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Thumb.DragDelta Event

Occurs one or more times as the mouse changes position when a Thumb control has logical focus and mouse capture.

Namespace: System.Windows.Controls.Primitives
Assembly: PresentationFramework (in presentationframework.dll)
XML Namespace:  http://schemas.microsoft.com/winfx/2006/xaml/presentation

public event DragDeltaEventHandler DragDelta
/** @event */
public void add_DragDelta (DragDeltaEventHandler value)

/** @event */
public void remove_DragDelta (DragDeltaEventHandler value)

In JScript, you can handle the events defined by a class, but you cannot define your own.
<object DragDelta="DragDeltaEventHandler" .../>

Identifier Field

DragDeltaEvent

Routing Strategy

Bubbling

Delegate

DragDeltaEventHandler

The Thumb control receives focus and mouse capture when the user presses the left mouse button while pausing the mouse pointer over the Thumb control. The Thumb control loses mouse capture when the user releases the left mouse button, or when the CancelDrag method is called.

A new DragDelta event occurs each time the mouse position moves on the screen. Therefore, this event can be raised multiple times without a limit when a Thumb control has mouse capture.

The following example shows how to assign an event handler for the DragDelta event to a Thumb control, and how to define the event handler. For the complete sample, see Drag Functionality Sample.

<Thumb Name="myThumb" Canvas.Left="80" Canvas.Top="80" Background="Blue" 
      Width="20" Height="20" DragDelta="onDragDelta" 
      DragStarted="onDragStarted" DragCompleted="onDragCompleted"
      />

void onDragDelta(object sender, DragDeltaEventArgs e)
{
    //Move the Thumb to the mouse position during the drag operation
    double yadjust = myCanvasStretch.Height + e.VerticalChange;
    double xadjust = myCanvasStretch.Width + e.HorizontalChange;
    if ((xadjust >= 0) && (yadjust >= 0))
    {
        myCanvasStretch.Width = xadjust;
        myCanvasStretch.Height = yadjust;
        Canvas.SetLeft(myThumb, Canvas.GetLeft(myThumb) +
                                e.HorizontalChange);
        Canvas.SetTop(myThumb, Canvas.GetTop(myThumb) +
                                e.VerticalChange);
        changes.Text = "Size: " +
                        myCanvasStretch.Width.ToString() +
                         ", " +
                        myCanvasStretch.Height.ToString();
    }
}

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

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