TouchDevice Class
Represents a single touch input produced by a finger on a touchscreen.
System.Windows.Threading.DispatcherObject
System.Windows.Input.InputDevice
System.Windows.Input.TouchDevice
Assembly: PresentationCore (in PresentationCore.dll)
The TouchDevice type exposes the following members.
| Name | Description | |
|---|---|---|
![]() | TouchDevice | Called from constructors in derived classes to initialize the TouchDevice class. |
| Name | Description | |
|---|---|---|
![]() | ActiveSource | Gets the PresentationSource that is reporting input for this device. (Overrides InputDevice.ActiveSource.) |
![]() | Captured | Gets the element that captured the TouchDevice. |
![]() | CaptureMode | Gets the capture policy of the TouchDevice. |
![]() | DirectlyOver | Gets the element that the touch contact point is directly over. |
![]() | Dispatcher | Gets the Dispatcher this DispatcherObject is associated with. (Inherited from DispatcherObject.) |
![]() | Id | Gets the unique identifier of the TouchDevice, as provided by the operating system. |
![]() | IsActive | Gets a value that indicates whether the device is active. |
![]() | Target | Gets the element that receives input from the TouchDevice. (Overrides InputDevice.Target.) |
| Name | Description | |
|---|---|---|
![]() | Activate | Adds the TouchDevice to the input messaging system. |
![]() | Capture(IInputElement) | Captures a touch to the specified element by using the Element capture mode. |
![]() | Capture(IInputElement, CaptureMode) | Captures a touch to the specified element by using the specified CaptureMode. |
![]() | CheckAccess | Determines whether the calling thread has access to this DispatcherObject. (Inherited from DispatcherObject.) |
![]() | Deactivate | Removes the TouchDevice from the input messaging system. |
![]() | Equals(Object) | Determines whether the specified Object is equal to the current Object. (Inherited from Object.) |
![]() | Finalize | Allows an object to try to free resources and perform other cleanup operations before it is reclaimed by garbage collection. (Inherited from Object.) |
![]() | GetHashCode | Serves as a hash function for a particular type. (Inherited from Object.) |
![]() | GetIntermediateTouchPoints | When overridden in a derived class, returns all touch points that are collected between the most recent and previous touch events. |
![]() | GetTouchPoint | Returns the current position of the touch device relative to the specified element. |
![]() | GetType | Gets the Type of the current instance. (Inherited from Object.) |
![]() | MemberwiseClone | Creates a shallow copy of the current Object. (Inherited from Object.) |
![]() | OnCapture | Called when a touch is captured to an element. |
![]() | OnManipulationEnded | Called when a manipulation has ended. |
![]() | OnManipulationStarted | Called when a manipulation is started. |
![]() | ReportDown | Reports that a touch is pressed on an element. |
![]() | ReportMove | Reports that a touch is moving across an element. |
![]() | ReportUp | Reports that a touch was lifted from an element. |
![]() | SetActiveSource | Sets the PresentationSource that is reporting input for this device. |
![]() | Synchronize | Forces the TouchDevice to synchronize the user interface with underlying touch points. |
![]() | ToString | Returns a string that represents the current object. (Inherited from Object.) |
![]() | VerifyAccess | Enforces that the calling thread has access to this DispatcherObject. (Inherited from DispatcherObject.) |
| Name | Description | |
|---|---|---|
![]() | Activated | Occurs when the TouchDevice is added to the input messaging system. |
![]() | Deactivated | Occurs when the TouchDevice is removed from the input messaging system. |
![]() | Updated | Occurs when a touch message is sent. |
| Name | Description | |
|---|---|---|
![]() ![]() | IManipulator.GetPosition | Returns the position of the IManipulator object. |
![]() ![]() | IManipulator.Id | Gets the unique identifier of the TouchDevice as provided by the operating system. |
![]() ![]() | IManipulator.ManipulationEnded | Occurs when a manipulation has ended. |
You typically access a TouchDevice by using the TouchEventArgs.TouchDevice property. A TouchDevice represents a single touch on a screen. If multiple touches are present, use the Id property to distinguish between them.
Note |
|---|
This class contains an inheritance demand at the class level that applies to all members. A SecurityException is thrown when the derived class does not have full-trust permission. For more information about security demands, see Link Demands and Inheritance Demands. |
The following example enables you to create simple patterns on a Canvas by dragging two fingers on a touchscreen. Each touch is represented by a TouchDevice in the TouchEventArgs. The pattern is created by drawing a line between the touch points that are provided by the touches. This example requires a Windows Touch–compatible screen.
The following markup creates the user interface, which consists of a Canvas that is centered in a grid, and attaches the event handlers for the touch events.
<Window x:Class="WpfTouchEventsSample.MainWindow" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" Title="MainWindow" Height="525" Width="525"> <Grid> <Canvas x:Name="canvas1" Width="500" Height="500" Background="Black" TouchDown="canvas_TouchDown" TouchMove="canvas_TouchMove" TouchUp="canvas_TouchUp" /> </Grid> </Window>
The following code handles the touch events. When a touch is pressed on the Canvas, the TouchDevice is captured to the Canvas. When the touch is lifted, the TouchDevice is released. When a touch moves on the Canvas, the Id is checked. If the move came from the first touch, its location is recorded. If the move came from the second touch, a line is drawn from the position of the first touch to the position of the second touch.
Class MainWindow ' Variables to track the first two touch points ' and the ID of the first touch point. Private pt1, pt2 As Point Private firstTouchId As Integer = -1 ' Touch Down Private Sub canvas_TouchDown(ByVal sender As System.Object, ByVal e As System.Windows.Input.TouchEventArgs) Dim _canvas As Canvas = CType(sender, Canvas) If (_canvas IsNot Nothing) Then _canvas.Children.Clear() e.TouchDevice.Capture(_canvas) ' Record the ID of the first touch point if it hasn't been recorded. If firstTouchId = -1 Then firstTouchId = e.TouchDevice.Id End If End If End Sub ' Touch Move Private Sub canvas_TouchMove(ByVal sender As System.Object, ByVal e As System.Windows.Input.TouchEventArgs) Dim _canvas As Canvas = CType(sender, Canvas) If (_canvas IsNot Nothing) Then Dim tp = e.GetTouchPoint(_canvas) ' This is the first touch point; just record its position. If e.TouchDevice.Id = firstTouchId Then pt1.X = tp.Position.X pt1.Y = tp.Position.Y ' This is not the first touch point; draw a line from the first point to this one. ElseIf e.TouchDevice.Id <> firstTouchId Then pt2.X = tp.Position.X pt2.Y = tp.Position.Y Dim _line As New Line() _line.Stroke = New RadialGradientBrush(Colors.White, Colors.Black) _line.X1 = pt1.X _line.X2 = pt2.X _line.Y1 = pt1.Y _line.Y2 = pt2.Y _line.StrokeThickness = 2 _canvas.Children.Add(_line) End If End If End Sub ' Touch Up Private Sub canvas_TouchUp(ByVal sender As System.Object, ByVal e As System.Windows.Input.TouchEventArgs) Dim _canvas As Canvas = CType(sender, Canvas) If (_canvas IsNot Nothing AndAlso e.TouchDevice.Captured Is _canvas) Then _canvas.ReleaseTouchCapture(e.TouchDevice) End If End Sub End Class
- UIPermission
for deriving from this class. Security action: InheritanceDemand. Associated enumeration: PermissionState.Unrestricted
Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2
The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.







Note