public class MySearch extends View {
  Paint paint;
  Path searchPath; //搜索的圓
  Path ciclePath; //外圓
  //獲得寬高
  int w;
  int h;
  //這是保存截取時(shí)，返回的坐標(biāo)點(diǎn)
  float serpos[];
  float cicpos[];
  //測(cè)量 path 的類
  PathMeasure measure;
  //動(dòng)畫(huà)產(chǎn)生的實(shí)時(shí)數(shù)據(jù)
  float value;
  public MySearch(Context context) {
    this(context,null);
  }
  public MySearch(Context context, @Nullable AttributeSet attrs) {
    this(context,attrs,0);
  }
  public MySearch(Context context, @Nullable AttributeSet attrs, int defStyleAttr) {
    super(context, attrs, defStyleAttr);
    //獲得屏幕的寬高
    WindowManager wm = (WindowManager) context.getSystemService(Context.WINDOW_SERVICE);
    w = wm.getDefaultDisplay().getWidth();
    h = wm.getDefaultDisplay().getHeight();
    //初始化數(shù)據(jù)
    serpos = new float[2];
    cicpos = new float[2];
    //畫(huà)筆
    paint = new Paint();
    paint.setStyle(Paint.Style.STROKE);
    paint.setDither(true);
    paint.setStrokeWidth(6);
    paint.setAntiAlias(true);
    //初始化路徑
    initPath();
    //初始化動(dòng)畫(huà)
    initAnimator();
  }
  @Override
  protected void onDraw(Canvas canvas) {
    super.onDraw(canvas);
    //移動(dòng)畫(huà)布的遠(yuǎn)點(diǎn)到屏幕中心
    canvas.translate(w/2,h/5);
    paint.setColor(Color.BLUE);
    //這是截取方法返回的路徑
    Path dra = new Path();
    //解除硬件加速，不然沒(méi)效果
    dra.reset();
    dra.lineTo(0,0);
    //設(shè)置當(dāng)前需要測(cè)量的path
    measure.setPath(searchPath,false);
    //開(kāi)始截取
    boolean s = measure.getSegment(measure.getLength()*value,measure.getLength(),dra,true);
    //繪制路徑
    canvas.drawPath(dra,paint);
  }
  /**
   * 初始化路徑
   */
  public void initPath(){
    paint.setColor(Color.BLUE);
    //搜索的圓
    searchPath = new Path();
    RectF rectF = new RectF(-50,-50,50,50);
    searchPath.addArc(rectF,45,359.9f);
    //輔助圓
    ciclePath = new Path();
    RectF rectF1 = new RectF(-100,-100,100,100);
    ciclePath.addArc(rectF1,45,359.9f);
    //測(cè)量類
    measure = new PathMeasure();
    measure.setPath(searchPath,false);
    //獲取坐標(biāo)
    measure.getPosTan(0,serpos,null);
    measure.setPath(ciclePath,false);
    //獲取坐標(biāo)
    measure.getPosTan(0,cicpos,null);
    //根據(jù)兩點(diǎn)坐標(biāo)繪制線
    searchPath.lineTo(cicpos[0],cicpos[1]);
  }
  /**
   * 初始化動(dòng)畫(huà)
   */
  public void initAnimator(){
    ValueAnimator animator = ValueAnimator.ofFloat(0,1);
    animator.setDuration(2600);
    animator.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {
      @Override
      public void onAnimationUpdate(ValueAnimator animation) {
        value = (float) animation.getAnimatedValue();
        postInvalidate();
      }
    });
    animator.start();
  }
}