protected override void OnAttached()
{
base.OnAttached();
// Initializes the manipulation processor.
_manipulationProcessor = new ManipulationProcessor2D(Manipulations2D.All);
_manipulationProcessor.Started += OnManipulationStarted;
_manipulationProcessor.Delta += OnManipulationDelta;
_manipulationProcessor.Completed += OnManipulationCompleted;
// Initializes the touch helper.
TouchHelper.AddHandlers(AssociatedObject, new TouchHandlers
{
TouchDown = OnTouchDown,
CapturedTouchReported = OnCapturedTouchReported
});
TouchHelper.EnableInput(true);
TouchHelper.SetRootElement(TouchHelper.GetRootElement(AssociatedObject));
_renderTransform = AssociatedObject.RenderTransform as CompositeTransform;
if (_renderTransform == null)
{
throw new InvalidCastException();
}
_initialCenter = new Point(_renderTransform.CenterX, _renderTransform.CenterY);
}
protected override void OnDetaching()
{
base.OnDetaching();
_manipulationProcessor.Started -= OnManipulationStarted;
_manipulationProcessor.Delta -= OnManipulationDelta;
_manipulationProcessor.Completed -= OnManipulationCompleted;
TouchHelper.RemoveHandlers(AssociatedObject);
}
private void OnCapturedTouchReported(object sender, TouchReportedEventArgs e)
{
var parent = AssociatedObject.Parent as UIElement;
if (parent == null)
{
return;
}
var root = TouchHelper.GetRootElement(parent);
if (root == null)
{
return;
}
List<Manipulator2D> manipulators = null;
if (e.TouchPoints.FirstOrDefault() != null)
{
// Get transformation to convert positions to the parent's coordinate system.
var transform = root.TransformToVisual(parent);
foreach (var touchPoint in e.TouchPoints)
{
var position = touchPoint.Position;
// Convert to the parent's coordinate system.
position = transform.Transform(position);
// Create a manipulator.
var manipulator = new Manipulator2D(
touchPoint.TouchDevice.Id,
(float)(position.X),
(float)(position.Y));
if (manipulators == null)
{
// Lazy initialization.
manipulators = new List<Manipulator2D>();
}
manipulators.Add(manipulator);
}
}
// Process manipulations.
_manipulationProcessor.ProcessManipulators(DateTime.UtcNow.Ticks, manipulators);
}
