LoginDesigner Class

Definition

public ref class LoginDesigner : System::Web::UI::Design::WebControls::CompositeControlDesigner

public class LoginDesigner : System.Web.UI.Design.WebControls.CompositeControlDesigner

type LoginDesigner = class
    inherit CompositeControlDesigner

Public Class LoginDesigner
Inherits CompositeControlDesigner

Inheritance

Object

ComponentDesigner

HtmlControlDesigner

ControlDesigner

CompositeControlDesigner

LoginDesigner

Examples

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

The example derives the MyLogin control from the Login. The MyLogin is a copy of the Login control. The example also derives the MyLoginDesigner class from the LoginDesigner and applies a DesignerAttribute attribute for the MyLoginDesigner on the MyLogin control.

The MyLoginDesigner overrides the PreFilterProperties method to make the NamingContainer property visible in the Properties grid at design time. It overrides the GetDesignTimeHtml method to draw a blue, dashed border around the control to make its extent more visible, if the BorderStyle property of the MyLogin control is the NotSet or None value. It overrides the GetErrorDesignTimeHtml method to generate the markup for a placeholder that includes the error message rendered in red, bold text.

using System;
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 MyLogin is a copy of the Login.
    [AspNetHostingPermission(SecurityAction.Demand, 
        Level = AspNetHostingPermissionLevel.Minimal)]
    [AspNetHostingPermission(SecurityAction.InheritanceDemand, 
        Level = AspNetHostingPermissionLevel.Minimal)]
    [Designer(typeof(Examples.CS.WebControls.Design.MyLoginDesigner))]
    public class MyLogin : Login
    {
    } // MyLogin

    // Override members of the LoginDesigner.
    [ReflectionPermission(SecurityAction.Demand, Flags=ReflectionPermissionFlag.MemberAccess)]
    public class MyLoginDesigner : LoginDesigner
    {
        // Generate the design-time markup for the control when an error occurs.
        protected override string GetErrorDesignTimeHtml(Exception e) 
        {
            // Write the error message text in red, bold.
            string errorRendering =
                "<span style=\"font-weight:bold; color:Red; \">" +
                e.Message + "</span>";

            return CreatePlaceHolderDesignTimeHtml(errorRendering);
        } // GetErrorDesignTimeHtml

        // Shadow the control properties with design-time properties.
        protected override void PreFilterProperties(IDictionary properties)
        {
            // Call the base method first.
            base.PreFilterProperties(properties);

            // Make the NamingContainer visible in the Properties grid.
            PropertyDescriptor selectProp = 
                (PropertyDescriptor)properties["NamingContainer"];
            properties["NamingContainer"] =
                TypeDescriptor.CreateProperty(selectProp.ComponentType, 
                    selectProp, BrowsableAttribute.Yes);
        } // PreFilterProperties

        // Generate the design-time markup.
        public override string GetDesignTimeHtml()
        {
            // Make the control more visible in the designer.  If the border 
            // style is None or NotSet, change the border to a blue dashed line. 
            MyLogin myLoginCtl = (MyLogin)ViewControl;
            string markup = null;

            // Check if the border style should be changed.
            if (myLoginCtl.BorderStyle == BorderStyle.NotSet ||
                myLoginCtl.BorderStyle == BorderStyle.None)
            {
                BorderStyle oldBorderStyle = myLoginCtl.BorderStyle;
                Color oldBorderColor = myLoginCtl.BorderColor;

                // Set the design time properties and catch any exceptions.
                try
                {
                    myLoginCtl.BorderStyle = BorderStyle.Dashed;
                    myLoginCtl.BorderColor = Color.Blue;

                    // Call the base method to generate the markup.
                    markup = base.GetDesignTimeHtml();
                }
                catch (Exception ex)
                {
                    markup = GetErrorDesignTimeHtml(ex);
                }
                finally
                {
                    // It is not necessary to restore the border properties 
                    // to their original values because the ViewControl 
                    // was used to reference the associated control and the 
                    // UsePreviewControl was not overridden.  

