Android自定义View实现转盘旋转的效果

 onDraw函数在界面刷新时会被调用，通过线程控制可以实现动画的效果，这里提供一个用自定义View实现的类似幸运转盘的例子。
一、自定义的转盘View
01 package com.demo;
02 import android.content.Context;
03 import android.content.res.Resources;
04 import android.graphics.Bitmap;
05 import android.graphics.BitmapFactory;
06 import android.graphics.Canvas;
07 import android.graphics.Matrix;
08 import android.util.AttributeSet;
09 import android.view.View;
10 //自定义的转盘View
11 public class zhuanpanView extends View implements Runnable{
12 //界面需要的图片
13 private Bitmap panpic;
14 private Bitmap panhandpic;
15 //旋转矩阵
16 private Matrix panRotate=new Matrix();
17 //平移矩阵
18 private Matrix panhandTrans=new Matrix();
19 private int x=0;
20 private boolean ifRotate=false;
21 public zhuanpanView(Context context, AttributeSet attrs) {
22 super(context, attrs);
23 Resources r=context.getResources();
24 //设置指针平移矩阵为按向量(160,160-指针的高度)平移
25 panhandTrans.setTranslate(160, 160-76);
26 //生成图片
27 panpic=BitmapFactory.decodeStream(r.openRawResource(R.drawable.pan));
28 panhandpic=BitmapFactory.decodeStream(r.openRawResource(R.drawable.panhand));
29 //用线程来刷新界面
30 Thread thread=new Thread(this);
31 thread.start();
32 }
33 //重写View类的onDraw()函数
34 @Override
35 protected void onDraw(Canvas canvas) {
36 //设置转盘旋转矩阵为以(160,160)坐标为圆心，旋转X角度
37 panRotate.setRotate(x, 160, 160);
38 canvas.drawBitmap(panpic, panRotate, null);
39 canvas.drawBitmap(panhandpic, panhandTrans, null);
40 }
41 //重写的run函数，用来控制转盘转动
42 public void run() {
43 try {
44 while(true){
45 if(ifRotate){
46 this.x+=25;
47 //这个函数强制UI线程刷新界面
48 this.postInvalidate();
49 Thread.sleep(50);
50 }
51 }
52 } catch (InterruptedException e) {
53 e.printStackTrace();
54 }
55 }
56 public void startRotate(){
57 this.ifRotate=true;
58 }
59 public void stopRotate(){
60 this.ifRotate=false;
61 }
62 } 二、主Activity
01 package com.demo;
02  
03 import android.app.Activity;
04 import android.os.Bundle;
05 import android.view.View;
06 import android.view.View.OnClickListener;
07 import android.widget.Button;
08 public class Main extends Activity {
09 /** Called when the activity is first created. */
10 private void findViewAndButton(){
11 //自定义的View
12 final zhuanpanView panView=(zhuanpanView) this.findViewById(R.id.zhuanpanView);
13 //开始旋转的按钮
14 Button startButton=(Button) this.findViewById(R.id.startButton);
15 startButton.setOnClickListener(new OnClickListener(){
16 public void onClick(View v) {
17 panView.startRotate();
18 }
19 });
20 //停止旋转的按钮
21 Button stopButton=(Button) this.findViewById(R.id.stopButton);
22 stopButton.setOnClickListener(new Button.OnClickListener(){
23 public void onClick(View v) {
24 panView.stopRotate();
25 }
26 });
27 }
28 @Override
29 public void onCreate(Bundle savedInstanceState) {
30 super.onCreate(savedInstanceState);
31 setContentView(R.layout.main);
32 findViewAndButton();
33 }
34 }