calculateMove method

void calculateMove(
  1. Offset localPosition
)

计算移动距离

Implementation

void calculateMove(Offset localPosition) {
  /// 相对位置
  Offset offset = localPosition - Offset(widget.areaSize.width / 2, widget.areaSize.height / 2) - backgroundOffset;

  /// 更新摇杆位置 活动范围控制在Size之内
  Offset handle = Offset.fromDirection(offset.direction, min(widget.size.width / 2, offset.distance));
  setState(() {
    handleOffset = handle;
  });

  /// [-pi,pi]
  updateDirection(offset.direction);
}