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Posted 9 May 2005
Licenced CPOL

Rich Design Time Featured TreeList Control

, 9 May 2005
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A Tree like component with rich design time features.

Sample Image


There are actually several reasons that made me start doing this:

  • There are almost no tree control samples available out there. Nothing for VB.NET.
  • There are almost no examples of rich time design support for collection of controls.
  • I needed a tree with various image sizes (for a DVD collection).
  • I hated to not be able to show PNG images correctly within a tree.
  • I wanted to go deep into a control.

I'm not saying my article or my component is great work, but at least it'll give the newbie a rough start on that matter. Of course, I would say that my work is not free! I'd like to put it as ShareYourWorkWare ;) Meaning that if someone wants to improve it, he could make the others benefit as well.


This article will reflect several bits of code that were put together in a kind of complete component. Among those you'll find:

  • How to build a tree (a component that has a collection property that itself has collections, etc.)
    • Implementing a real CollectionBase property.
  • How to make a control "Design Time Enabled"
    • Using <Designer()>.
    • Inheriting from ControlDesigner.
  • Twisting the PropertyGrid.
    • Collections
    • TypeConverters
    • PropertyDescriptor
    • Implementing ICustomTypeDescriptor
  • And many more.


Mea culpa, I know... I've been reusing two nice piece of code that are available on the web. First of all, the great "Managed C++ Wrapper of UxTheme" from Don Kackman, and secondly, The "VisualStyles" provider from SkyBound.

The code itself

Let's try to start from somewhere.

As stated before, I wanted to write a tree control. Which is not an easy thing to do, especially if you have no clue on how to start. First, I'd thought about deriving from the original TreeView control, but I soon realized that it was not possible for what I wanted.

In fact, I needed a tree control that is able to show images that are not always of the same size. Point was: creating a DVD collection application that shows all DVDs within a tree, showing a thumbnail image of the DVD cover. I also imagined a control that could have the famous Text property as long as an "optional" description.


This is the main component. It's derived from Control. I've read somewhere on the web that the tree is supposed to take care of all the paintings. That's how I've implemented it. The main properties of TreeList are:

  • Nodes (represents a collection of TreeListNode)
  • SelectedNode (the node currently selected)
  • PointedNode (the node currently pointed by the right mouse click).

I specified a Designer (shown below) in order to enable rich design time experience. This is how it is declared:

<Designer(GetType(TreeListDesigner))> _
Public Class TreeList Inherits Control

The Nodes property needed to have some special definition as well to see it correctly in the PropertyGrid:

Private WithEvents _Nodes As TreeListNodeCollection
    <Category("Collection"), _
    DesignerSerializationVisibility(DesignerSerializationVisibility.Content)> _
    Public ReadOnly Property Nodes() As TreeListNodeCollection
            Return _Nodes
        End Get
    End Property

It's gotta be using the DesignerSerializationVisibility.Content in order to be able to display it that way:

Sample Image

Notice that instead of having the traditional "(Collection)", I show the number of subnodes along with a nice (+) sign to expand it and show its internal properties.


This holds a collection of TreeListNodes (it's represented as the "Nodes" property). That's its definition:

<TypeConverter(GetType(TreeListNodeCollectionConverter)), _
Editor(GetType(TreeListNodeCollectionEditor), GetType(UITypeEditor)), _
DesignTimeVisible(False), _
ToolboxItem(False), _
Serializable()> _
Public Class TreeListNodeCollection
    Inherits CollectionBase
    Implements ICustomTypeDescriptor

Notice here, the use of a TypeConverter. (That allows to show "3 node(s)" instead of "(Collection)", the user of a customized Editor avoids the problem when you have a collection of collection within a property.)


This represents a node. It's inherited from Component. That was the only way to achieve a correct designer for the TreeList. It is defined that way:

<TypeConverter(GetType(TreeListNodeConverter)), _
DesignTimeVisible(False), _
ToolboxItem(False), _
Serializable()> _
Public Class TreeListNode
    Inherits Component

It also has a property called "Nodes" which represents a TreeListNodeCollection (in order to hold its child nodes).


