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MouseWheelEventArgs.Delta Property

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Definition

Namespace:
System.Windows.Input
Assembly:
PresentationCore.dll

Gets a value that indicates the amount that the mouse wheel has changed.

public:
 property int Delta { int get(); };
public int Delta { get; }
member this.Delta : int
Public ReadOnly Property Delta As Integer

Property Value

Int32

The amount the wheel has changed. This value is positive if the mouse wheel is rotated in an upward direction (away from the user) or negative if the mouse wheel is rotated in a downward direction (toward the user).

Examples

The following example moves a TextBox up if the mouse wheel Delta is positive and moves the TextBox down if the mouse wheel Delta is negative. The TextBox is attached to a Canvas.

// 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);
        }
    }
}

' Moves the TextBox named box when the mouse wheel is rotated.
' The TextBox is on a Canvas named MainCanvas.
Private Sub MouseWheelHandler(ByVal sender As Object, ByVal e As MouseWheelEventArgs)
    ' If the mouse wheel delta is positive, move the box up.
    If e.Delta > 0 Then
        If Canvas.GetTop(box) >= 1 Then
            Canvas.SetTop(box, Canvas.GetTop(box) - 1)
        End If
    End If

    ' If the mouse wheel delta is negative, move the box down.
    If e.Delta < 0 Then
        If (Canvas.GetTop(box) + box.Height) <= MainCanvas.Height Then
            Canvas.SetTop(box, Canvas.GetTop(box) + 1)
        End If
    End If

End Sub

Remarks

The effective upper and lower ranges of this value potentially come from device implementations or other callers that raised the event, and are therefore not defined.

Applies to

See also