onPointerMove method

Implementation

@override
bool? onPointerMove(PointerMoveEvent e) {
  assert(velocityTracker != null);
  // 添加触摸的数据，当触摸结束后会计算最终的速度
  velocityTracker!.addPosition(e.timeStamp, e.position);

  bool isActive = true;

  // 指针首次移动会触发 onDragStart 事件，后续移动才触发 onDragUpdate 事件
  if (isActiveDrag != true) {
    final moveDelta = e.position - pointerDownEvent!.position;

    // 移动范围需要到达一定幅度才触发拖拽
    if (moveDelta.distance <= activeDelta) return false;

    isActiveDrag = true;
    // 确定拖拽方向
    final direction = moveDelta.direction;
    final angle = horizontalAngle;
    if ((-angle <= direction && direction <= angle) ||
        (direction <= -pi + angle || direction >= pi - angle)) {
      _dragDireaction = e.delta.dx < 0
          ? AxisDirection.left
          : AxisDirection.right;
    } else {
      _dragDireaction = e.delta.dy < 0
          ? AxisDirection.up
          : AxisDirection.down;
    }

    if (triggerDrag) {
      final result = onDragStart(
        ElDragStartDetails(
          pointerDownEvent: pointerDownEvent!,
          dragDirection: dragDireaction,
        ),
      );

      // 若 onDragStart 返回 true，则关闭竞技场并忽略其他指针，反之将自身排除
      if (result == true) {
        ElPointerManager.isOpen = false;
        ElPointerManager.eager(hashCode);
      } else {
        ElPointerManager.removePointer(hashCode);
        isActive = false;
      }
    } else {
      ElPointerManager.removePointer(hashCode);
      isActive = false;
    }
  }

  if (isActive) {
    onDragUpdate(
      DragUpdateDetails(
        sourceTimeStamp: e.timeStamp,
        globalPosition: e.position,
        localPosition: e.localPosition,
        delta: calcDelta(e.delta),
        primaryDelta: calcPrimaryDelta(e.delta),
      ),
    );
  } else {
    isActiveDrag = null;
    velocityTracker = null;
  }

  return null;
}