Supports the page parser in building a control and the child controls it contains.
Namespace:
System.Web.UI
Assembly:
System.Web (in System.Web.dll)
Visual Basic (Declaration)
<AspNetHostingPermissionAttribute(SecurityAction.InheritanceDemand, Level := AspNetHostingPermissionLevel.Minimal)> _
<AspNetHostingPermissionAttribute(SecurityAction.LinkDemand, Level := AspNetHostingPermissionLevel.Minimal)> _
Public Class ControlBuilder
Dim instance As ControlBuilder
[AspNetHostingPermissionAttribute(SecurityAction.InheritanceDemand, Level = AspNetHostingPermissionLevel.Minimal)]
[AspNetHostingPermissionAttribute(SecurityAction.LinkDemand, Level = AspNetHostingPermissionLevel.Minimal)]
public class ControlBuilder
[AspNetHostingPermissionAttribute(SecurityAction::InheritanceDemand, Level = AspNetHostingPermissionLevel::Minimal)]
[AspNetHostingPermissionAttribute(SecurityAction::LinkDemand, Level = AspNetHostingPermissionLevel::Minimal)]
public ref class ControlBuilder
public class ControlBuilder
By default, every control on a page is associated with a default ControlBuilder class. During parsing, the ASP.NET page framework builds a tree of ControlBuilder objects corresponding to the tree of controls for the page. The ControlBuilder tree is then used to generate page code to create the control tree. In addition to child controls, the ControlBuilder defines the behavior of how the content within control tags is parsed. You can override this default behavior by defining your own custom control builder class. This is done by applying a ControlBuilderAttribute attribute to your control builder class as follows:
[ControlBuilderAttribute(typeof(ControlBuilderType))]
The following code example creates a Table control whose attributes and content are defined at the time the table is built. The following is the command line to use to build the executable.
[Visual Basic]
vbc /r:System.dll /r:System.Web.dll /r:System.Drawing.dll /t:library /out:myWebAppPath/Bin/vb_mycontrolbuilder.dll myControlBuilder.vb
[C#]
csc /t:library /out:myWebAppPath/Bin/cs_mycontrolbuilder.dll myControlBuilder.cs
Imports System
Imports System.Web
Imports System.Web.UI
Imports System.Web.UI.WebControls
Imports System.Collections
Imports System.Drawing
Imports System.Security.Permissions
Namespace CustomControls
<AspNetHostingPermission(SecurityAction.Demand, Level:=AspNetHostingPermissionLevel.Minimal)> _
Public Class MyTableCell
Inherits TableCell
Implements INamingContainer
End Class
<AspNetHostingPermission(SecurityAction.Demand, Level:=AspNetHostingPermissionLevel.Minimal)> _
Public Class MyCell
Inherits Control
Implements INamingContainer
' Class Name: MyCell.
' Declares the class for the child controls to be included in the control collection.
Private _id As String
Private _value As String
Private _backColor As Color
Public Property CellID() As String
Get
Return _id
End Get
Set(ByVal value As String)
_id = value
End Set
End Property
Public Property Text() As String
Get
Return _value
End Get
Set(ByVal value As String)
_value = value
End Set
End Property
Public Property BackColor() As Color
Get
Return _backColor
End Get
Set(ByVal value As Color)
_backColor = value
End Set
End Property
End Class
<AspNetHostingPermission(SecurityAction.Demand, Level:=AspNetHostingPermissionLevel.Minimal)> _
Public Class MyControlBuilderVB
Inherits ControlBuilder
Public Overrides Function GetChildControlType(ByVal tagName As String, ByVal attribs As IDictionary) As Type
' Allows TableRow without "runat=server" attribute to be added to the collection.
If (String.Compare(tagName, "mycell", True) = 0) Then
Return GetType(MyCell)
End If
Return Nothing
End Function
' Ignores literals between rows.
Public Overrides Sub AppendLiteralString(ByVal s As String)
' Ignores literals between rows.
