public ViewScrollHelper(View view, GestureHelper gestureHelper) : base(gestureHelper)
{
this.View = view;
}
public InterceptTouchHelper(ViewGroup parent, GestureHelper gestureHelper)
{
this.Parent = parent;
this.GestureHelper = gestureHelper;
}
public ScrollHelper(Context context) : this(GestureHelper.CreateDefault(context))
{
}
/// <summary>
/// 触发触摸事件
/// </summary>
/// <param name="event">事件</param>
public void OnTouchEvent(MotionEvent @event)
{
GestureHelper.OnTouchEvent(@event);
VelocityTracker.AddMovement(@event);
switch (@event.Action)
{
case MotionEventActions.Down:
{
SetStartPosition(@event.GetX(), @event.GetY());
break;
}
case MotionEventActions.Move:
{
if (CanScroll)
{
float rangeX = @event.GetX() - startTouchX;
float rangeY = @event.GetY() - startTouchY;
int dstX = (int)(startScrollX - rangeX);
int dstY = (int)(startScrollY - rangeY);
if (dstX < GetMinHorizontallyScroll)
{
dstX = 0;
startTouchX = @event.GetX();
startScrollX = dstX;
}
else if (dstX > GetMaxHorizontallyScroll)
{
dstX = GetViewHorizontallyScrollSize();
startTouchX = @event.GetX();
startScrollX = dstX;
}
if (dstY < GetMinVerticallyScroll)
{
dstY = 0;
startTouchY = @event.GetY();
startScrollY = dstY;
}
else if (dstY > GetMaxVerticallyScroll)
{
dstY = GetViewVerticallyScrollSize();
startTouchY = @event.GetY();
startScrollY = dstY;
}
ViewScrollTo(dstX, dstY);
}
break;
}
case MotionEventActions.Up:
case MotionEventActions.Cancel:
{
VelocityTracker.ComputeCurrentVelocity(1000);
if (CanScroll)
{
float xv = VelocityTracker.XVelocity;
float yv = VelocityTracker.YVelocity;
ViewFling(xv, yv);
}
break;
}
}
}
public ScrollHelper(GestureHelper gestureHelper)
{
this.GestureHelper = gestureHelper;
this.VelocityTracker = VelocityTracker.Obtain();
}