private void OnTouchMoved(Point currentPosition)
{
var elapsedTime = DateTime.Now - InitialTime;
if (elapsedTime <= InitialDelayTime)
{
return;
}
//var deltaFromInitialPosition = currentPosition - InitialPosition;
//if (deltaFromInitialPosition.Length < InitialScrollingTriggerThreshold)
//{
// return;
//}
var delta = currentPosition - PreviousPosition;
var magnitude = delta.Length * ScrollResolution;
if (ScrollOrientation == Orientation.Vertical)
{
if (currentPosition.Y < PreviousPosition.Y)
{
magnitude *= -1;
}
}
else
{
if (currentPosition.X < PreviousPosition.X)
{
magnitude *= -1;
}
}
var newOffset = (ScrollOrientation == Orientation.Vertical ?
AssociatedScrollViewer.VerticalOffset :
AssociatedScrollViewer.HorizontalOffset) + magnitude;
if (ScrollOrientation == Orientation.Vertical)
{
AssociatedScrollViewer.ScrollToVerticalOffset(newOffset);
}
else
{
AssociatedScrollViewer.ScrollToHorizontalOffset(newOffset);
}
PreviousPosition = currentPosition;
}
private void CompositionTarget_Rendering(object sender, EventArgs e)
{
lock (inertiaSync)
{
if (CurrentForce <= 0)
{
return;
}
var currentTime = DateTime.Now;
var elapsedTime = currentTime - LastUpdate;
CurrentVelocity = CurrentForce / BodyMass;
var dueDisplacement = CurrentVelocity * (Double)elapsedTime.TotalMilliseconds;
if (CurrentForceDirection == ForceDirection.Down)
{
dueDisplacement *= -1;
}
var newOffset = (ScrollOrientation == Orientation.Vertical ?
AssociatedScrollViewer.VerticalOffset :
AssociatedScrollViewer.HorizontalOffset) + dueDisplacement;
if (Double.IsNaN(newOffset))
{
return;
}
if (ScrollOrientation == Orientation.Vertical)
{
AssociatedScrollViewer.ScrollToVerticalOffset(newOffset);
}
else
{
AssociatedScrollViewer.ScrollToHorizontalOffset(newOffset);
}
CurrentForce = Math.Max(0, CurrentForce - ((Double)elapsedTime.TotalMilliseconds * CurrentForce * Friction));
if (CurrentForce < 0.0001)
{
CurrentForce = 0;
}
LastUpdate = DateTime.Now;
}
}