End Sub
End Class
<AspNetHostingPermission(SecurityAction.Demand, Level:=AspNetHostingPermissionLevel.Minimal), ControlBuilderAttribute(GetType(MyControlBuilderVB))> _
Public Class MyVB_CustomControl
Inherits Control
Implements INamingContainer
' Class name: MyVB_CustomControl.
' Processes the element declarations within a control
' declaration. This builds the actual control.
' Custom control to build programmatically.
Private _table As Table
Private _cellObjects As New Hashtable()
' Variables that must contain the control attributes as defined in the Web page.
Private _rows As Integer
Private _columns As Integer
Private _title As String
' Rows property to be used as the attribute name in the Web page.
Public Property Rows() As Integer
Get
Return _rows
End Get
Set(ByVal value As Integer)
_rows = value
End Set
End Property
' Columns property to be used as the attribute name in the Web page.
Public Property Columns() As Integer
Get
Return _columns
End Get
Set(ByVal value As Integer)
_columns = value
End Set
End Property
' Title property to be used as the attribute name in the Web page
Public Property Title() As String
Get
Return _title
End Get
Set(ByVal value As String)
_title = value
End Set
End Property
Protected Sub createNewRow(ByVal rowNumber As Integer)
' Creates a row and adds it to the table.
Dim row As TableRow
row = New TableRow()
_table.Rows.Add(row)
' Creates a cell that contains text.
Dim y As Integer
For y = 0 To Columns - 1
appendCell(row, rowNumber, y)
Next y
End Sub 'createNewRow
Protected Sub appendCell(ByVal row As TableRow, ByVal rowNumber As Integer, ByVal cellNumber As Integer)
Dim cell As TableCell
Dim textbox As TextBox
cell = New TableCell()
textbox = New TextBox()
cell.Controls.Add(textbox)
textbox.ID = "r" + rowNumber.ToString() + "c" + cellNumber.ToString()
' Checks for the MyCell child object.
If Not (_cellObjects(textbox.ID) Is Nothing) Then
Dim cellLookup As MyCell
cellLookup = CType(_cellObjects(textbox.ID), MyCell)
textbox.Text = cellLookup.Text
textbox.BackColor = cellLookup.BackColor
Else
textbox.Text = "Row: " + rowNumber.ToString() + " Cell: " + cellNumber.ToString()
End If
row.Cells.Add(cell)
End Sub 'appendCell
' Called at runtime when a child object is added to the collection.
Protected Overrides Sub AddParsedSubObject(ByVal obj As Object)
Dim cell As MyCell = CType(obj, MyCell)
If Not (cell Is Nothing) Then
_cellObjects.Add(cell.CellID, cell)
End If
End Sub 'AddParsedSubObject
Protected Overrides Sub OnPreRender(ByVal e As EventArgs)
' Sub name: OnPreRender.
' Carries out changes affecting the control state and renders the resulting UI.
' Increases the number of rows if needed.
While _table.Rows.Count < Rows
createNewRow(_table.Rows.Count)
End While
' Checks that each row has the correct number of columns.
Dim i As Integer
For i = 0 To _table.Rows.Count - 1
While _table.Rows(i).Cells.Count < Columns
appendCell(_table.Rows(i), i, _table.Rows(i).Cells.Count)
End While
While _table.Rows(i).Cells.Count > Columns
_table.Rows(i).Cells.RemoveAt((_table.Rows(i).Cells.Count - 1))
End While
Next i
End Sub 'OnPreRender
<System.Security.Permissions.PermissionSetAttribute(System.Security.Permissions.SecurityAction.Demand, Name:="FullTrust")> _
Protected Overrides Sub CreateChildControls()
' Sub name: CreateChildControls.
' Adds the Table and the text controls to the control collection.
Dim [text] As LiteralControl
' Initializes the text control using the Title property.
