ManipulationDelta on pivot item only fires once

问题

I am trying to animate an image based on the select pivoted items position.

I am currently using the ManipulationDelta event to try and see which direction the user is swiping so that I can fade out or fade in an animated image based on the position of the pivot item.

My problem is with the ManipulationDelta event, this event is only ever called once on a pivot item, regardless of how much manipulation of the pivot control is occurring.

Does anyone know a way to make it so the pivot items ManpulationDelta event is constantly called when it is being manipulated?

回答1:

Probably your Pivot is intercepting further events. You may try to do such a thing - disable Pivot (then your Manipulations should work) and change PivotItems manually for example using TouchPanel and Touch.FrameReported. Sample code:

public MainPage()
{
   InitializeComponent();
   myPivot.IsHitTestVisible = false; // disable your Pivot
   Touch.FrameReported += Touch_FrameReported;
   TouchPanel.EnabledGestures = GestureType.HorizontalDrag; 
}

TouchPoint first;
private const int detectRightGesture = 20;

private void Touch_FrameReported(object sender, TouchFrameEventArgs e)
{
    TouchPoint mainTouch = e.GetPrimaryTouchPoint(this);
    if (mainTouch.Action == TouchAction.Down)
        first = mainTouch;
    else if (mainTouch.Action == TouchAction.Up && TouchPanel.IsGestureAvailable)
    {
        if (mainTouch.Position.X - first.Position.X < -detectRightGesture)
        {
            if (myPivot.SelectedIndex < myPivot.Items.Count - 1) myPivot.SelectedIndex++;
            else myPivot.SelectedIndex = 0;
        }
        else if (mainTouch.Position.X - first.Position.X > detectRightGesture)           
        {
            if (myPivot.SelectedIndex > 0) myPivot.SelectedIndex--;
            else myPivot.SelectedIndex = myPivot.Items.Count - 1;
        }
    }
}

来源：https://stackoverflow.com/questions/24188996/manipulationdelta-on-pivot-item-only-fires-once