Information
The topic you requested is included in another documentation set. For convenience, it's displayed below. Choose Switch to see the topic in its original location.
0 out of 1 rated this helpful - Rate this topic

MouseWheelEventHandler Delegate

Represents the method that will handle the MouseWheel event.

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

public delegate void MouseWheelEventHandler (
	Object sender,
	MouseWheelEventArgs e
)
/** @delegate */
public delegate void MouseWheelEventHandler (
	Object sender, 
	MouseWheelEventArgs e
)
In XAML, you can use delegates but you cannot define your own.

Parameters

sender

The source of the event.

e

The event data.

The MouseWheelEventHandler is used with the following events: MouseWheel and PreviewMouseWheel.

The Delta property is positive if the mouse wheel is moved forward (away from the user) or negative if the mouse wheel is moved downward (toward the user).

When you create a MouseWheelEventHandler delegate, you identify the method that will handle the event. To associate the event with your event handler, add an instance of the delegate to the event. The event handler is called whenever the event occurs, unless you remove the delegate. For more information about event-handler delegates, see Events and Delegates.

The following example moves a TextBox, which is attached to a Canvas, upward if the mouse wheel Delta is positive and moves the TextBox downward if the mouse wheel Delta is negative.

// Moves the TextBox named box when the mouse wheel is rotated.
// The TextBox is on a Canvas named MainCanvas.
private void MouseWheelHandler(object sender, MouseWheelEventArgs e)
{
    // If the mouse wheel delta is positive, move the box up.
    if (e.Delta > 0)
    {
        if (Canvas.GetTop(box) >= 1)
        {
            Canvas.SetTop(box, Canvas.GetTop(box) - 1);
        }
    }

    // If the mouse wheel delta is negative, move the box down.
    if (e.Delta < 0)
    {
        if ((Canvas.GetTop(box) + box.Height) <= (MainCanvas.Height))
        {
            Canvas.SetTop(box, Canvas.GetTop(box) + 1);
        }
    }

}

Windows 98, Windows Server 2000 SP4, Windows CE, Windows Millennium Edition, Windows Mobile for Pocket PC, Windows Mobile for Smartphone, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition

The Microsoft .NET Framework 3.0 is supported on Windows Vista, Microsoft Windows XP SP2, and Windows Server 2003 SP1.

.NET Framework

Supported in: 3.0
Did you find this helpful?
(1500 characters remaining)
Thank you for your feedback

Community Additions

Show:
© 2014 Microsoft. All rights reserved.