ControlBuilderAttribute Class
Definition
Important
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Specifies a ControlBuilder class for building a custom control within the ASP.NET parser. This class cannot be inherited.
public ref class ControlBuilderAttribute sealed : Attribute[System.AttributeUsage(System.AttributeTargets.Class)]
public sealed class ControlBuilderAttribute : Attribute[<System.AttributeUsage(System.AttributeTargets.Class)>]
type ControlBuilderAttribute = class
inherit AttributePublic NotInheritable Class ControlBuilderAttribute
Inherits Attribute- Inheritance
- Attributes
Examples
The following code example creates a customized selection list that is used to display a message based on the SelectedIndex and the Message values defined at run time. The following command line is used to build the executable.
vbc /r:System.dll /r:System.Web.dll /r:System.Drawing.dll /t:library /out:myWebAppPath/Bin/vb_MyControlBuilderAtt.dll ControlBuilderAtt.vb
csc /t:library /out:myWebAppPath/Bin/cs_MyControlBuilderAtt.dll ControlBuilderAtt.cs
/* File name: controlBuilderAttribute.cs. */
using System;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Collections;
namespace CustomControls
{
public class MyCS_Item : Control
/* Class name: MyCS_Item.
* Defines the child control class.
*/
{
private String _message;
public String Message
{
get
{
return _message;
}
set
{
_message = value;
}
}
}
public class CustomParseControlBuilder : ControlBuilder
/* Class name: CustomParserControlBuilder.
* Defines the functions and data to be used in building custom controls.
* This class is referenced using the ControlBuilderAttribute class. See class below.
*/
{
[System.Security.Permissions.PermissionSet(System.Security.Permissions.SecurityAction.Demand, Name="FullTrust")]
public override Type GetChildControlType(String tagName, IDictionary attributes)
{
if (String.Compare(tagName, "customitem", true) == 0)
{
return typeof(MyCS_Item);
}
return null;
}
}
[
ControlBuilderAttribute(typeof(CustomParseControlBuilder))
]
public class MyCS_CustomParse : Control
/* Class name: MyCS_CustomParse.
* Performs custom parsing of a MyCS_CustomParse control type
* child control.
* If the child control is of the allowed type, it is added to an
* array list. This list is accessed, using the container control attribute
* SelectedIndex, to obtain the related child control Message attribute to be displayed.
*/
{
private ArrayList _items = new ArrayList();
private int _selectedIndex = 0;
public int SelectedIndex
{
get
{
return _selectedIndex;
}
set
{
_selectedIndex = value;
}
}
[System.Security.Permissions.PermissionSet(System.Security.Permissions.SecurityAction.Demand, Name="FullTrust")]
protected override void AddParsedSubObject(Object obj)
/* Function name: AddParsedSubObject.
* Updates the array list with the allowed child objects.
* This function is called during the parsing of the child controls and
* after the GetChildControlType function defined in the associated control
* builder class.
*/
{
if (obj is MyCS_Item)
{
_items.Add(obj);
}
}
[System.Security.Permissions.PermissionSet(System.Security.Permissions.SecurityAction.Demand, Name="FullTrust")]
protected override void Render(HtmlTextWriter output)
/* Function name: Render.
* Establishes the rules to render the built control. In this case, a message is
* rendered that is a function of the parent control SelectedIndex attribute and
* the related child Message attribute.
*/
{
if (SelectedIndex < _items.Count)
{
output.Write("<span style='background-color:aqua; color:red; font:8pt tahoma, verdana;'><b>" +
((MyCS_Item) _items[SelectedIndex]).Message + "</b></span>" );
}
}
}
}
'File name: controlBuilderAttribute.vb.
