TypeConverter.CreateInstance How does it works

[João Santa Bárbara]

Hi all
i have a class that i have made and i made an Typeconverter as well, and my
problem is
the code genereated in my form is

Dim ClassTest1 As TestApplication.ClassTest = New TestApplication.ClassTest
Me.MyClassTest = ClassTest1

Wich is quite good, but my problem is in my property browser i cannot change
any of my properties
' need the "DesignerSerializationVisibility " this in visible because this
is a form that must be inherited and i don´t want this property tobe writen
in the child form. unless it was changed in the child form .

i have declare my property like this

<LocalizableAttribute(True), _
Browsable(True), _
DesignerSerializationVisibility(DesignerSerializationVisibility.Visible), _
MergableProperty(False)> _
Public Property MyClassTest() As ClassTest
Get
Return xMyClassTest
End Get
Set(ByVal Value As ClassTest)
xMyClassTest = Value
xMyClassTest_ChangedProperty()
End Set
End Property
please see the code below

<System.ComponentModel.TypeConverter(GetType(ClassTypeConverter)), _
EditorBrowsable(EditorBrowsableState.Always), _
Serializable()> _
Public Class ClassTest
Inherits System.MarshalByRefObject
Implements System.IDisposable
Private xText As String = "Texto"
Private xColor As System.Drawing.Color = Color.Red
Public Event ChangedProperty()
Event testesss As EventHandler
Public Property Text() As String
Get
Return xText
End Get
Set(ByVal Value As String)
xText = Value
RaiseEvent ChangedProperty()
End Set
End Property
Public Property Color() As System.Drawing.Color
Get
Return xColor
End Get
Set(ByVal Value As System.Drawing.Color)
xColor = Value
RaiseEvent ChangedProperty()
End Set
End Property
<EditorBrowsable(EditorBrowsableState.Advanced)> _
Private Function ShouldSerializeColor() As Boolean
Return Not Me.Color.Equals(Color.Red)
End Function
<EditorBrowsable(EditorBrowsableState.Advanced)> _
Private Sub ResetColor()
Me.Color = Color.Red
End Sub
<EditorBrowsable(EditorBrowsableState.Advanced)> _
Private Function ShouldSerializeText() As Boolean
Return Me.Text <> "Texto"
End Function
<EditorBrowsable(EditorBrowsableState.Advanced)> _
Private Sub ResetText()
xText = "Texto"
End Sub

Public Sub Dispose() Implements System.IDisposable.Dispose
xColor = Nothing
End Sub
End Class


' Type Converter Class
Imports System.Reflection
Imports System.ComponentModel
Imports System
Imports System.Drawing
Imports System.Drawing.Design
Imports System.ComponentModel.Design.Serialization
Public Class ClassTypeConverter
Inherits ExpandableObjectConverter
Public Overloads Overrides Function CanConvertTo(ByVal context As
System.ComponentModel.ITypeDescriptorContext, ByVal destinationType As
System.Type) As Boolean
Try
If destinationType Is GetType(InstanceDescriptor) Then
Return True
End If
Return MyBase.CanConvertTo(context, destinationType)
Catch ex As Exception
MessageBox.Show("Erro CanConvertTo " & ex.StackTrace)
End Try
End Function
Public Overloads Overrides Function ConvertTo(ByVal context As
System.ComponentModel.ITypeDescriptorContext, ByVal culture As
System.Globalization.CultureInfo, ByVal value As Object, ByVal
destinationType As System.Type) As Object
Try
If destinationType Is Nothing Then
Throw New ArgumentNullException("Argumentos Invalidos")
End If
If destinationType Is GetType(InstanceDescriptor) Then
Dim ci As ConstructorInfo =
GetType(ClassTest).GetConstructor(Type.EmptyTypes)
Return New InstanceDescriptor(ci, Nothing, False)
End If
Return MyBase.ConvertTo(context, culture, value, destinationType)
Catch ex As Exception
MessageBox.Show("Erro ConvertTo" & ex.StackTrace)
End Try
End Function


Public Overloads Overrides Function CreateInstance(ByVal context As
System.ComponentModel.ITypeDescriptorContext, ByVal propertyValues As
System.Collections.IDictionary) As Object
Return New ClassTest 'Activator.CreateInstance(GetType(ClassTest))
End Function
Public Overloads Overrides Function GetCreateInstanceSupported(ByVal context
As System.ComponentModel.ITypeDescriptorContext) As Boolean
Return True
End Function

End Class

 

[João Santa Bárbara]

hi there ,,
just try to put aonther property in your MyProperty structure but not add it
to the constructor.
and then try to change the vaule at design time.
thsk
JSB

 

[joeycalisay]

and why would you not add it to the constructor of the struct? I believe
you have to because you will be instructing your TypeConverter which
constructor to use and if you will be using the old one (my two parameter
constructor), how will you serialize the value for the additional property?
Perhaps you can customize that with a custom CodeDom but it will be really
easier (and practical IMO) if your constructor (which the typeconverter will
use) properly initializes your struct instance...