                    // myLoginCtl.BorderStyle = oldBorderStyle;
                    // myLoginCtl.BorderColor = oldBorderColor;
                }
            }
            else
            {
                // Call the base method to generate the markup.
                markup = base.GetDesignTimeHtml();
            }

            return markup;
        } // GetDesignTimeHtml
    } // MyLoginDesigner
} // Examples.CS.WebControls.Design

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 MyLogin is a copy of the Login.
    <AspNetHostingPermission(SecurityAction.Demand, _
        Level:=AspNetHostingPermissionLevel.Minimal)> _
    <AspNetHostingPermission(SecurityAction.InheritanceDemand, _
        Level:=AspNetHostingPermissionLevel.Minimal)> _
    <Designer(GetType(Examples.VB.WebControls.Design.MyLoginDesigner))> _
    Public Class MyLogin
        Inherits Login
    End Class

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

        ' Generate the design-time markup for the control when an error occurs.
        Protected Overrides Function GetErrorDesignTimeHtml( _
            ByVal ex As Exception) As String

            ' Write the error message text in red, bold.
            Dim errorRendering As String = _
                "<span style=""font-weight:bold; color:Red; "">" & _
                ex.Message & "</span>"

            Return CreatePlaceHolderDesignTimeHtml(errorRendering)

        End Function ' GetErrorDesignTimeHtml

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

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

            ' Make the NamingContainer visible in the Properties grid.
            Dim selectProp As PropertyDescriptor = _
                CType(properties("NamingContainer"), PropertyDescriptor)
            properties("NamingContainer") = _
                TypeDescriptor.CreateProperty(selectProp.ComponentType, _
                    selectProp, BrowsableAttribute.Yes)
        End Sub

        ' Generate the design-time markup.
        Public Overrides Function GetDesignTimeHtml() As String

            ' Make the control more visible in the designer.  If the border 
            ' style is None or NotSet, change the border to a blue dashed line. 
            Dim myLoginCtl As MyLogin = CType(ViewControl, MyLogin)
            Dim markup As String = Nothing

            ' Check if the border style should be changed.
            If (myLoginCtl.BorderStyle = BorderStyle.NotSet Or _
                myLoginCtl.BorderStyle = BorderStyle.None) Then

                Dim oldBorderStyle As BorderStyle = myLoginCtl.BorderStyle
                Dim oldBorderColor As Color = myLoginCtl.BorderColor

                ' Set the design time properties and catch any exceptions.
                Try
                    myLoginCtl.BorderStyle = BorderStyle.Dashed
                    myLoginCtl.BorderColor = Color.Blue

                    ' Call the base method to generate the markup.
                    markup = MyBase.GetDesignTimeHtml()

                Catch ex As Exception
                    markup = GetErrorDesignTimeHtml(ex)

                Finally
                    ' It is not necessary to restore the border properties 
                    ' to their original values because the ViewControl 
                    ' was used to reference the associated control and the 
                    ' UsePreviewControl was not overridden.  

                    ' myLoginCtl.BorderStyle = oldBorderStyle
                    ' myLoginCtl.BorderColor = oldBorderColor
                End Try

            Else
                ' Call the base method to generate the markup.
                markup = MyBase.GetDesignTimeHtml()
            End If

            Return markup

        End Function ' GetDesignTimeHtml
    End Class
End Namespace ' Examples.VB.WebControls.Design

Remarks

The Login control displays a user interface that allows a user to log on to the host Web site.

In a visual designer, when you switch from Source to Design view, the markup source code that describes the Login control is parsed and a design-time version of the control is created on the design surface. When you switch back to Source view, the design-time control is persisted to the markup source code and edited into the markup for the Web page. The LoginDesigner class provides design-time support for the Login control.

The LoginDesigner 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 AutoFormats property returns a collection of formatting schemes for display in the Auto Format dialog box.

• The TemplateGroups property returns a collection of template groups for the fields of the associated Login control and the top-level Login template.

• The UsePreviewControl property always returns true, indicating that the designer creates a temporary copy of the associated Login to generate the design-time markup.

The LoginDesigner class methods provide the following functionality:

• The GetDesignTimeHtml method returns the markup that is used to render the associated Login at design time.

• The GetEditableDesignerRegionContent method returns a serialized copy of the template for the associated Login.

• The GetErrorDesignTimeHtml method provides the markup that is used to render the associated Login at design time when an error has occurred.

• The Initialize method prepares the designer to view, edit, and design the associated Login.

• The PreFilterProperties method is used to remove properties from, add additional properties to, or shadow properties of the associated Login.

• The SetEditableDesignerRegionContent method sets a region of the associated Login from a serialized copy of a control template.

Constructors

Properties

Methods

Explicit Interface Implementations

Applies to

See also

• Login
• CompositeControl
• WebControl
• CompositeControlDesigner
• ControlDesigner
• HtmlControlDesigner
• ComponentDesigner
• Introduction to ASP.NET Control Designers
• Walkthrough: Creating a Basic Control Designer for a Web Server Control