CheckBoxDesigner Class
Extends design-time behavior for the CheckBox Web server control.
Assembly: System.Design (in System.Design.dll)
The CheckBoxDesigner class overrides the GetDesignTimeHtml method of the ControlDesigner class to ensure that the control is displayed with a meaningful representation at design time. If the Text property is empty, the GetDesignTimeHtml method of this class sets the Text property of the control to the Control::ID property of the control.
The following code example creates a custom designer class, named SampleCheckBoxDesigner, that inherits from the CheckBoxDesigner class. It overrides the GetDesignTimeHtml method. If the CheckBox::Text property has not been set previously, a call to this method sets it to a string and displays that string on the design surface. If the Text property has been set, the existing property value is displayed.
Imports System 'Imports System.Design Imports System.Drawing Imports System.ComponentModel Imports System.Web.UI.WebControls Imports System.Web.UI.Design Imports System.Web.UI.Design.WebControls 'Imports Examples.AspNet Namespace Examples.AspNet '.Design ' Create a class, named SampleCheckBoxDesigner, that overrides the ' GetDesignTimeHtml method to display the control on the design ' surface. Public Class SampleCheckBoxDesigner Inherits System.Web.UI.Design.WebControls.CheckBoxDesigner ' Override the GetDesignTimeHtml method to display a border on the ' control if the BorderStyle property has not been set by the user. Public Overrides Function GetDesignTimeHtml() As String Dim sampleCheckBox As SampleCheckBox = CType(Component, _ SampleCheckBox) Dim designTimeHtml As String = Nothing ' Check the control's BorderStyle property. If (sampleCheckBox.BorderStyle = BorderStyle.NotSet) Then ' Save the current value of the BorderStyle property. Dim oldBorderStyle As BorderStyle = _ sampleCheckBox.BorderStyle ' Change the value of the BorderStyle property and ' generate the design-time HTML. Try sampleCheckBox.BorderStyle = BorderStyle.Groove designTimeHtml = MyBase.GetDesignTimeHtml() ' If an exception occurs, call the GetErrorDesignTimeHtml ' method. Catch ex As Exception designTimeHtml = GetErrorDesignTimeHtml(ex) ' Restore the BorderStyle property to its original value. Finally sampleCheckBox.BorderStyle = oldBorderStyle End Try Else designTimeHtml = MyBase.GetDesignTimeHtml() End If Return designTimeHtml End Function End Class End Namespace
The following code example is a simple class, named SampleCheckBox, that inherits from the CheckBox class and is associated with the SampleCheckBoxDesigner class by the DesignerAttribute class.
Namespace Examples.AspNet ' The SampleCheckBox class that uses the SampleCheckBoxDesigner class. <Designer(GetType( _ Examples.AspNet.SampleCheckBoxDesigner))> _ Public Class SampleCheckBox Inherits CheckBox ' To customize the CheckBox class, insert code here. End Class End Namespace
- SecurityPermission
for calling unmanaged code. Demand value: Demand; Associated enumeration: UnmanagedCode.
System.ComponentModel.Design::ComponentDesigner
System.Web.UI.Design::HtmlControlDesigner
System.Web.UI.Design::ControlDesigner
System.Web.UI.Design.WebControls::CheckBoxDesigner
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.