ManipulationDeltaEventArgs.ReportBoundaryFeedback(ManipulationDelta) Method

public:
 void ReportBoundaryFeedback(System::Windows::Input::ManipulationDelta ^ unusedManipulation);

public void ReportBoundaryFeedback(System.Windows.Input.ManipulationDelta unusedManipulation);

member this.ReportBoundaryFeedback : System.Windows.Input.ManipulationDelta -> unit

Public Sub ReportBoundaryFeedback (unusedManipulation As ManipulationDelta)

Parameters

Exceptions

Examples

The following example shows an event handler for the ManipulationDelta event that calls the ReportBoundaryFeedback method when the user moves the element over the edge of its container. To test this example, follow the steps in Walkthrough: Creating Your First Touch Application and replace the code in step 5 with this code.

void Window_ManipulationDelta(object sender, ManipulationDeltaEventArgs e)
{

 Rectangle rectToMove = e.OriginalSource as Rectangle;
 Vector overshoot;

 // When the element crosses the boundary of the window, check whether 
 // the manipulation is in inertia. If it is, complete the manipulation.
 // Otherwise, report the boundary feedback.
 if (CalculateOvershoot(rectToMove, e.ManipulationContainer, out overshoot))
 {
 if (e.IsInertial)
 {
 e.Complete();
 e.Handled = true;
 return;
 }
 else
 {
 //Report that the element hit the boundary
 e.ReportBoundaryFeedback(new ManipulationDelta(overshoot, 0, new Vector(), new Vector()));
 }
 }
 
 // Move the element as usual.

 // Get the Rectangle and its RenderTransform matrix.
 Matrix rectsMatrix = ((MatrixTransform)rectToMove.RenderTransform).Matrix;

 // Rotate the Rectangle.
 rectsMatrix.RotateAt(e.DeltaManipulation.Rotation,
 e.ManipulationOrigin.X,
 e.ManipulationOrigin.Y);

 // Resize the Rectangle. Keep it square 
 // so use only the X value of Scale.
 rectsMatrix.ScaleAt(e.DeltaManipulation.Scale.X,
 e.DeltaManipulation.Scale.X,
 e.ManipulationOrigin.X,
 e.ManipulationOrigin.Y);

 // Move the Rectangle.
 rectsMatrix.Translate(e.DeltaManipulation.Translation.X,
 e.DeltaManipulation.Translation.Y);

 // Apply the changes to the Rectangle.
 rectToMove.RenderTransform = new MatrixTransform(rectsMatrix);

 e.Handled = true;
}

private bool CalculateOvershoot(UIElement element, IInputElement container, out Vector overshoot)
{
 // Get axis aligned element bounds
 var elementBounds = element.RenderTransform.TransformBounds(
 VisualTreeHelper.GetDrawing(element).Bounds);

 //double extraX = 0.0, extraY = 0.0;
 overshoot = new Vector();

 FrameworkElement parent = container as FrameworkElement;
 if (parent == null)
 {
 return false;
 }

 // Calculate overshoot. 
 if (elementBounds.Left < 0)
 overshoot.X = elementBounds.Left;
 else if (elementBounds.Right > parent.ActualWidth)
 overshoot.X = elementBounds.Right - parent.ActualWidth;

 if (elementBounds.Top < 0)
 overshoot.Y = elementBounds.Top;
 else if (elementBounds.Bottom > parent.ActualHeight)
 overshoot.Y = elementBounds.Bottom - parent.ActualHeight;

 // Return false if Overshoot is empty; otherwsie, return true.
 return !Vector.Equals(overshoot, new Vector());
}

Private Sub Window_ManipulationDelta(ByVal sender As Object, ByVal e As ManipulationDeltaEventArgs)

 Dim rectToMove As Rectangle = TryCast(e.OriginalSource, Rectangle)
 Dim overshoot As Vector

 ' When the element crosses the boundary of the window, check whether 
 ' the manipulation is in inertia. If it is, complete the manipulation.
 ' Otherwise, report the boundary feedback.
 If CalculateOvershoot(rectToMove, e.ManipulationContainer, overshoot) Then
 If e.IsInertial Then
 e.Complete()
 e.Handled = True
 Exit Sub
 Else
 'Report that the element hit the boundary

 e.ReportBoundaryFeedback(New ManipulationDelta(overshoot, 0, New Vector(), New Vector()))
 End If
 End If

 ' Move the element as usual.

 ' Get the Rectangle and its RenderTransform matrix.
 Dim rectsMatrix As Matrix = DirectCast(rectToMove.RenderTransform, MatrixTransform).Matrix

 ' Rotate the Rectangle.
 rectsMatrix.RotateAt(e.DeltaManipulation.Rotation, e.ManipulationOrigin.X, e.ManipulationOrigin.Y)

 ' Resize the Rectangle. Keep it square 
 ' so use only the X value of Scale.
 rectsMatrix.ScaleAt(e.DeltaManipulation.Scale.X, e.DeltaManipulation.Scale.X, e.ManipulationOrigin.X, e.ManipulationOrigin.Y)

 ' Move the Rectangle.
 rectsMatrix.Translate(e.DeltaManipulation.Translation.X, e.DeltaManipulation.Translation.Y)

 ' Apply the changes to the Rectangle.
 rectToMove.RenderTransform = New MatrixTransform(rectsMatrix)

 e.Handled = True
End Sub

Private Function CalculateOvershoot(ByVal element As UIElement, ByVal container As IInputElement, ByRef overshoot As Vector) As Boolean
 ' Get axis aligned element bounds
 Dim elementBounds = element.RenderTransform.TransformBounds(VisualTreeHelper.GetDrawing(element).Bounds)

 'double extraX = 0.0, extraY = 0.0;
 overshoot = New Vector()

 Dim parent As FrameworkElement = TryCast(container, FrameworkElement)
 If parent Is Nothing Then
 Return False
 End If

 ' Calculate overshoot. 
 If elementBounds.Left < 0 Then
 overshoot.X = elementBounds.Left
 ElseIf elementBounds.Right > parent.ActualWidth Then
 overshoot.X = elementBounds.Right - parent.ActualWidth
 End If

 If elementBounds.Top < 0 Then
 overshoot.Y = elementBounds.Top
 ElseIf elementBounds.Bottom > parent.ActualHeight Then
 overshoot.Y = elementBounds.Bottom - parent.ActualHeight
 End If

 ' Return false if Overshoot is empty; otherwsie, return true.
 Return Not Vector.Equals(overshoot, New Vector())
End Function

Remarks

Use the ReportBoundaryFeedback method to indicate that an element has moved beyond a certain boundary. For example, if a user moves an element outside of the bounds of a Window, you can call this method to report that to the window. When you call ReportBoundaryFeedback, the ManipulationBoundaryFeedback event occurs. By default, the Window subscribes to the ManipulationBoundaryFeedback event to provide visual feedback to the user that a boundary has been reached. You can subscribe to ManipulationBoundaryFeedback to implement custom behavior.