Android自定義View實現彈性小球效果

照例先看效果圖

自定義代碼示例

public class BezierView extends View {

 Paint paint;//畫筆
 Path path;//路徑

 int radius = 50;//圓的半徑
 int time = 100;//計數時長

 int index;
 int offsetIndex;
 float viewX, viewY;//圖形中心點坐標

 float width;//屏幕寬度
 float partWidth;//屏幕寬度的1/4
 int paddingLeft, paddingRight;//圖形內邊距
 float x1, y1, x2, y2, x3, y3, x4, y4;//圓形左上右下四個點

 float x12, y12, x23, y23, x34, y34, x41, y41;//圓形左上右下四個點之間的漸變點

 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;

     //根據圖形移動到的區域進行曲線變化
     float position = (viewX - paddingLeft) / partWidth;

     //右邊半圓
     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;

     //左邊半圓
     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);
 }

}

總結

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