Android自定义View实现饼状图带动画效果

public class Yidong2 extends AppCompatActivity {
 @Override
 protected void onCreate(Bundle savedInstanceState) {
  super.onCreate(savedInstanceState);
  setContentView(new PointView(this));
 }
 
 public class PointView extends View {
  private int[] p1 = {0, 100, 200};  //存放弧度的数组
  //定义存放颜色的数组
  private int[] p2 = {Color.GREEN, Color.YELLOW, Color.RED};  
  Paint paint = new Paint();    //画笔
  private float k;      //弧度变动后的值
 
  //定义矩形，用户确定描绘的饼状图位置
  private final RectF rectF = new RectF(100, 100, 800, 800);
 
  //定义
  public PointView(Context context) {
   super(context);
   paint.setStyle(Paint.Style.FILL);  //设置画笔为填充
   paint.setStrokeWidth(10f);    //设置画笔宽度
   paint.setAntiAlias(true);    //抗锯齿
 
   //属性动画
   ValueAnimator animator = ValueAnimator.ofFloat(0, 360);
   animator.setDuration(1000);    //设置动画时间
   animator.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {
    @Override
    public void onAnimationUpdate(ValueAnimator animation) {
     k = (float) animation.getAnimatedValue(); //获取变动后的值
     invalidate();   //刷新布局
    }
   });
   animator.start(); //启动动画
  }
 
  @SuppressLint("DrawAllocation")
  @RequiresApi(api = Build.VERSION_CODES.LOLLIPOP)
  @Override
  protected void onDraw(Canvas canvas) {
   super.onDraw(canvas);
   //这里做了不同颜色的范围判断，还可以进行封装，为了便于学习，就没有再次封装
   if (k