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title, ms.date, dev_langs, helpviewer_keywords, ms.assetid
| title | ms.date | dev_langs | helpviewer_keywords | ms.assetid | |||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| How to: Resize a Canvas by Using a Thumb | 03/30/2017 |
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7dc9f435-726c-4d4d-be41-eb24cfe17bef |
How to: Resize a Canvas by Using a Thumb
This example shows how to use a xref:System.Windows.Controls.Primitives.Thumb control to resize a xref:System.Windows.Controls.Canvas control.
Example
The xref:System.Windows.Controls.Primitives.Thumb control provides drag functionality that can be used to move or resize controls by monitoring the xref:System.Windows.Controls.Primitives.Thumb.DragStarted, xref:System.Windows.Controls.Primitives.Thumb.DragDelta and xref:System.Windows.Controls.Primitives.Thumb.DragCompleted events of the xref:System.Windows.Controls.Primitives.Thumb.
The user begins a drag operation by pressing the left mouse button when the mouse pointer is paused on the xref:System.Windows.Controls.Primitives.Thumb control. The drag operation continues as long as the left mouse button remains pressed. During the drag operation, the xref:System.Windows.Controls.Primitives.Thumb.DragDelta can occur more than once. Each time it occurs, the xref:System.Windows.Controls.Primitives.DragDeltaEventArgs class provides the change in position that corresponds to the change in mouse position. When the user releases the left mouse button, the drag operation is finished. The drag operation only provides new coordinates; it does not automatically reposition the xref:System.Windows.Controls.Primitives.Thumb.
The following example shows a xref:System.Windows.Controls.Primitives.Thumb control that is the child element of a xref:System.Windows.Controls.Canvas control. The event handler for its xref:System.Windows.Controls.Primitives.Thumb.DragDelta event provides the logic to move the xref:System.Windows.Controls.Primitives.Thumb and resize the xref:System.Windows.Controls.Canvas. The event handlers for the xref:System.Windows.Controls.Primitives.Thumb.DragStarted and xref:System.Windows.Controls.Primitives.Thumb.DragCompleted event change the color of the xref:System.Windows.Controls.Primitives.Thumb during a drag operation. The following example defines the xref:System.Windows.Controls.Primitives.Thumb.
[!code-xamlThumb#thumb]
The following example shows the xref:System.Windows.Controls.Primitives.Thumb.DragDelta event handler that moves the xref:System.Windows.Controls.Primitives.Thumb and resizes the xref:System.Windows.Controls.Canvas in response to a mouse movement.
[!code-csharpThumb#2]
The following example shows the xref:System.Windows.Controls.Primitives.Thumb.DragStarted event handler.
[!code-csharpThumb#DragStartedHandler] [!code-vbThumb#DragStartedHandler]
The following example shows the xref:System.Windows.Controls.Primitives.Thumb.DragCompleted event handler.
[!code-csharpThumb#DragCompletedHandler] [!code-vbThumb#DragCompletedHandler]
For the complete sample, see Thumb Drag Functionality Sample.