[text] = New LiteralControl("<h5>" + Title + "</h5>")
Controls.Add([text])
_table = New Table()
Controls.Add(_table)
End Sub
End Class
End Namespace
using System;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Collections;
using System.Drawing;
using System.Security.Permissions;
namespace CustomControls
{
[AspNetHostingPermission(SecurityAction.Demand,
Level = AspNetHostingPermissionLevel.Minimal)]
public class MyTableCell : TableCell, INamingContainer { };
[AspNetHostingPermission(SecurityAction.Demand,
Level = AspNetHostingPermissionLevel.Minimal)]
public class MyCell
/*
* Class name: MyCell.
* Declares the class for the child controls to include in the control collection.
*/
{
string _id;
string _value;
Color _backColor;
public string CellID
{
get
{ return _id; }
set
{ _id = value; }
}
public string Text
{
get
{ return _value; }
set
{ _value = value; }
}
public Color BackColor
{
get
{ return _backColor; }
set
{ _backColor = value; }
}
};
[AspNetHostingPermission(SecurityAction.Demand,
Level = AspNetHostingPermissionLevel.Minimal)]
public class MyControlBuilder : ControlBuilder
{
public override Type GetChildControlType(string tagName, IDictionary attribs)
{
// Allows TableRow without "runat=server" attribute to be added to the collection.
if (String.Compare(tagName, "mycell", true) == 0)
return typeof(MyCell);
return null;
}
public override void AppendLiteralString(string s)
{
// Ignores literals between rows.
}
}
[AspNetHostingPermission(SecurityAction.Demand,
Level = AspNetHostingPermissionLevel.Minimal)]
[ControlBuilderAttribute(typeof(MyControlBuilder))]
public class MyCS_CustomControl : Control, INamingContainer
/*
* Class name: MyCS_CustomControl.
* Processes the element declarations within a control declaration.
* This builds the actual control.
*/
{
// Declares the custom control that must be built programmatically.
Table _table;
private String _title;
private int _rows;
private int _columns;
Hashtable _cellObjects = new Hashtable();
// Rows property to be used as the attribute name in the Web page.
public int Rows
{
get
{ return _rows; }
set
{ _rows = value; }
}
// Columns property to be used as the attribute name in the Web page.
public int Columns
{
get
{ return _columns; }
set
{ _columns = value; }
}
// Title property to be used as the attribute name in the Web page.
public string Title
{
get
{ return _title; }
set
{ _title = value; }
}
protected void createNewRow(int rowNumber)
{
// Creates a row and adds it to the table.
TableRow row;
row = new TableRow();
_table.Rows.Add(row);
// Creates a cell that contains text.
for (int y = 0; y < Columns; y++)
appendCell(row, rowNumber, y);
}
protected void appendCell(TableRow row, int rowNumber, int cellNumber)
{
TableCell cell;
TextBox textbox;
cell = new TableCell();
textbox = new TextBox();
cell.Controls.Add(textbox);
textbox.ID = "r" + rowNumber.ToString() + "c" + cellNumber.ToString();
// Checks for the MyCell child object.
if (_cellObjects[textbox.ID] != null)
{
MyCell cellLookup;
cellLookup = (MyCell)_cellObjects[textbox.ID];
textbox.Text = cellLookup.Text;
textbox.BackColor = cellLookup.BackColor;
}
else
textbox.Text = "Row: " + rowNumber.ToString() + " Cell: " +
cellNumber.ToString();
row.Cells.Add(cell);
}
// Called at runtime when a child object is added to the collection.
protected override void AddParsedSubObject(object obj)
{
MyCell cell = obj as MyCell;
if (cell != null)
{
_cellObjects.Add(cell.CellID, cell);
}
}
protected override void OnPreRender(EventArgs e)
/*
* Function name: OnPreRender.
* Carries out changes affecting the control state and renders the resulting UI.
*/
{
// Increases the number of rows if needed.
while (_table.Rows.Count < Rows)
{
createNewRow(_table.Rows.Count);
}
// Checks that each row has the correct number of columns.
for (int i = 0; i < _table.Rows.Count; i++)
{
while (_table.Rows[i].Cells.Count < Columns)
{
appendCell(_table.Rows[i], i, _table.Rows[i].Cells.Count);
}
while (_table.Rows[i].Cells.Count > Columns)
{
_table.Rows[i].Cells.RemoveAt(_table.Rows[i].Cells.Count - 1);
}
}
}
protected override void CreateChildControls()
/*
* Function name: CreateChildControls.
