Android实现转盘效果

我今天也只是刚好看到这个，看到网友实现了一个转盘的效果，但试了一下好像不太行，所以就修改了一下程序最终实现转盘的效果，我对Android 绘画这一块用得不多，一般在开发游戏的时候可能会用得较多，所以很多地方都不太清楚。

下面是转盘的效果图：

布局：

 <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"
     android:background="@drawable/back"
     >

     <com.wwj.turnplate.TurnPlateView
         android:id="@+id/turnplate"
         android:layout_width="wrap_content"
         android:layout_height="wrap_content"
         android:layout_centerInParent="true"
         />

     <Button
         android:id="@+id/btnStart"
         android:layout_width="70dp"
         android:layout_height="wrap_content"
         android:layout_alignParentBottom="true"
         android:layout_alignParentLeft="true"
         android:text="开始" />

     <Button
         android:id="@+id/btnStop"
         android:layout_width="70dp"
         android:layout_height="wrap_content"
         android:layout_alignParentBottom="true"
         android:layout_alignParentRight="true"
         android:text="结束" />

 RelativeLayout>

自定义View

/2013.10.16_TurnPlate_Demo/src/com/wwj/turnplate/TurnPlateView.java

 package com.wwj.turnplate;

 import android.content.Context;
 import android.content.res.Resources;
 import android.graphics.Bitmap;
 import android.graphics.BitmapFactory;
 import android.graphics.Canvas;
 import android.graphics.Matrix;
 import android.util.AttributeSet;
 import android.view.View;


 public class TurnPlateView extends View implements Runnable{

     // 界面需要的图片
     private Bitmap turnPlatePic;        // 转盘图片
     private Bitmap pointerPic;          // 指针图片

     // 旋转矩阵
     private Matrix panRotate = new Matrix();
     // 平移矩阵
     private Matrix pointerTranslate = new Matrix();

     private int x = 0;
     private boolean ifRoate = false;


     public TurnPlateView(Context context, AttributeSet attrs) {
         super(context, attrs);
         Resources r = context.getResources();
         // 生成图片
         turnPlatePic = BitmapFactory.decodeStream(r.openRawResource(R.drawable.turnplate));
         pointerPic = BitmapFactory.decodeStream(r.openRawResource(R.drawable.pointer));

         // 用线程刷新界面
         Thread thread = new Thread(this);
         thread.start();

     }

     @Override
     protected void onDraw(Canvas canvas) {
         super.onDraw(canvas);

         canvas.translate(75, 100);
         canvas.drawBitmap(turnPlatePic, panRotate, null);
         canvas.translate(turnPlatePic.getWidth() / 2 - pointerPic.getWidth() / 2, 20);
         canvas.rotate(x, pointerPic.getWidth() / 2,pointerPic.getHeight() - 35);
         canvas.drawBitmap(pointerPic, pointerTranslate, null);

     }

     @Override
     public void run() {
         try {
             while(true) {
                 if (ifRoate) {
                     this.x += 25;
                     //这个函数强制UI线程刷新界面
                     this.postInvalidate();
                     Thread.sleep(50);
                 }
             }
         } catch(InterruptedException e) {
             e.printStackTrace();
         }
     }

     public void startRoate() {
         this.ifRoate = true;
     }

     public void stopRotate() {
         this.ifRoate = false;
     }
 }

主Activity

 package com.wwj.turnplate;

 import android.app.Activity;
 import android.os.Bundle;
 import android.view.View;
 import android.view.View.OnClickListener;
 import android.widget.Button;

 public class MainActivity extends Activity implements OnClickListener{


     private TurnPlateView plateView;
     private Button btnStart;
     private Button btnStop;


     protected void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
         setContentView(R.layout.activity_main);

         plateView = (TurnPlateView) findViewById(R.id.turnplate);
         btnStart = (Button) findViewById(R.id.btnStart);
         btnStop = (Button) findViewById(R.id.btnStop);

         btnStart.setOnClickListener(this);
         btnStop.setOnClickListener(this);
     }



     @Override
     public void onClick(View v) {
         switch(v.getId()) {
         case R.id.btnStart:
             plateView.startRoate();

             break;
         case R.id.btnStop:
             plateView.stopRotate();
             break;
         }
     }