Android 旋转动画实现抽奖转盘

项目要求做一个类似转盘抽奖的东西出来，还要求转的过程中要变速，变就变吧，要求阶段函数样式的变速。。。。
想了好多种办法，写好几段旋转动画拼凑成一圈，然后放到 AnimatorSet中，循环播放这个AnimatorSet，但是找了半天也没找到循环方式，于是在回调中重新开启了一下动画集

ObjectAnimator objectAnimator1 = ObjectAnimator.ofFloat(image, "rotation", 0f, 90f).setDuration(500);
ObjectAnimator objectAnimator2 = ObjectAnimator.ofFloat(image, "rotation", 90f,180f).setDuration(2000);
ObjectAnimator objectAnimator3 = ObjectAnimator.ofFloat(image, "rotation", 180f,270f).setDuration(3000);
ObjectAnimator objectAnimator4 = ObjectAnimator.ofFloat(image, "rotation", 270f,360f).setDuration(500);
final AnimatorSet animatorSet = new AnimatorSet();
animatorSet.playSequentially(objectAnimator1,objectAnimator2,objectAnimator3,objectAnimator4);
animatorSet.setInterpolator(new LinearInterpolator());
//周期间不停顿
animatorSet.start();
animatorSet.addListener(new Animator.AnimatorListener() {
    @Override    
    public void onAnimationStart(Animator animation) {}
    @Override    
    public void onAnimationEnd(Animator animation) {
      animatorSet.start();    
    }
    @Override    
    public void onAnimationCancel(Animator animation) {}
    @Override    
    public void onAnimationRepeat(Animator animation) {}
});

可是这样就不能随时停止动画了。。。。

那么就只写一个动画，控制速度就好了，但事实是Interpolator回调方法里的参数并不是旋转的速度，而是一个与时间有关的参数，而返回值是旋转的位置。。。。

那么问题来了，我需要根据参数，自己计算出需要的返回值，经过操作，行不通，好吧，无爱了

不想说话了，直接上代码吧

Demo.java

import android.animation.ObjectAnimator;
import android.animation.TimeInterpolator;
import android.animation.ValueAnimator;
import android.app.Activity;
import android.os.Bundle;
import android.util.Log;
import android.view.MotionEvent;
import android.view.View;
import android.widget.Button;
import android.widget.ImageView;
import android.widget.Toast;
/**
 * Created by jiangtao on 2016/8/16.
 */
public class Demo extends Activity {
    private ImageView image;    
    private float currentPoint;    
    private Button btn;    
    private ObjectAnimator objectAnimator = null;    
    @Override    
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);        
        setContentView(R.layout.activity_demo);        
        btn = (Button) findViewById(R.id.btn);        
        btn.setOnTouchListener(new View.OnTouchListener() {
              @Override            
              public boolean onTouch(View v, MotionEvent event) {
                  switch (event.getAction()) {
                      case MotionEvent.ACTION_DOWN:
                          objectAnimator.start();                        
                      break;                   
                      case MotionEvent.ACTION_UP:
                          Log.e("TAG", "" + objectAnimator.getAnimatedFraction() + "," + objectAnimator.getCurrentPlayTime() + "," + objectAnimator.getDuration());
                          //                        objectAnimator.pause();                        
                          Log.e("TAG", "" + objectAnimator.getAnimatedFraction() % 1.0f);
                          currentPoint = objectAnimator.getAnimatedFraction() % 1.0f;
                          objectAnimator.cancel();
                          if (currentPoint == 0.25 || currentPoint == 0.5 || currentPoint == 0.75 || currentPoint == 0) {Log.e("TAG","金奖"); 
                              Toast.makeText(Demo.this, "卧槽，真的假的？！！", Toast.LENGTH_SHORT).show();
                          }else if (currentPoint > 0.245 && currentPoint < 0.255
                                || currentPoint > 0.495 && currentPoint < 0.505
                                || currentPoint > 0.745 && currentPoint < 0.755) {
                              Log.e("TAG","银奖");
                              Toast.makeText(Demo.this, "你中了~", Toast.LENGTH_SHORT).show();
                          }else {
                              Toast.makeText(Demo.this, "是你手残，不要怪我~", Toast.LENGTH_SHORT).show();
                          }break;
                  }
                  return false; 
            }
        });
        image = (ImageView) findViewById(R.id.img_view);
        /** 设置旋转动画 */
        objectAnimator = ObjectAnimator.ofFloat(image, "rotation", 0f, 359f).setDuration(500);
        /** 常用方法 */
        objectAnimator.setRepeatCount(-1);
        //设置重复次数
        objectAnimator.setInterpolator(new MyInterpolator());//周期间不停顿
        objectAnimator.setRepeatMode(ValueAnimator.INFINITE);//动画重复模式
        //        animation.setFillAfter(true);
        //动画执行完后是否停留在执行完的状态
        //animation.setStartOffset(long startOffset);
        //执行前的等待时间
    }
  public class MyInterpolator implements TimeInterpolator {
      @Override
      public float getInterpolation(float input) {
      //            Log.e("TAG", "getInterpolation: " + input);
              float mTension = 2.0f; 
//              return input * input * ((mTension + 1) * input + mTension) + 1.0f;
//              return (float)(Math.sin(2 * 1 * Math.PI * input));
              return (float) (Math.cos((input + 1) * Math.PI) / 2.0f) + 0.5f;
//              return input;
      }
  }
}

activity_demo.xml

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent">
    <ImageView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_centerHorizontal="true"
        android:layout_centerVertical="true"
        android:src="@drawable/disk" />
    <ImageView
        android:id="@+id/img_view"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_centerHorizontal="true"
        android:layout_centerVertical="true"
        android:src="@drawable/start" />
    <Button
        android:id="@+id/btn"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentBottom="true"
        android:layout_centerHorizontal="true"
        android:layout_gravity="bottom" />
</RelativeLayout>

是不是感觉很乱？那就对了，不乱我贴给你看？用个屏幕大点的，横屏看吧。。。反正基本抽奖功能实现了。。。。

贴代码还是很还看的：）