Imports System.Web
Imports System.Web.UI
Imports System.Web.UI.WebControls
Imports System.Collections
Namespace CustomControls
Public Class MyVB_Item: Inherits Control
Private _message As String
Public Property Message() As String
Get
Return _message
End Get
Set
_message = value
End Set
End Property
End Class
Public Class VB_CustomParseControlBuilder: Inherits ControlBuilder
<System.Security.Permissions.PermissionSetAttribute(System.Security.Permissions.SecurityAction.Demand, Name:="FullTrust")> _
Public Overrides Function GetChildControlType(TagName As String, attributes As IDictionary) As Type
If (TagName = "customitem") Then
Return GetType(CustomControls.MyVB_Item)
End If
Return Nothing
End Function 'GetChildControlType
End Class
<ControlBuilderAttribute(GetType(VB_CustomParseControlBuilder))> Public Class MyVB_CustomParse: Inherits Control
Private _items As New ArrayList
Private _selectedIndex As Integer = 0
Public Property SelectedIndex() As Integer
Get
Return _selectedIndex
End Get
Set
_selectedIndex = value
End Set
End Property
<System.Security.Permissions.PermissionSetAttribute(System.Security.Permissions.SecurityAction.Demand, Name:="FullTrust")> _
Protected Overrides Sub AddParsedSubObject(obj As Object)
If TypeOf obj Is MyVB_Item Then
_items.Add(obj)
End If
End Sub
<System.Security.Permissions.PermissionSetAttribute(System.Security.Permissions.SecurityAction.Demand, Name:="FullTrust")> _
Protected Overrides Sub Render(output As HtmlTextWriter)
output.Write(("<span style='background-color:aqua; color:red; font:8pt tahoma, verdana;'><b>" + CType(_items(SelectedIndex), MyVB_Item).Message + "</b></span>"))
End Sub
End Class
End Namespace 'CustomControls
The following example uses the custom control defined above. In particular, it assigns the SelectedIndex and Message values at run time to determine the message to be rendered. Notice that the values shown in the Register directive reflect the previous command line.
<%@ Register TagPrefix="custom" Assembly="myControlBuilderAtt" Namespace="CustomControls" %>
<h4>Using ControlBuilderAttribute Class<h4>
<form runat="server">
<custom:MyVB_CustomParse SelectedIndex="3" runat=server>
<customitem Message="Visual Basic version. Item One selected"/>
<customitem Message="Visual Basic version. Item Two selected"/>
<customitem Message="Visual Basic version. Item Three selected"/>
<customitem Message="Visual Basic version. Item Four selected"/>
</custom:MyVB_CustomParse>
</form>
<%@ Register TagPrefix="custom" Assembly="myControlBuilderAtt" Namespace="CustomControls" %>
<h4>Using ControlBuilderAttribute Class<h4>
<form runat="server">
<custom:MyCS_CustomParse SelectedIndex="2" runat=server>
<customitem Message="C# version. Item One selected"/>
<customitem Message="C# version. Item Two selected"/>
<customitem Message="C# version. Item Three selected"/>
<customitem Message="C# version. Item Four selected"/>
</custom:MyCS_CustomParse>
</form>
Remarks
This attribute specifies the builder Type to be used to create a custom control as shown in the following code:
[ControlBuilderAttribute(typeof(ControlBuilderType))]
Constructors
| ControlBuilderAttribute(Type) |
Specifies the control builder for a custom control. |
Fields
| Default |
Specifies the new ControlBuilderAttribute object. By default, the new object is set to null. This field is read-only. |
Properties
| BuilderType |
Gets the Type of the control associated with the attribute. This property is read-only. |
| TypeId |
When implemented in a derived class, gets a unique identifier for this Attribute. (Inherited from Attribute) |
Methods
| Equals(Object) |
Gets a value indicating whether the current ControlBuilderAttribute is identical to the specified object. |
| GetHashCode() |
Returns the hash code of the ControlBuilderAttribute object. |
| GetType() |
Gets the Type of the current instance. (Inherited from Object) |
| IsDefaultAttribute() |
Determines whether the current control builder is the default. |
| Match(Object) |
When overridden in a derived class, returns a value that indicates whether this instance equals a specified object. (Inherited from Attribute) |
| MemberwiseClone() |
Creates a shallow copy of the current Object. (Inherited from Object) |
| ToString() |
Returns a string that represents the current object. (Inherited from Object) |
Explicit Interface Implementations
| _Attribute.GetIDsOfNames(Guid, IntPtr, UInt32, UInt32, IntPtr) |
Maps a set of names to a corresponding set of dispatch identifiers. (Inherited from Attribute) |
| _Attribute.GetTypeInfo(UInt32, UInt32, IntPtr) |
Retrieves the type information for an object, which can be used to get the type information for an interface. (Inherited from Attribute) |
| _Attribute.GetTypeInfoCount(UInt32) |
Retrieves the number of type information interfaces that an object provides (either 0 or 1). (Inherited from Attribute) |
| _Attribute.Invoke(UInt32, Guid, UInt32, Int16, IntPtr, IntPtr, IntPtr, IntPtr) |
Provides access to properties and methods exposed by an object. (Inherited from Attribute) |
