Section 8.2. Common Event Reference

8.2. Common Event Reference

Elements deriving from UIElement inherit a set of common events. Events are used in XAML to specify the codebehind handler that will be executed when the specified event is raised. All events can be assigned a codebehind handler using the following syntax:

 <Element Name="ElementName" EventName="CodeBehindHandler" /> 

Elements specifying a codebehind handler must declare the Name attribute in order to be referenced in the codebehind class. Examples 8-2 and 8-3 demonstrate the event-handling code in C# and VisualBasic, respectively, which is executed when the mouse cursor enters or leaves the Button declared in Example 8-4.

Example 8-2. C# implementation of event handlers

 public partial class MouseEnterMouseLeave {     void MouseEnterHandler (object sender, MouseEventArgs e)     {         MyButton .Background=Brushes.Red;         MyButton .Content="Mouse is over me ";     }     void MouseLeaveHandler (object sender, MouseEventArgs e)     {         MyButton .Background=Brushes.White;         MyButton .Content="Mouse is not over me ";     } } 

Example 8-3. VisualBasic implementation of event handlers

 Partial Public Class MouseEnterMouseLeave     Sub MouseEnterHandler (ByVal sender as Object, ByVal e As MouseEventArgs         MyButton .Background = Brushes.Red         MyButton .Content = "Mouse is over me "     End Sub     Sub MouseLeaveHandler (ByVal sender As Object, ByVal e as MouseEventArgs         MyButton .Background = Brushes.White         MyButton .Content = "Mouse is not over me "     End Sub End Class 

Example 8-4. XAML declaration of event handlers for Button

 <StackPanel     xmlns="http://schemas.microsoft.com/winfx/avalon/2005"     xmlns:x="http://schemas.microsoft.com/winfx/xaml/2005"     x :     <Button         Content="Mouse is not over me "         MouseEnter="MouseEnterHandler "         MouseLeave="MouseLeaveHandler "         Name="MyButton " /> </StackPanel> 

The following events are common to all UIElement-derived elements. Events specific to the element are listed with the element description. Events are fully detailed in Chapter 12, along with a more thorough exploration of the event subsystem.

• DragEnter

• DragLeave

• DragOver

• Drop

• GotFocus

• IsVisibleChanged

• IsEnableChanged

• IsFocusChanged

• KeyUp

• KeyDown

• LayoutUpdated

• LostFocus

• MouseEnter

• MouseLeave

• MouseMove

• MouseLeftButtonDown

• MouseLeftButtonUp

• MouseRightButtonDown

• MouseRightButtonUp

• PreviewDragOver

• PreviewDragEnter

• PreviewDragLeave

• PreviewDrop

• PreviewKeyUp

• PreviewKeyDown

• PreviewMouseLeftButtonDown

• PreviewMouseLeftButtonUp

• PreviewMouseRightButtonDown

• PreviewMouseRightButtonUp

• PreviewMouseMove