Android实现抽奖转盘

一、SurfaceView认识及的应用的思路

SurfaceView继承自（extends）View，View是在UI线程中进行绘制；
而SurfaceView是在一个子线程中对自己进行绘制，优势：避免造成UI线程阻塞；
SurfaceView中包含一个专门用于绘制的Surface，Surface中包含一个Canvas;
获得Canvas:可以从SurfaceView中方法的getHolder()获得SurfaceHolder,从holder获得Canvas;
holder还管理着SurfaceView的生命周期：

①surfaceCreated()创建子线程，子线程的run()方法中开启SurfaceView的绘制。

②surfaceChanged()。

③surfaceDestoryed()中关闭子线程。

二、SurfaceView的一般写法

 1 package com.example.luckypan;
 2 
 3 import android.content.Context;
 4 import android.graphics.Canvas;
 5 import android.util.AttributeSet;
 6 import android.view.SurfaceHolder;
 7 import android.view.SurfaceHolder.Callback;
 8 import android.view.SurfaceView;
 9 
10 public class SurfaceViewTemplate extends SurfaceView implements Callback, Runnable {
11 
12     private SurfaceHolder mHolder;
13     private Canvas mCanvas;
14     /**
15      * 用于绘制线程
16      */
17     private Thread thread;
18     /**
19      * 线程的控制开关
20      */
21     private boolean isRunning;
22     public SurfaceViewTemplate(Context context) {
23         this(context, null);
24     }
25     public SurfaceViewTemplate(Context context, AttributeSet attrs) {
26         super(context, attrs);
27         mHolder=getHolder();
28         mHolder.addCallback(this);
29         //可获得焦点
30         setFocusable(true);
31         setFocusableInTouchMode(true);
32         //设置常量
33         setKeepScreenOn(true);
34     }
35     public void surfaceCreated(SurfaceHolder holder) {
36         isRunning=true;
37         thread=new Thread(this);
38         thread.start();
39         
40     }
41     public void surfaceChanged(SurfaceHolder holder, int format, int width,
42             int height) {
43         // TODO Auto-generated method stub
44         
45     }
46     public void surfaceDestroyed(SurfaceHolder holder) {
47         isRunning=false;
48         
49     }
50     public void run() {
51         //不断进行绘制
52         while (isRunning)
53         {
54             draw();
55         }
56     }
57     private void draw() {
58         try {
59             mCanvas=mHolder.lockCanvas();
60             if (mCanvas!=null) {
61                 //
62             }
63         }
64         catch (Exception e) {
65         
66         }
67         finally
68         {
69             if (mCanvas!=null) {
70                 mHolder.unlockCanvasAndPost(mCanvas);
71             }
72         }
73     }
74 
75 
76 }

SurfaceViewTemplate