HierarchicalDataBoundControlDesigner Class

Definition

public ref class HierarchicalDataBoundControlDesigner : System::Web::UI::Design::WebControls::BaseDataBoundControlDesigner

public class HierarchicalDataBoundControlDesigner : System.Web.UI.Design.WebControls.BaseDataBoundControlDesigner

type HierarchicalDataBoundControlDesigner = class
    inherit BaseDataBoundControlDesigner

Public Class HierarchicalDataBoundControlDesigner
Inherits BaseDataBoundControlDesigner

Inheritance

Object

ComponentDesigner

HtmlControlDesigner

ControlDesigner

BaseDataBoundControlDesigner

HierarchicalDataBoundControlDesigner

Derived

System.Web.UI.Design.WebControls.MenuDesigner

System.Web.UI.Design.WebControls.TreeViewDesigner

Examples

The following code example shows how to extend the HierarchicalDataBoundControlDesigner class to change the appearance of controls that are derived from the HierarchicalDataBoundControl control at design time.

The example derives the MyHierarchicalDataBoundControl class from the HierarchicalDataBoundControl. The MyHierarchicalDataBoundControl class is simply a copy of the HierarchicalDataBoundControl. The example also derives the MyHierarchicalDataBoundControlDesigner class from the HierarchicalDataBoundControlDesigner class and places a DesignerAttribute object for the MyHierarchicalDataBoundControlDesigner on the MyHierarchicalDataBoundControl class.

The MyHierarchicalDataBoundControlDesigner overrides the PreFilterProperties method to make the NamingContainer property visible in the Properties grid at design time. It overrides the GetDesignTimeHtml method to generate the markup for a placeholder if the design time markup is null or Empty, or if the design-time markup is an empty <span> block (that is, if there is no inner markup between the <span …> and </span> tags).

using System;
using System.IO;
using System.Web;
using System.Drawing;
using System.Web.UI.WebControls;
using System.Web.UI.Design.WebControls;
using System.Collections;
using System.ComponentModel;
using System.Security.Permissions;

namespace Examples.CS.WebControls.Design
{
    // The MyHierarchicalDataBoundControl is a copy of the 
    // HierarchicalDataBoundControl.
    [AspNetHostingPermission(SecurityAction.Demand, 
        Level = AspNetHostingPermissionLevel.Minimal)]
    [AspNetHostingPermission(SecurityAction.InheritanceDemand, 
        Level = AspNetHostingPermissionLevel.Minimal)]
    [Designer(typeof(Examples.CS.WebControls.Design.
        MyHierarchicalDataBoundControlDesigner))]
    public class MyHierarchicalDataBoundControl : 
        HierarchicalDataBoundControl
    {
    } // MyHierarchicalDataBoundControl

    // Override members of the ierarchicalDataBoundControlDesigner.
    [ReflectionPermission(SecurityAction.Demand, Flags=ReflectionPermissionFlag.MemberAccess)]
    public class MyHierarchicalDataBoundControlDesigner : 
        HierarchicalDataBoundControlDesigner
    {
        const string bracketClose = ">";
        const string spanOpen = "<SPAN";
        const string spanClose = "</SPAN>";

        // Return the markup for a placeholder, if the inner markup is empty.
        // For brevity, the code that is used to detect embedded white_space 
        // in the tags is not shown.
        public override string GetDesignTimeHtml()
        {
            // Get the design-time markup from the base method.
            string markup = base.GetDesignTimeHtml();

            // If the markup is null or empty, return the markup 
            // for the placeholder.
            if(string.IsNullOrEmpty(markup))
                return GetEmptyDesignTimeHtml();

            // Make the markup uniform case so that the IndexOf will work.
            string MARKUP = markup.ToUpper();
            int charX;

            // Look for a <span ...> tag.
            if ((charX = MARKUP.IndexOf(spanOpen)) >= 0)
            {
                // Find closing bracket of span open tag.
                if ((charX = MARKUP.IndexOf(bracketClose, 
                        charX+spanOpen.Length)) >= 0)
                {
                    // If the inner markup of <span ...></span> is empty, 
                    // return the markup for a placeholder.
                    if (string.Compare(MARKUP, charX + 1, spanClose, 0, 
                                        spanClose.Length) == 0)

                        return GetEmptyDesignTimeHtml();
                }
            }
            // Return the original markup, if the inner markup is not empty.
            return markup;
        }

        // Shadow the control properties with design-time properties.
        protected override void PreFilterProperties(IDictionary properties)
        {
            string namingContainer = "NamingContainer";

            // Call the base method first.
            base.PreFilterProperties(properties);

            // Make the NamingContainery visible in the Properties grid.
            PropertyDescriptor selectProp =
                (PropertyDescriptor)properties[namingContainer];
            properties[namingContainer] =
                TypeDescriptor.CreateProperty(selectProp.ComponentType,
                    selectProp, BrowsableAttribute.Yes);
        } // PreFilterProperties
    } // MyHierarchicalDataBoundControlDesigner
} // Examples.CS.WebControls.Design

Imports System.IO
Imports System.Web
Imports System.Drawing
Imports System.Web.UI.WebControls
Imports System.Web.UI.Design.WebControls
Imports System.Collections
Imports System.ComponentModel
Imports System.Security.Permissions

