UIElement.CaptureMouse Method

Definition

Namespace:

System.Windows

Assembly:

PresentationCore.dll

Attempts to force capture of the mouse to this element.

public:
 virtual bool CaptureMouse();

public bool CaptureMouse ();

abstract member CaptureMouse : unit -> bool
override this.CaptureMouse : unit -> bool

Public Function CaptureMouse () As Boolean

Returns

Boolean

true if the mouse is successfully captured; otherwise, false.

Implements

CaptureMouse()

Examples

The following example implements a pair of handlers for mouse and key input combination that capture (and uncapture) the mouse and enable a special mouse mode for viewing a 3D model.

private void MouseDownHandler(object sender, MouseButtonEventArgs e)
{
    if (!Enabled) return;
    e.Handled = true;

    if (Keyboard.IsKeyDown(Key.F1) == true)
    {
        Reset();
        return;
    }

    UIElement el = (UIElement)sender;
    _point = e.MouseDevice.GetPosition(el);
    // Initialize the center of rotation to the lookatpoint
    if (!_centered)
    {
        ProjectionCamera camera = (ProjectionCamera)_slaves[0].Camera;
        _center = camera.LookDirection;
        _centered = true;
    }

    _scaling = (e.MiddleButton == MouseButtonState.Pressed);

    if (Keyboard.IsKeyDown(Key.Space) == false)
        _rotating = true;
    else
        _rotating = false;

    el.CaptureMouse();
}

private void MouseUpHandler(object sender, MouseButtonEventArgs e)
{
    if (!_enabled) return;
    e.Handled = true;

    // Stuff the current initial + delta into initial so when we next move we
    // start at the right place.
    if (_rotating == true)
    {
        _rotation = _rotationDelta * _rotation;
    }
    else
    {
        _translate += _translateDelta;
        _translateDelta.X = 0;
        _translateDelta.Y = 0;
    }

    //_scale = _scaleDelta*_scale;
    UIElement el = (UIElement)sender;
    el.ReleaseMouseCapture();
}

Private Sub MouseDownHandler(ByVal sender As Object, ByVal e As MouseButtonEventArgs)
    If Not Enabled Then
        Return
    End If
    e.Handled = True


    If Keyboard.IsKeyDown(Key.F1) = True Then
        Reset()
        Return
    End If

    Dim el As UIElement = CType(sender, UIElement)
    _point = e.MouseDevice.GetPosition(el)
    ' Initialize the center of rotation to the lookatpoint
    If Not _centered Then
        Dim camera As ProjectionCamera = CType(_slaves(0).Camera, ProjectionCamera)
        _center = camera.LookDirection
        _centered = True
    End If

    _scaling = (e.MiddleButton = MouseButtonState.Pressed)

    If Keyboard.IsKeyDown(Key.Space) = False Then
        _rotating = True
    Else
        _rotating = False
    End If

    el.CaptureMouse()
End Sub

Private Sub MouseUpHandler(ByVal sender As Object, ByVal e As MouseButtonEventArgs)
    If Not _enabled Then
        Return
    End If
    e.Handled = True

    ' Stuff the current initial + delta into initial so when we next move we
    ' start at the right place.
    If _rotating = True Then
        _rotation = _rotationDelta * _rotation
    Else
        _translate += _translateDelta
        _translateDelta.X = 0
        _translateDelta.Y = 0
    End If

    '_scale = _scaleDelta * _scale
    Dim el As UIElement = CType(sender, UIElement)
    el.ReleaseMouseCapture()
End Sub

Remarks

To be captured, an element must be enabled. Check whether IsEnabled is true before you call CaptureMouse.

If calling CaptureMouse returns true, then IsMouseCaptured is also true.

If calling CaptureMouse returns true, then the GotMouseCapture and IsMouseCapturedChanged events are raised, with RoutedEventArgs.Source in the event data reported as the element where the CaptureMouse method is called. If you force capture, you might interfere with existing captures - especially with captures that relate to drag-and-drop with the mouse.

To clear mouse capture from all elements, call Mouse.Capture with the element parameter provided as null.

See also

• IsMouseCaptured