ControlBuilder Klas

Definitie

public ref class ControlBuilder

public class ControlBuilder

type ControlBuilder = class

Public Class ControlBuilder

Overname

Object

ControlBuilder

Afgeleid

System.Web.UI.CodeStatementBuilder

System.Web.UI.DataSourceControlBuilder

System.Web.UI.HtmlControls.HtmlEmptyTagControlBuilder

System.Web.UI.HtmlControls.HtmlHeadBuilder

System.Web.UI.HtmlControls.HtmlSelectBuilder

Meer…

Voorbeelden

In het volgende codevoorbeeld wordt een Table besturingselement gemaakt waarvan de kenmerken en inhoud worden gedefinieerd op het moment dat de tabel wordt gebouwd. Hier volgt de opdrachtregel die moet worden gebruikt om het uitvoerbare bestand te bouwen.

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

In het volgende codevoorbeeld wordt het vorige aangepaste besturingselement gebruikt. Met name wordt er een tabel gebouwd waarvan de kenmerken en inhoud tijdens runtime worden gedefinieerd. U ziet dat de waarden in de @Register-instructie de vorige opdrachtregel weerspiegelen.

<%@ 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>

Opmerkingen

Standaard is elk besturingselement op een pagina gekoppeld aan een standaardklasse ControlBuilder . Tijdens het parseren bouwt het ASP.NET paginaframework een structuur van ControlBuilder-objecten die overeenkomen met de structuur van besturingselementen voor de pagina. De ControlBuilder structuur wordt vervolgens gebruikt om paginacode te genereren om de besturingsstructuur te maken. Naast onderliggende besturingselementen definieert het ControlBuilder gedrag van hoe de inhoud in besturingstags wordt geparseerd. U kunt dit standaardgedrag overschrijven door uw eigen aangepaste opbouwfunctieklasse voor besturingselementen te definiëren. Dit wordt gedaan door als volgt een ControlBuilderAttribute kenmerk toe te passen op de klasse van de opbouwfunctie voor besturingselementen:

[ControlBuilderAttribute(typeof(ControlBuilderType))]

Zie ook

• Control
• WebControl
• Page
• ControlBuilderAttribute
• ParseChildrenAttribute
• PersistChildrenAttribute
• AddParsedSubObject(Object)