MouseWheelEventArgs Class

Definition

Namespace:

System.Windows.Input

Assembly:

PresentationCore.dll

Provides data for various events that report changes to the mouse wheel delta value of a mouse device.

public ref class MouseWheelEventArgs : System::Windows::Input::MouseEventArgs

public class MouseWheelEventArgs : System.Windows.Input.MouseEventArgs

type MouseWheelEventArgs = class
    inherit MouseEventArgs

Public Class MouseWheelEventArgs
Inherits MouseEventArgs

Inheritance

Object

EventArgs

RoutedEventArgs

InputEventArgs

MouseEventArgs

MouseWheelEventArgs

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

MouseWheelEventArgs is used with the following events:

• UIElement.MouseWheel

• ContentElement.MouseWheel

• Mouse.MouseWheel (attached event)

• UIElement.PreviewMouseWheel

• ContentElement.PreviewMouseWheel

• Mouse.PreviewMouseWheel (attached event)

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

This event is raised even for small mouse wheel movements. For some scenarios, it is appropriate to implement handlers that throttle small mouse wheel deltas by checking whether the delta exceeds a certain threshold. Otherwise, you might invoke your handler for cases where the mouse wheel delta was so small that any UI that is tied to the mouse wheel movement would not update. Exactly how you implement the threshold behavior in a handler and what that threshold should be is entirely implementation-specific.

Constructors

MouseWheelEventArgs(MouseDevice, Int32, Int32)

Initializes a new instance of the MouseWheelEventArgs class.

Properties

Delta	Gets a value that indicates the amount that the mouse wheel has changed.
Device	Gets the input device that initiated this event. (Inherited from InputEventArgs)
Handled	Gets or sets a value that indicates the present state of the event handling for a routed event as it travels the route. (Inherited from RoutedEventArgs)
LeftButton	Gets the current state of the left mouse button. (Inherited from MouseEventArgs)
MiddleButton	Gets the current state of the middle mouse button. (Inherited from MouseEventArgs)
MouseDevice	Gets the mouse device associated with this event. (Inherited from MouseEventArgs)
OriginalSource	Gets the original reporting source as determined by pure hit testing, before any possible Source adjustment by a parent class. (Inherited from RoutedEventArgs)
RightButton	Gets the current state of the right mouse button. (Inherited from MouseEventArgs)
RoutedEvent	Gets or sets the RoutedEvent associated with this RoutedEventArgs instance. (Inherited from RoutedEventArgs)
Source	Gets or sets a reference to the object that raised the event. (Inherited from RoutedEventArgs)
StylusDevice	Gets the stylus device associated with this event. (Inherited from MouseEventArgs)
Timestamp	Gets the time when this event occurred. (Inherited from InputEventArgs)
XButton1	Gets the current state of the first extended mouse button. (Inherited from MouseEventArgs)
XButton2	Gets the state of the second extended mouse button. (Inherited from MouseEventArgs)

Methods

Equals(Object)	Determines whether the specified object is equal to the current object. (Inherited from Object)
GetHashCode()	Serves as the default hash function. (Inherited from Object)
GetPosition(IInputElement)	Returns the position of the mouse pointer relative to the specified element. (Inherited from MouseEventArgs)
GetType()	Gets the Type of the current instance. (Inherited from Object)
InvokeEventHandler(Delegate, Object)	Invokes event handlers in a type-specific way, which can increase event system efficiency.
MemberwiseClone()	Creates a shallow copy of the current Object. (Inherited from Object)
OnSetSource(Object)	When overridden in a derived class, provides a notification callback entry point whenever the value of the Source property of an instance changes. (Inherited from RoutedEventArgs)
ToString()	Returns a string that represents the current object. (Inherited from Object)

See also

• MouseWheelDeltaForOneLine