ASP.NET.in.a.Nutshell.Second.Edition [Electronic resources]

The Control class defines properties, methods, and events that all server controls in ASP.NET require. ASP.NET controls do not inherit directly from this class; instead, they inherit from either the System.Web.UI.HtmlControls.HtmlControl or the System.Web.UI.WebControls.WebControl class, both of which inherit from the Control class. Similarly, the Page and UserControl classes inherit from TemplateControl, which inherits from this class.

The Control class contains many of the typical members you would expect in a control, including properties that reference the root of the control tree (Page) and a collection of contained controls (Controls). The EnableViewState property determines whether ASP.NET maintains the control's state automatically by using a hidden field. The ViewState property provides the StateBag collection of state information.

Most Control methods are used transparently by the ASP.NET framework, such as Render( ), which generates the HTML output of a control, and LoadViewState( ) and SaveViewState( ), which manage view state automatically. One interesting method is DataBind( ), which binds controls to arrays or data tables. Third party controls can also extend these methods.

You can inherit from the Control class to create a simple ASP.NET control. Override the Render( ) method so that the control can generate its own output by using the supplied HtmlTextWriter. If you are creating a composite control, you must also override the CreateChildControls( ) method. Use this method to instantiate new server-based ASP.NET controls or LiteralControl objects and add them to the collection of child controls by using the Add( ) method. If you need to access child controls from another procedure, and you are not sure if they have been created yet, you can use the EnsureChildControls( ) method, which automatically calls CreateChildControls( ), if needed. You should also implement the INamingContainer interface to ensure that child controls are created in a distinct namespace.

Usually, it is easier to derive from System.Web.UI.WebControls.WebControl when creating a custom control, as this class provides basic style and color options and manages the state for these properties automatically. If your control does not provide user interface, you may want to derive from the more basic Control class.

public class 
Control  : System.ComponentModel.IComponent, IDisposable,
 IParserAccessor, IDataBindingsAccessor {
// Public Constructors
public 
Control ( );
// Public Instance Properties
public Control 
BindingContainer {get; }
public virtual string 
ClientID {get; }
public virtual ControlCollection 
Controls {get; }
public virtual bool 
EnableViewState {set; get; }
public virtual string 
ID {set; get; }
public virtual Control 
NamingContainer {get; }
public virtual Page 
Page {set; get; }
public virtual Control 
Parent {get; }
public ISite 
Site {set; get; } // implements System.ComponentModel.IComponent
public virtual string 
TemplateSourceDirectory {get; }
public virtual string 
UniqueID {get; }
public virtual bool 
Visible {set; get; }
// Protected Instance Properties
protected bool 
ChildControlsCreated {set; get; }
protected virtual HttpContext 
Context {get; }
protected EventHandlerList 
Events {get; }
protected bool 
HasChildViewState {get; }
protected bool 
IsTrackingViewState {get; }
protected virtual StateBag 
ViewState {get; }
protected virtual bool 
ViewStateIgnoresCase {get; }
// Public Instance Methods
public virtual void 
DataBind ( );
public virtual void 
Dispose ( );                   // implements IDisposable
public virtual Control 
FindControl (string 
id );
public virtual bool 
HasControls ( );
public void 
RenderControl (HtmlTextWriter 
writer );
public string 
ResolveUrl (string 
relativeUrl );
public void 
SetRenderMethodDelegate (RenderMethod 
renderMethod );
// Protected Instance Methods
protected internal virtual void 
AddedControl (Control 
control , int 
index );
protected virtual void 
AddParsedSubObject (object 
obj );       // implements IParserAccessor
protected void 
BuildProfileTree (string 
parentId , bool 
calcViewState );
protected void 
ClearChildViewState ( );
protected virtual void 
CreateChildControls ( );
protected virtual ControlCollection 
CreateControlCollection ( );
protected virtual void 
EnsureChildControls ( );
protected virtual Control 
FindControl (string 
id , int 
pathOffset );
protected bool 
IsLiteralContent ( );
protected virtual void 
LoadViewState (object 
savedState );
protected string 
MapPathSecure (string 
virtualPath );
protected virtual bool 
OnBubbleEvent (object 
source , EventArgs 
args );
protected virtual void 
OnDataBinding (EventArgs 
e );
protected virtual void 
OnInit (EventArgs 
e );
protected virtual void 
OnLoad (EventArgs 
e );
protected virtual void 
OnPreRender (EventArgs 
e );
protected virtual void 
OnUnload (EventArgs 
e );
protected void 
RaiseBubbleEvent (object 
source , EventArgs 
args );
protected internal virtual void 
RemovedControl (Control 
control );
protected virtual void 
Render (HtmlTextWriter 
writer );
protected virtual void 
RenderChildren (HtmlTextWriter 
writer );
protected virtual object 
SaveViewState ( );
protected virtual void 
TrackViewState ( );
// Events
public event EventHandler 
DataBinding ;
public event EventHandler 
Disposed ;              // implements System.ComponentModel.IComponent
public event EventHandler 
Init ;
public event EventHandler 
Load ;
public event EventHandler 
PreRender ;
public event EventHandler 
Unload ;
}

Subclasses

Multiple types

Returned By

BuildMethod.{EndInvoke( ), Invoke( )}, ControlCollection.{Owner, this}, System.Web.UI.Design.ControlParser.ParseControl( ), DesignTimeTemplateParser.ParseControl( ), System.Web.UI.MobileControls.Form.ControlToPaginate, PartialCachingControl.CachedControl, TemplateControl.{LoadControl( ), ParseControl( )}, System.Web.UI.WebControls.CheckBoxList.FindControl( )

Passed To

Multiple types