/// <summary>
/// Averages the position of the touchEvent.HitTestDetails position based on the number of touches.
/// </summary>
/// <param name="touchEvent">The new TouchTargetEvent</param>
/// <param name="hitTestDetails">The contacEvent.HitTestDetails as ScrollViewerHitTestDetails</param>
/// <param name="averageX"></param>
/// <param name="averageY"></param>
private void AverageTouchPosition(TouchTargetEvent touchEvent,
ScrollViewerHitTestDetails hitTestDetails,
out float averageX, out float averageY)
{
// Get the down hitTestDetails for this touch.
ScrollViewerHitTestDetails downDetails =
touchDownTouchInformation[touchEvent.Touch.Id].HitTestDetails as ScrollViewerHitTestDetails;
// Calculate how much has changed since last move.
averageX = (downDetails.HorizontalPosition - hitTestDetails.HorizontalPosition) * HorizontalViewportSize;
averageY = (downDetails.VerticalPosition - hitTestDetails.VerticalPosition) * VerticalViewportSize;
// Average the change by the number of touches on the Surface.
averageX /= touchDownTouchInformation.Count;
averageY /= touchDownTouchInformation.Count;
}
/// <summary>
/// Updates manipulators to reflect the touch change.
/// </summary>
/// <param name="touchEvent">The new TouchTargetEvent</param>
/// <param name="details">The contacEvent.HitTestDetails as ScrollViewerHitTestDetails</param>
private void UpdateCurrentManipulators(TouchTargetEvent touchEvent, ScrollViewerHitTestDetails details)
{
// Try to find the changed touch in the manipulators list.
bool foundManipulator = false;
for (int i = 0; i < manipulations.Count; i++)
{
Manipulator2D manipulator = manipulations[i];
if (manipulator.Id == touchEvent.Touch.Id)
{
manipulations.Remove(manipulator);
Manipulator2D manipulatorToAdd = new Manipulator2D(touchEvent.Touch.Id,
ConvertFromHorizontalValueToScreenSpace(details.HorizontalPosition),
ConvertFromVerticalValueToScreenSpace(details.VerticalPosition));
// Performance: It doesn't matter where we insert, but if all the touches are being updated,
// then putting the most recent change at the end will mean that there is one less touch
// to go through the next time this loop is executed.
if (manipulations.Count == 0)
{
manipulations.Add(manipulatorToAdd);
}
else
{
manipulations.Insert(manipulations.Count - 1, manipulatorToAdd);
}
foundManipulator = true;
break;
}
}
// The manipulator isn't in the list so add it.
if (!foundManipulator)
{
manipulations.Add(new Manipulator2D(touchEvent.Touch.Id,
ConvertFromHorizontalValueToScreenSpace(details.HorizontalPosition),
ConvertFromVerticalValueToScreenSpace(details.VerticalPosition)));
}
}
/// <summary>
/// Averages the position of the contactEvent.HitTestDetails position based on the number of contacts.
/// </summary>
/// <param name="contactEvent">The new ContactTargetEvent</param>
/// <param name="hitTestDetails">The contacEvent.HitTestDetails as ScrollViewerHitTestDetails</param>
/// <param name="averageX"></param>
/// <param name="averageY"></param>
private void AverageContactPosition(ContactTargetEvent contactEvent,
ScrollViewerHitTestDetails hitTestDetails,
out float averageX, out float averageY)
{
// Get the down hitTestDetails for this contact.
ScrollViewerHitTestDetails downDetails =
contactDownContactInformation[contactEvent.Contact.Id].HitTestDetails as ScrollViewerHitTestDetails;
// Calculate how much has changed since last move.
averageX = (downDetails.HorizontalPosition - hitTestDetails.HorizontalPosition) * HorizontalViewportSize;
averageY = (downDetails.VerticalPosition - hitTestDetails.VerticalPosition) * VerticalViewportSize;
// Average the change by the number of contacts on the Surface.
averageX /= contactDownContactInformation.Count;
averageY /= contactDownContactInformation.Count;
}
