这并非完全无关紧要,但一种方法是使用 GestureService
this.gestureListener = GestureService.GetGestureListener(containerPage);
this.gestureListener.DragStarted += gestureListener_DragStarted;
this.gestureListener.DragCompleted += gestureListener_DragCompleted;
this.gestureListener.DragDelta += gestureListener_DragDelta;
但是,它有一些错误。例如, DragCompleted 并不总是被引发,因此您需要使用 ManipulationCompleted 事件仔细检查,这似乎更可靠。
containerPage.ManipulationStarted += delegate { this.manipulationInProgress = true; };
containerPage.ManipulationCompleted += delegate
{
this.manipulationInProgress = false;
PerformDragComplete();
};
另一个问题是 DragDelta 偶尔会报告错误的坐标。所以你需要这样的修复:
Point refPosition = e.GetPosition(null);
if (refPosition.X == 0 && refPosition.Y == 0)
{
Tracer.WriteLine("Skipping buggy event");
return;
}
最后,您可以找到 list 是否一直位于顶部:
public double VerticalOffset
{
get
{
ViewportControl viewportControl = this.FindChildByName("ViewportControl") as ViewportControl;
if (viewportControl != null)
{
Tracer.WriteLine("ViewPort.Bounds.Top=" + viewportControl.Bounds.Top + " ViewPort.Top=" + viewportControl.Viewport.Top.ToString() + " State=" + this.ManipulationState);
return viewportControl.Bounds.Top - viewportControl.Viewport.Top;
}
return double.NaN;
}
}