.NET Framework - How can i use the editor attribute?

Asked By Sa

22-Jun-07 04:36 AM

Hello there,

Please I need help on how to use the editor attribute. I am trying to learn
how to create User Controls? I created a UserControl using VB.NET. It
Contain a TreeView control and I want to expose the TreeView nodes
collection
and support the design-time environment by using the Editor attribute. But
when I tried to use it I get the following error message:
(value of type 'System.Windows.Forms.TreeNodeCollection' cannot be converted
to '1-dimensional array of System.Windows.Forms.TreeNodeCollection').

The editor attribute takes two parameters
(Typename as string, base typename as string)
(Typename as string, base typename as system.Type)
(Typename as system.type, base typename as system.Type)

I could not understand how to use these parameters?
I tried for many times during the last five days to resolve the problem but
I could not do it. Please someone help me and tell me how to write the
Editor attribute the correct way? What exactly the types that I should pass
to the editor attribute in my case?

The following is my tree node collection property:
Description("Gets the TreeView Nodes collection"), _
Category("TreeView"), _

DesignerSerializationVisibility(DesignerSerializationVisibility.Content), _
Editor(System.Windows.Forms.TreeNodeCollection,
System.Windows.Forms.TreeNodeCollection)> _
Public ReadOnly Property Nodes() As TreeNodeCollection()
Get
Return Me.tvTreeView.Nodes <------ (the error appears in this
line)
End Get
End Property

Thank you.

22-Jun-07 08:25 AM

A Design-Time Editor is a special Control that is used to set properties at
Design-Time. Desitn-Time Editors inherit System.Drawing.Design.UITypeEditor.
There is no built-in Editor for a TreeNodeCollection, so you have to create
one. Here's a good starting point for learning how:

http://msdn2.microsoft.com/en-us/library/ms171838.aspx

--
HTH,

Kevin Spencer
Microsoft MVP

Printing Components, Email Components,
FTP Client Classes, Enhanced Data Controls, much more.
DSI PrintManager, Miradyne Component Libraries:
http://www.miradyne.net

22-Jun-07 09:39 AM

Dear Kevin,
Thank you for your response. The link you provide me is a rely good starting
point and I’m going to read it carefully but in mean time please can you
answer this question for me.
Is the TreeNodeCollection type that requires a fully interactive UI (Modal
Dialog Editors)?
Thank you.

22-Jun-07 10:13 AM

Dear Kevin,

Why in C# i can pass TreeNodeCollection type to the Editor Attribute but in
VB I get the following error:
(value of type 'System.Windows.Forms.TreeNodeCollection' cannot be converted
to '1-dimensional array of System.Windows.Forms.TreeNodeCollection').

Is the implementation of Editor attribute in c# different then VB.?

C# Codes:
[Browsable(true), _Description("Gets the TreeView Nodes collection"),
Category("TreeView"),
DesignerSerializationVisibility(DesignerSerializationVisibility.Content),
Editor(typeof(TreeNodeCollection), typeof(TreeNodeCollection))]
public TreeNodeCollection Nodes
{
get
{
return this.tvTreeView.Nodes;
}
}

VB Codes:
Description("Gets the TreeView Nodes collection"), _
Category("TreeView"), _

DesignerSerializationVisibility(DesignerSerializationVisibility.Content), _
EditorAttribute(GetType(TreeNodeCollection), _
GetType(TreeNodeCollection))> _
Public ReadOnly Property Nodes() As TreeNodeCollection()
Get
Return Me.tvTreeView.Nodes
End Get
End Property

Thank you.

22-Jun-07 11:14 AM

If you want to add elements to a TreeNodeCollection, you will need to
implement a Modal Dialog Editor, yes, if that's what you're asking.

--
HTH,

Kevin Spencer
Microsoft MVP

Printing Components, Email Components,
FTP Client Classes, Enhanced Data Controls, much more.
DSI PrintManager, Miradyne Component Libraries:
http://www.miradyne.net

22-Jun-07 11:18 AM

Hi Sam,

A TreeNodeCollection is not a UITypeEditor class. A TreeNodeCollection is
just a Collection of TreeNode instances. I thought you were clear on that
issue. You need to implement and reference a UITypeEditor class, and
reference that in the Editor attribute. As to why you got the specific
exception message, I have no idea. The code you wrote was bound to throw an
exception, but as to where exactly in the Framework processing chain
something barfed and why iot barfed at that specific point, or what it was
trying to do at that point, I can't say.

--
HTH,

Kevin Spencer
Microsoft MVP

Printing Components, Email Components,
FTP Client Classes, Enhanced Data Controls, much more.
DSI PrintManager, Miradyne Component Libraries:
http://www.miradyne.net

22-Jun-07 11:59 AM

Hello Kevin,

If I need to implement and reference a UITypeEditor class; and reference
that in the Editor attribute; then could you please tell me; Why the
implementation of the Editor attribute work fine with a TreeNodeCollection
and without using the (UITypeEditor)  in C#. I have the sample and it’s
working with no problems at all which make me confused and wandering!

Can I post the sample code written in c#; so you can see it and tell me why?

Thank you.