asked on

Web Custom Control - Multi-level Properties

I am creating a Web Custom Control based on a calendar dll I wrote.

The DLL has a class called CellProperties which had properties such as backcolor, forecolor, etc. Then when I instantialed the dll I would set properties such as:

objCalendar.Heading.BackColor = Color.AliceBlue
objCalendar.Heading,ForeColor = Color.Black
etc...

Now, in creating this as a Web Custom Control, I want the properties to appear similar to the way Font shows up in the Propoerties screen. That is, a title of Font with a "plus" box. Then clicking on the "plus" will drop down the sub properties.

How do I do this?

I tried the following, but it doesn't work:

<Bindable(True), Category("Appearence"), DefaultValue("")> Property [Heading]() As myCalendar.CellProperties
Get
Return m_propHeading
End Get
Set(ByVal Value As BCP.Web.Calendar.CellProperties)
m_propHeading = Value
End Set
End Property

nauman_ahmed

Have a look on the following article:

http://www.theserverside.net/developmentor/downloads/whitepapers/designint.pdf

HTH, nauman

Clif

ASKER

Being the lazy person I am...

Is there any example in Visual Basic?

Justin_W

First, you need to make your custom property Public. E.g.:

<Bindable(True), Category("Appearence"), DefaultValue("")> Public Property [Heading]() As myCalendar.CellProperties

All of the properties in myCalendar.CellProperties that you want to expose should also be Public.

nauman_ahmed

Actually, the .Net way is very easy either if you code in C# or VB. You just need to have concepts of Object Oriented programming, and since VB.net is an object oriented language, you will need to learn that too :) Its not that diffcult and I think you will be able to learn it quickly. While learning just glance on the way objects or statement defined in both the language.

Also have a look at the following URL cuz I think it has some good stuf:

http://www.microsoft.com/downloads/details.aspx?familyid=3ff9c915-30e5-430e-95b3-621dccd25150&displaylang=en

HTH, nauman

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nauman_ahmed

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Clif

ASKER

The tutorial is also in C#.

I can code pretty darn well in VB. I can also read a good bit of C (and C++ and C#). But there are a few things I don't get.

For example, in the tutorial you posted:

[TypeConverter(typeof(PersonConverter))]
public class Person {
private string firstName = "";
private string lastName = "";
private int age = 0;

public int Age {
get {
return age;
}
set {
age = value;
}
}

public string FirstName {
get {
return firstName;
}
set {
this.firstName = value;
}
}

public string LastName {
get {
return lastName;
}
set {
this.lastName = value;
}
}
}

I can convert all of the above into VB except for the first line.

What the heck does this mean?
[TypeConverter(typeof(PersonConverter))]

Also, again from the tutorial:
internal class PersonConverter : ExpandableObjectConverter {

public override bool CanConvertFrom(
ITypeDescriptorContext context, Type t) {

if (t == typeof(string)) {
return true;
}
return base.CanConvertFrom(context, t);
}
.
.
.
}

Is this the same as (in VB)
Private Class PersonConverter
Inherits ExpandableObjectConverter
Public Overrides Function CanConvertFrom(context As ITypeDescriptorContext, t As Type)
If TypeOf(t) Is String Then
Return True
End If
'In the next line, what is the VB equivelant of 'base'?
Return base.CanConvertFrom(context, t)
End Function
.
.
.
End Class

Justin_W

> What the heck does this mean?
[TypeConverter(typeof(PersonConverter))]

It is the C# version of Attributes:
<TypeConverterAttribute(typeof(PersonConverter))> Public Class Person

nauman_ahmed

Private Class PersonConverter
Inherits ExpandableObjectConverter
Friend Overrides Function CanConvertFrom(context As ITypeDescriptorContext, t As Type)
If TypeOf(t) Is String Then
Return True
End If
'In the next line, what is the VB equivelant of 'base'?
Return base.CanConvertFrom(context, t)
End Function
.
.
.
End Class

Justin_W

base -> mybase

Clif

ASKER

Ok, using the code from the link provided by nauman_ahmed at:
http://msdn.microsoft.com/library/default.asp?url=/library/en-us/dndotnet/html/vsnetpropbrow.asp
I rewrote it from C# to VB.net.

