ControlBuilder Class

Reference

Definition

Namespace:: System.Web.UI

Assembly:: System.Web.dll

Important

Some information relates to prerelease product that may be substantially modified before it’s released. Microsoft makes no warranties, express or implied, with respect to the information provided here.

Supports the page parser in building a control and the child controls it contains.

public ref class ControlBuilder

public class ControlBuilder

type ControlBuilder = class

Public Class ControlBuilder

Inheritance: Object
ControlBuilder

Derived: System.Web.UI.CodeStatementBuilder

System.Web.UI.DataSourceControlBuilder

System.Web.UI.HtmlControls.HtmlEmptyTagControlBuilder

System.Web.UI.HtmlControls.HtmlHeadBuilder

System.Web.UI.HtmlControls.HtmlSelectBuilder

More…

Examples

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.

vbc /r:System.dll /r:System.Web.dll /r:System.Drawing.dll /t:library /out:myWebAppPath/Bin/vb_mycontrolbuilder.dll myControlBuilder.vb

csc /t:library /out:myWebAppPath/Bin/cs_mycontrolbuilder.dll myControlBuilder.cs

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);
        }
    }
}

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


        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

        ' 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


        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


        <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

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.

ASP.NET (C#)

<%@ 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 xmlns="http://www.w3.org/1999/xhtml" >
<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>

<%@ 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 xmlns="http://www.w3.org/1999/xhtml" >
<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>

Remarks

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))]

Constructors

ControlBuilder()

Initializes a new instance of the ControlBuilder class.

Fields

DesignerFilter

Represents the "__designer" literal string.

Properties

BindingContainerBuilder	Gets the control builder that corresponds to the binding container for the control that this builder creates.
BindingContainerType	Gets the type of the binding container for the control that this builder creates.
ComplexPropertyEntries	Gets a collection of complex property entries.
ControlType	Gets the Type for the control to be created.
CurrentFilterResolutionService	Gets an IFilterResolutionService object that is used to manage device-filter related services when parsing and persisting controls in the designer.
DeclareType	Gets the type that will be used by code generation to declare the control.
FChildrenAsProperties	Gets a value that determines whether the control has a ParseChildrenAttribute with ChildrenAsProperties set to `true`.
FIsNonParserAccessor	Gets a value that determines whether the control implements the IParserAccessor interface.
HasAspCode	Gets a value indicating whether the control contains any code blocks.
ID	Gets or sets the identifier property for the control to be built.
InDesigner	Returns whether the ControlBuilder is running in the designer.
InPageTheme	Gets a Boolean value indicating whether this ControlBuilder object is used to generate page themes.
ItemType	Gets the type set on the binding container.
Localize	Gets a Boolean value indicating whether the control that is created by this ControlBuilder object is localized.
NamingContainerType	Gets the type of the naming container for the control that this builder creates.
PageVirtualPath	Gets the virtual path of a page to be built by this ControlBuilder instance.
Parser	Gets the TemplateParser responsible for parsing the control.
ServiceProvider	Gets the service object for this ControlBuilder object.
SubBuilders	Gets a list of child ControlBuilder objects for this ControlBuilder object.
TagName	Gets the tag name for the control to be built.
TemplatePropertyEntries	Gets a collection of template property entries.
ThemeResolutionService	Gets an IThemeResolutionService object that is used in design time to manage control themes and skins.

Methods

AllowWhitespaceLiterals()	Determines whether white space literals are permitted in the content between a control's opening and closing tags. This method is called by the ASP.NET page framework.
AppendLiteralString(String)	Adds the specified literal content to a control. This method is called by the ASP.NET page framework.
AppendSubBuilder(ControlBuilder)	Adds builders to the ControlBuilder object for any child controls that belong to the container control.
BuildObject()	Builds a design-time instance of the control that is referred to by this ControlBuilder object.
CloseControl()	Called by the parser to inform the builder that the parsing of the control's opening and closing tags is complete.
CreateBuilderFromType(TemplateParser, ControlBuilder, Type, String, String, IDictionary, Int32, String)	Creates a ControlBuilder object from the specified tag name and object type, as well as other parameters defining the builder.
Equals(Object)	Determines whether the specified object is equal to the current object. (Inherited from Object)
GetChildControlType(String, IDictionary)	Obtains the Type of the control type corresponding to a child tag. This method is called by the ASP.NET page framework.
GetHashCode()	Serves as the default hash function. (Inherited from Object)
GetObjectPersistData()	Creates the ObjectPersistData object for this ControlBuilder object.
GetResourceKey()	Retrieves the resource key for this ControlBuilder object.
GetType()	Gets the Type of the current instance. (Inherited from Object)
HasBody()	Determines if a control has both an opening and closing tag. This method is called by the ASP.NET page framework.
HtmlDecodeLiterals()	Determines whether the literal string of an HTML control must be HTML decoded. This method is called by the ASP.NET page framework.
Init(TemplateParser, ControlBuilder, Type, String, String, IDictionary)	Initializes the ControlBuilder for use after it is instantiated. This method is called by the ASP.NET page framework.
MemberwiseClone()	Creates a shallow copy of the current Object. (Inherited from Object)
NeedsTagInnerText()	Determines if the control builder needs to get its inner text. If so, the SetTagInnerText(String) method must be called. This method is called by the ASP.NET page framework.
OnAppendToParentBuilder(ControlBuilder)	Notifies the ControlBuilder that it is being added to a parent control builder.
ProcessGeneratedCode(CodeCompileUnit, CodeTypeDeclaration, CodeTypeDeclaration, CodeMemberMethod, CodeMemberMethod)	Enables custom control builders to access the generated Code Document Object Model (CodeDom) and insert and modify code during the process of parsing and building controls.
SetResourceKey(String)	Sets the resource key for this ControlBuilder object.
SetServiceProvider(IServiceProvider)	Sets the service object for this ControlBuilder object.
SetTagInnerText(String)	Provides the ControlBuilder with the inner text of the control tag.
ToString()	Returns a string that represents the current object. (Inherited from Object)

Applies to

Product	Versions
.NET Framework	1.1, 2.0, 3.0, 3.5, 4.0, 4.5, 4.5.1, 4.5.2, 4.6, 4.6.1, 4.6.2, 4.7, 4.7.1, 4.7.2, 4.8, 4.8.1

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