Android自定义View实现弹性小球效果

public class BezierView extends View {

 Paint paint;//画笔
 Path path;//路径

 int radius = 50;//圆的半径
 int time = 100;//计数时长

 int index;
 int offsetIndex;
 float viewX, viewY;//图形中心点坐标

 float width;//屏幕宽度
 float partWidth;//屏幕宽度的1/4
 int paddingLeft, paddingRight;//图形内边距
 float x1, y1, x2, y2, x3, y3, x4, y4;//圆形左上右下四个点

 float x12, y12, x23, y23, x34, y34, x41, y41;//圆形左上右下四个点之间的渐变点

 public BezierView(Context context) {
  this(context, null);
 }

 public BezierView(Context context, AttributeSet attrs) {
  this(context, attrs, 0);
 }

 public BezierView(Context context, AttributeSet attrs, int defStyleAttr) {
  super(context, attrs, defStyleAttr);

  paint = new Paint();
  paint.setColor(ResourcesCompat.getColor(getResources(), R.color.colorPrimary, null));
  paint.setAntiAlias(true);
 }


 @Override
 protected void onDraw(Canvas canvas) {
  paddingLeft = getPaddingLeft();
  paddingRight = getPaddingRight();
  width = getWidth() - paddingLeft - paddingRight;
  partWidth = width / 4;

  path = new Path();
  path.moveTo(x1, y1);
  path.cubicTo(x1, y1, x12, y12, x2, y2);
  path.cubicTo(x2, y2, x23, y23, x3, y3);
  path.cubicTo(x3, y3, x34, y34, x4, y4);
  path.cubicTo(x4, y4, x41, y41, x1, y1);
  canvas.drawPath(path, paint);

  move();
 }


 public void move() {
  new Timer().schedule(new TimerTask() {
   @Override
   public void run() {
    if (index < time - 1) {
     index++;
     viewX = width / time * index + paddingLeft;
     viewY = 400;

     x1 = viewX - radius;
     x2 = viewX;
     x3 = viewX + radius;
     x4 = viewX;

     y1 = viewY;
     y2 = viewY - radius;
     y3 = viewY;
     y4 = viewY + radius;

     offsetIndex = index % (time / 4) + 1;

     //根据图形移动到的区域进行曲线变化
     float position = (viewX - paddingLeft) / partWidth;

     //右边半圆
     if (position >= 0 && position < 1) {
      x3 = viewX + radius + radius / (time / 4) * offsetIndex;
     } else if (position >= 1 && position < 2) {
      x3 = viewX + radius + radius;
     } else if (position >= 2 && position < 3) {
      x3 = viewX + radius + radius - radius / (time / 4) * offsetIndex;
     } else {
      x3 = viewX + radius;
     }
     x23 = x34 = x3;
     y12 = y23 = y2;

     //左边半圆
     if (position >= 1 && position < 2) {
      x1 = viewX - radius - radius / (time / 4) * offsetIndex;
     } else if (position >= 2 && position < 3) {
      x1 = viewX - radius - radius;
     } else if (position >= 3) {
      x1 = viewX - radius - radius + radius / (time / 4) * offsetIndex;
     } else {
      x1 = viewX - radius;
     }
     x12 = x41 = x1;
     y34 = y41 = y4;

     postInvalidate();
    } else {
     cancel();
    }
   }
  }, 0, 5000);
 }

}