WP8 Toolkit GestureListener Pinch Gesture - In or Out?

Question

I have this in my XAML:

<toolkit:GestureService.GestureListener>
    <toolkit:GestureListener PinchCompleted="GestureListener_PinchCompleted"/>
</toolkit:GestureService.GestureListener>

As you can see, it creates an event handler for when a pinch is completed. I have this in my code:

private void GestureListener_PinchCompleted(object sender, PinchGestureEventArgs e)
{
    //how do I determine whether it was a pinch in or pinch out gesture?
}

When this event fires, I want to know whether the gesture was pinch in or pinch out (ie, whether we are zooming out or zooming in, respectively).

This is everything I can access:

e.DistanceRatio
e.Handled
e.OriginalSource
e.TotalAngleDelta

I just need to know whether the user wants to "zoom" in or out - I can handle the animations and everything else.

Answer 1

PinchStarted="OnPinchStarted"  add event in XAML


private void OnPinchStarted(object sender, PinchStartedGestureEventArgs e)
{

}

Detect first coordinates of Pinch start and in

private void GestureListener_PinchCompleted(object sender, PinchGestureEventArgs e)
{

}

Try to determine. I think the answer will be if you cannot access the coordinates, then in e.DistanceRatio

I think that e.DistanceRatio - will return distance between fingers.

So if OnPinchStart it was 2 cm and on PinchEnd it is 1cm = Zoom In

Answer 2

The e.DistanceRatio determines the DistanceBetweenFingersAfter / DistanceBetweenFingersBefore. Thus making it

if(e.DistanceRatio > 1){
//Zoom in
} else {
// Zoom out
}

Answer 3

Forgot to post this earlier. The Distance Ratio doesn't exactly work, because it's not always correct. I did this instead:

private void GestureListener_PinchStarted(object sender, PinchStartedGestureEventArgs e)
{
    initialDistance = e.Distance;
}

private void GestureListener_PinchCompleted(object sender, PinchGestureEventArgs e)
{
    double distance2 = e.DistanceRatio * initialDistance;

    if (initialDistance > distance2)
    {
        //zoom out
    }
    else if (initialDistance < distance2)
    {
        //zoom in
    }
}