ResizableControl is an extender that attaches to any element on a web page and allows the user to resize that control with a handle that attaches to lower-right corner of the control. The resize handle lets the user resize the element as if it were a window. The appearance of the resize handle can be specified by the page designer with a CSS style. The content within the element can use CSS styles to automatically resize to fit the new dimensions. Alternatively, ResizableControl exposes two events (onresizing and onresize) that the page designer can attach custom script to in order to enable more complex layout logic. Element dimensions are preserved across postbacks to the server and "size" properties accessible on both the client and server can be used to enable custom resize behaviors. ResizableControl can optionally limit the maximum and minimum width and height of the target control so that resizing can be constrained by the page author (for example, to limit scrolling to only the horizontal dimension).

The controls above are initialized with code like this. The italic properties are optional:

<ajaxToolkit:ResizableControlExtender ID="RCE" runat="server"

    TargetControlID="PanelImage"

    HandleCssClass="handleImage"

    ResizableCssClass="resizingImage"

    MinimumWidth="50"

    MinimumHeight="20"

    MaximumWidth="260"

    MaximumHeight="130"

    OnClientResize="OnClientResizeImage"

    HandleOffsetX="3"

    HandleOffsetY="3" />

    * TargetControlID - The ID of the element that becomes resizable

    * HandleCssClass - The name of the CSS class to apply to the resize handle

    * ResizableCssClass - The name of the CSS class to apply to the element when resizing

    * MinimumWidth/MinimumHeight - Minimum dimensions of the resizable element

    * MaximumWidth/MaximumHeight - Maximum dimensions of the resizable element

    * OnClientResizeBegin - Event fired when the element starts being resized

    * OnClientResizing - Event fired as the element is being resized

    * OnClientResize - Event fired when the element has been resized

    * HandleOffsetX/HandleOffsetY - Offsets to apply to the location of the resize handle