Namespace Examples.VB.WebControls.Design

    ' The MyHierarchicalDataBoundControl is a copy of the 
    ' HierarchicalDataBoundControl.
    <AspNetHostingPermission(SecurityAction.Demand, _
        Level:=AspNetHostingPermissionLevel.Minimal)> _
    <AspNetHostingPermission(SecurityAction.InheritanceDemand, _
        Level:=AspNetHostingPermissionLevel.Minimal)> _
    <Designer(GetType(Examples.VB.WebControls.Design. _
        MyHierarchicalDataBoundControlDesigner))> _
    Public Class MyHierarchicalDataBoundControl
        Inherits HierarchicalDataBoundControl
    End Class

    ' Override members of the HierarchicalDataBoundControlDesigner.
    <ReflectionPermission(SecurityAction.Demand, Flags:=ReflectionPermissionFlag.MemberAccess)> _
    Public Class MyHierarchicalDataBoundControlDesigner
        Inherits HierarchicalDataBoundControlDesigner

        Private Const bracketClose As String = ">"
        Private Const spanOpen As String = "<SPAN"
        Private Const spanClose As String = "</SPAN>"

        ' Return the markup for a placeholder, if the inner markup is empty.
        ' For brevity, the code that is used to detect embedded white_space 
        ' in the tags is not shown.
        Public Overrides Function GetDesignTimeHtml() As String

            ' Get the design-time markup from the base method.
            Dim markup As String = MyBase.GetDesignTimeHtml()

            ' If the markup is null or empty, return the markup 
            ' for the placeholder.
            If String.IsNullOrEmpty(markup) Then
                Return GetEmptyDesignTimeHtml()
            End If

            ' Make the markup uniform case so that the IndexOf will work.
            Dim markupUC As String = markup.ToUpper()
            Dim charX As Integer

            ' Look for a <span ...> tag.
            charX = markupUC.IndexOf(spanOpen)
            If charX >= 0 Then

                ' Find closing bracket of span open tag.
                charX = markupUC.IndexOf(bracketClose, charX + spanOpen.Length)
                If charX >= 0 Then

                    ' If the inner markup of <span ...></span> is empty, 
                    ' return the markup for a placeholder.
                    If String.Compare(markupUC, charX + 1, _
                        spanClose, 0, spanClose.Length) = 0 Then

                        Return GetEmptyDesignTimeHtml()
                    End If
                End If
            End If

            ' Return the original markup, if the inner markup is not empty.
            Return markup
        End Function ' GetDesignTimeHtml

        ' Shadow the control properties with design-time properties.
        Protected Overrides Sub PreFilterProperties( _
            ByVal properties As IDictionary)

            Dim namingContainer As String = "NamingContainer"

            ' Call the base method first.
            MyBase.PreFilterProperties(properties)

            ' Make the NamingContainery visible in the Properties grid.
            Dim selectProp As PropertyDescriptor = _
                CType(properties(namingContainer), PropertyDescriptor)
            properties(namingContainer) = _
                TypeDescriptor.CreateProperty(selectProp.ComponentType, _
                    selectProp, BrowsableAttribute.Yes)
        End Sub
    End Class
End Namespace ' Examples.VB.WebControls.Design

Remarks

In a designer host, when the user switches from Source to Design view, the markup source code that describes a control that is derived from the HierarchicalDataBoundControl abstract class is parsed and a design-time version of the control is created on the design surface. When the user switches back to Source view, the design-time control is persisted to markup source code and edited into the markup for the Web page. The HierarchicalDataBoundControlDesigner class provides design-time support for controls that are derived from the HierarchicalDataBoundControl in a designer host.

The HierarchicalDataBoundControlDesigner class properties provide the following functionality:

• The ActionLists property returns a DesignerActionListCollection object, which typically contains an object that is derived from the DesignerActionList class for each level in the inheritance tree of the designer.

• The DataSourceDesigner property provides access to the designer of the data source, if one is defined.

• The DesignerView property gets the default view of the data source that is bound to the associated control.

• The UseDataSourcePickerActionList property determines whether the control should render its default action lists for choosing and creating data sources.

The HierarchicalDataBoundControlDesigner class methods provide the following functionality:

• The ConnectToDataSource method performs the actions that are necessary to connect to the current data source.

• The CreateDataSource method creates a new data source for the associated control.

• The DataBind method binds the associated control that is derived from the HierarchicalDataBoundControl class to a design-time data source.

• The DisconnectFromDataSource method performs the actions that are necessary to disconnect from the current data source.

• The GetDesignTimeDataSource method gets a data source that can be used at design time for the associated control.

• The GetSampleDataSource method constructs a sample data source that can be used at design time for the associated control.

• The PreFilterProperties method is used to remove properties from or add additional properties to or to shadow properties of the associated control that is derived from the HierarchicalDataBoundControl class.

Constructors

Properties

Methods

Explicit Interface Implementations

Applies to

See also

• HierarchicalDataBoundControl
• DataBoundControlDesigner
• Introduction to ASP.NET Control Designers
• Walkthrough: Creating a Basic Control Designer for a Web Server Control