { Canvas c = null; try { synchronized (holder) { c = holder.lockCanvas();//锁定画布,一般在锁定后就可以通过其返回的画布对象Canvas,在其上面画图等操作了。 c.drawColor(Color.BLACK);//设置画布背景颜色 Paint p = new Paint(); //创建画笔 p.setColor(Color.WHITE); Rect r = new Rect(100, 50, 300, 250); c.drawRect(r, p); c.drawText("这是第"+(count++)+"秒", 100, 310, p); Thread.sleep(1000);//睡眠时间为1秒 } } catch (Exception e) { // TODO: handle exception e.printStackTrace(); } finally { if(c!= null) { holder.unlockCanvasAndPost(c);//结束锁定画图,并提交改变。 } } } } } }