* Adds the Table and the text control to the control collection.
*/
{
LiteralControl text;
// Initializes the text control using the Title property.
text = new LiteralControl("<h5>" + Title + "</h5>");
Controls.Add(text);
_table = new Table();
_table.BorderWidth = 2;
Controls.Add(_table);
}
}
}
The following code example uses the previous custom control. In particular, it builds a table whose attributes and content are defined at run time. Notice that the values shown in the @ Register directive reflect the previous command line.
<%@ Page Language="VB" %>
<%@ Register TagPrefix="AspNetSamples" Assembly="vb_mycontrolbuilder" Namespace="CustomControls" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<script runat="server">
</script>
<html >
<head runat="server">
<title>ControlBuilder Example</title>
</head>
<body>
<form id="form1" runat="server">
<div>
<AspNetSamples:MyVB_CustomControl id="Custom1"
title="Auto-Generated Table"
columns="3"
rows="3"
runat="server">
<mycell cellid="r0c0" BackColor="red" text="red cell"></mycell>
<mycell cellid="r2c2" BackColor="green" text="green cell"></mycell>
</AspNetSamples:MyVB_CustomControl>
</div>
</form>
</body>
</html>
<%@ Page Language="C#" %>
<%@ Register TagPrefix="AspNetSamples" Assembly="cs_mycontrolbuilder" Namespace="CustomControls" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<script runat="server">
</script>
<html >
<head runat="server">
<title>ControlBuilder Example</title>
</head>
<body>
<form id="form1" runat="server">
<div>
<AspNetSamples:MyCS_CustomControl id="Custom1"
title="Auto-Generated Table"
columns="3"
rows="3"
runat="server">
<mycell cellid="r0c0" BackColor="red" text="red cell"></mycell>
<mycell cellid="r2c2" BackColor="green" text="green cell"></mycell>
</AspNetSamples:MyCS_CustomControl>
</div>
</form>
</body>
</html>
System..::.Object
System.Web.UI..::.ControlBuilder
System.Web.UI..::.DataSourceControlBuilder
System.Web.UI.HtmlControls..::.HtmlEmptyTagControlBuilder
System.Web.UI.HtmlControls..::.HtmlHeadBuilder
System.Web.UI.HtmlControls..::.HtmlSelectBuilder
System.Web.UI.MobileControls..::.DeviceSpecificChoiceControlBuilder
System.Web.UI.MobileControls..::.DeviceSpecificControlBuilder
System.Web.UI.MobileControls..::.MobileControlBuilder
System.Web.UI..::.ObjectTagBuilder
System.Web.UI..::.SkinBuilder
System.Web.UI..::.TemplateBuilder
System.Web.UI..::.UserControlControlBuilder
System.Web.UI.WebControls..::.HyperLinkControlBuilder
System.Web.UI.WebControls..::.LabelControlBuilder
System.Web.UI.WebControls..::.LinkButtonControlBuilder
System.Web.UI.WebControls..::.ListItemControlBuilder
System.Web.UI.WebControls..::.LiteralControlBuilder
System.Web.UI.WebControls..::.MultiViewControlBuilder
System.Web.UI.WebControls..::.PlaceHolderControlBuilder
System.Web.UI.WebControls..::.TableCellControlBuilder
System.Web.UI.WebControls..::.TextBoxControlBuilder
System.Web.UI.WebControls..::.WizardStepControlBuilder
System.Web.UI.WebControls..::.XmlBuilder
Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.
Windows 7, Windows Vista, Windows XP SP2, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP Starter Edition, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003, Windows Server 2000 SP4, Windows Millennium Edition, Windows 98
The .NET Framework and .NET Compact Framework do not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.
.NET Framework
Supported in: 3.5, 3.0, 2.0, 1.1, 1.0
Reference