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MouseEventHandler Delegate

Represents the method that will handle mouse related routed events that do not specifically involve mouse buttons or the mouse wheel; for example, UIElement.MouseMove.

Namespace:  System.Windows.Input
Assembly:  PresentationCore (in PresentationCore.dll)

public delegate void MouseEventHandler(
	Object sender,
	MouseEventArgs e
)

Parameters

sender
Type: System.Object

The object where the event handler is attached.

e
Type: System.Windows.Input.MouseEventArgs

The event data.

This delegate is used with the following attached events:

This delegate is used with the following routed events. These routed events forward the previously listed attached events to make them more accessible to the general element model in WPF.

The attached events and the base element routed events share their event data, and the bubbling and tunneling versions of the routed events also share event data. This can affect the handled characteristics of the event as it travels the event route. For details, see Input Overview.

Other than the RoutedEventArgs properties that are relevant for all routed events, the most interesting properties of MouseEventArgs that you might use in a MouseEventHandler implementation are several properties that expose the current button state, such as LeftButton and MouseDevice. MouseDevice is useful particularly because you can check Captured on it.

Note that events that specifically deal with mouse button events use a different delegate, MouseButtonEventHandler. The mouse button properties are available on MouseEventArgs in case there are input modes or interactions that involve the buttons even if you are handling a non-button event.

This example shows how to change the dimensions of an object when the mouse pointer moves on the screen.

The example includes an Extensible Application Markup Language (XAML) file that creates the user interface (UI) and a code-behind file that creates the event handler.

The following XAML creates the UI, which consists of an Ellipse inside of a StackPanel, and attaches the event handler for the MouseMove event.

<Window x:Class="WCSamples.Window1"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    Title="mouseMoveWithPointer"
    Height="400"
    Width="500"
    >
  <Canvas MouseMove="MouseMoveHandler"
          Background="LemonChiffon">
    <Ellipse Name="ellipse" Fill="LightBlue" 
             Width="100" Height="100"/>
  </Canvas>
</Window>

The following code behind creates the MouseMove event handler. When the mouse pointer moves, the height and the width of the Ellipse are increased and decreased.

// raised when the mouse pointer moves. 
// Expands the dimensions of an Ellipse when the mouse moves. 
private void MouseMoveHandler(object sender, MouseEventArgs e)
{
    // Get the x and y coordinates of the mouse pointer.
    System.Windows.Point position = e.GetPosition(this);
    double pX = position.X;
    double pY = position.Y;

    // Sets the Height/Width of the circle to the mouse coordinates.
    ellipse.Width = pX;
    ellipse.Height = pY;
}

.NET Framework

Supported in: 4.5, 4, 3.5, 3.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

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