It isn't working. Where did I go wrong?

'Step 1:
'Tried:
' <TypeConverterAttribute(typeof(PersonConverter))> Public Class Person
' as JustinW suggested, error "Is Expected")
<TypeConverter("PersonConverter")> Public Class Person
Private m_sFirstName As String = ""
Private m_sLastName As String = ""
Private m_nAge As Integer = 0

Public Property Age() As Integer
Get
Return m_nAge
End Get
Set(ByVal Value As Integer)
m_nAge = Value
End Set
End Property

Public Property FirstName() As String
Get
Return m_sFirstName
End Get
Set(ByVal Value As String)
m_sFirstName = Value
End Set
End Property

Public Property LastName() As String
Get
Return m_sLastName
End Get
Set(ByVal Value As String)
m_sLastName = Value
End Set
End Property

'Step 2:
Private Class PersonConverter
Inherits ExpandableObjectConverter

Public Overloads Function CanConvertFrom(ByVal context As ITypeDescriptorContext, _
ByVal t As Type) As Boolean

If TypeOf (t) Is String Then
Return True
End If
Return MyBase.CanConvertFrom(context, t)
End Function

'Changed from Overrides to Overloads because VB.net didn't like the former
Public Overloads Function ConvertFrom(ByVal context As ITypeDescriptorContext, _
ByVal info As System.Globalization.CultureInfo, _
ByVal value As Object) As Object

Try
If TypeOf (value) Is String Then
Dim s As String = CType(value, String)
' parse the format "Last, First (Age)"
'
Dim comma As Integer = s.IndexOf(",")
If comma <> -1 Then
' now that we have the comma, get
' the last name.
Dim last As String = s.Substring(0, comma)
Dim paren As Integer = s.LastIndexOf("(")
If paren <> -1 And _
s.LastIndexOf(")") = s.Length - 1 Then
' pick up the first name
Dim first As String = _
s.Substring(comma + 1, paren - comma - 1)
' get the age
Dim age As Integer = Int32.Parse(s.Substring(paren + 1, s.Length - paren - 2))
Dim p As Person = New Person
p.Age = age
p.LastName = last.Trim()
p.FirstName = first.Trim()
Return p
End If
End If
End If
Catch
' if we got this far, complain that we
' couldn't parse the string
'
Throw New ArgumentException("Can not convert '" + CType(value, String) + "' to type Person")

End Try
Return MyBase.ConvertFrom(context, info, value)
End Function

'Changed from Overrides to Overloads because VB.net didn't like the former
Public Overloads Function ConvertTo(ByVal context As ITypeDescriptorContext, _
ByVal culture As System.Globalization.CultureInfo, _
ByVal value As Object, _
ByVal destType As Type) As Object
If TypeOf (destType) Is String And TypeOf (value) Is Person Then
Dim p As Person = CType(value, Person)
' simply build the string as "Last, First (Age)"
Return p.LastName & ", " & p.FirstName & " (" & p.Age.ToString() & ")"
End If
Return MyBase.ConvertTo(context, culture, value, destType)
End Function
End Class
End Class

'Step 3 (Goes in Web Custom Control class):
Private p As Person = New Person
Public Property [Person]() As Person
Get
Return p
End Get
Set(ByVal Value As Person)
p = Value
End Set
End Property

Clif

ASKER

Ok, I found a great C# to VB Translator here:
http://authors.aspalliance.com/aldotnet/examples/translate.aspx

The code produced from the demo provided works (almost). The properties show up on the properties list as I wanted.

Actually I wasn't too far off in the translation I did. :)

At any rate, as I said it *almost* works. Everything is fine except the Web Custom Control doesn't respond to the properties.

Be on the look out for another question from me on this matter. :)

Thanks.