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UIElement.MouseEnter Event

Occurs when the mouse pointer enters the bounds of this element.

Namespace:  System.Windows
Assembly:  PresentationCore (in PresentationCore.dll)
XMLNS for XAML: http://schemas.microsoft.com/winfx/2006/xaml/presentation, http://schemas.microsoft.com/netfx/2007/xaml/presentation

public event MouseEventHandler MouseEnter
<object MouseEnter="MouseEventHandler" .../>

Implements

IInputElement.MouseEnter

Identifier field

MouseEnterEvent

Routing strategy

Direct

Delegate

MouseEventHandler

  • Override OnMouseEnter to implement class handling for this event in derived classes.

MouseEnter is a routed event that uses the direct event handling routing strategy. Direct routed events are not raised along a route; instead, they are handled in the same element where they are raised. However, they do enable other aspects of routed event behavior, such as event triggers in styles.

Although MouseEnter tracks when the mouse pointer enters the bounds of an element, this event more literally reports that the IsMouseOver property value has changed from false to true on this element.

This event creates an alias for the Mouse.MouseEnter attached event for this class, so that MouseEnter is part of the class members list when UIElement is inherited as a base element. Event handlers that are attached to the MouseEnter event are attached to the underlying Mouse.MouseEnter attached event and receive the same event data instance.

A Button (or any ButtonBase derived class) has native handling for a KeyDown event when the button has focus, and the pressed key is the space bar. The native handling raises the Click event with the button as the source, and also captures the mouse, even though the mouse pointer does not appear to move. As a result of the mouse capture, a MouseEnter event is also raised with the button as the source. In general, if an element captures the mouse, then MouseEnter is raised, as well as GotMouseCapture and possibly other control-specific events.

This example shows how to change the color of an element as the mouse pointer enters and leaves the area occupied by the element.

This example consists of a Extensible Application Markup Language (XAML) file and a code-behind file.

NoteNote

This example demonstrates how to use events, but the recommended way to achieve this same effect is to use a Trigger in a style. For more information, see Styling and Templating.

The following XAML creates the user interface, which consists of Border around a TextBlock, and attaches the MouseEnter and MouseLeave event handlers to the Border.

<StackPanel>
  <Border MouseEnter="OnMouseEnterHandler"
          MouseLeave="OnMouseLeaveHandler"
          Name="border1" Margin="10"
          BorderThickness="1"
          BorderBrush="Black"
          VerticalAlignment="Center"
          Width="300" Height="100">
    <Label Margin="10" FontSize="14"
           HorizontalAlignment="Center">Move Cursor Over Me</Label>
  </Border>
</StackPanel>

The following code behind creates the MouseEnter and MouseLeave event handlers. When the mouse pointer enters the Border, the background of the Border is changed to red. When the mouse pointer leaves the Border, the background of the Border is changed back to white.

public partial class Window1 : Window
{
    public Window1()
    {
        InitializeComponent();
    }

    // raised when mouse cursor enters the area occupied by the element 
    void OnMouseEnterHandler(object sender, MouseEventArgs e)
    {
        border1.Background = Brushes.Red;
    }

    // raised when mouse cursor leaves the area occupied by the element 
    void OnMouseLeaveHandler(object sender, MouseEventArgs e)
    {
        border1.Background = Brushes.White;
    }
}

.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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