This is the designer of the TreeList component, it inherits from ControlDesigner and allows the user to select a node at design time. It also helps when a node is selected to change the content of the PropertyGrid displayed at design time.

TreeListNodeCollectionConverter & TreeListNodeConverter

Those are the converters for Collection and Node, it allows to change their respective visualizations on the PropertyGrid object. For instance, a node showing its name instead of "TreeListNode1".


This is the collection editor stated above. Allows to use a CollectionEditor from within another CollectionEditor.


This is the piece that makes Nodes have its little (+) sign at design time ;)

Points of Interest

I've learned a lot of things writing this component. I know that it is not really finished yet, but I hope that other people will join in to move forward and bring it to a stable state.


Sample Image

I also wanted to implement a possibility to show a tree being filled without having to wait for a non responsive control. Therefore the property "IsBusy()" of the TreeList can be set to show a progressbar.


Sample Image

I've also put the option to draw the tree (kind of fantasy) without the Windows XP styles.


Sample Image

I wanted to have scrollbars if the content of the control was too small to show everything. This was a bit of a question for me. I used the Skybound.VisualStylesProvider to achieve the XP look.

Additional insight

I'll be writing more in-depth about this control later on if I see that people like it.


That was my first article guys, hope you enjoyed it ;)

  • May 06, 2005 - v.0.1.


This article, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)


About the Author

Nicolas Wälti
Software Developer (Senior)
Switzerland Switzerland
No Biography provided

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Comments and Discussions

GeneralMy vote of 3 Pin
SunKwon4-May-12 15:01
memberSunKwon4-May-12 15:01 
Questionhow I get this application in vc++ Pin
jatin dave8-Jan-09 3:29
memberjatin dave8-Jan-09 3:29 
GeneralNo more supported Pin
Nicolas Wälti25-Aug-07 23:20
memberNicolas Wälti25-Aug-07 23:20 
Questionneed for vb 2005 Pin
genesi3605-Aug-07 19:43
membergenesi3605-Aug-07 19:43 
GeneralPropertyGrid Question Pin
@FrankDrebin@31-Jul-07 1:34
member@FrankDrebin@31-Jul-07 1:34 
GeneralRe: PropertyGrid Question Pin
Nicolas Wälti31-Jul-07 1:55
memberNicolas Wälti31-Jul-07 1:55 
QuestionAnybody has this working on VS 2005? Pin
Vicmart6913-Mar-07 14:48
memberVicmart6913-Mar-07 14:48 
Generaldepth Pin
nextmove20-Sep-06 10:34
membernextmove20-Sep-06 10:34 
AnswerRe: depth Pin
Nicolas Wälti20-Sep-06 19:41
memberNicolas Wälti20-Sep-06 19:41 
GeneralRe: depth Pin
nextmove21-Sep-06 6:21
membernextmove21-Sep-06 6:21 
Generalparent Property Pin
mcs@gdiniter.it18-Sep-06 3:01
membermcs@gdiniter.it18-Sep-06 3:01 
GeneralProblem of "first node can be selected " and my Trying to fix Pin
BNW8-Jul-06 23:18
memberBNW8-Jul-06 23:18 
QuestionHow can I build the tree from the database using parent and child table Pin
xhaileyn30-Dec-05 1:13
memberxhaileyn30-Dec-05 1:13 
GeneralDynamically added nodes fix Pin
Kuling22-Oct-05 2:11
memberKuling22-Oct-05 2:11 
GeneralTransparency Pin
Chris Kolkman21-Oct-05 6:06
memberChris Kolkman21-Oct-05 6:06 
GeneralRe: Transparency Pin
Nicolas Wälti10-Mar-06 3:11
memberNicolas Wälti10-Mar-06 3:11 
GeneralRe: Transparency Pin
Chris Kolkman10-Mar-06 3:56
memberChris Kolkman10-Mar-06 3:56 
Generaljust some advice Pin
Huma d Allan30-Aug-05 23:24
memberHuma d Allan30-Aug-05 23:24 
GeneralRe: just some advice Pin
Nicolas Wälti1-Sep-05 19:22
memberNicolas Wälti1-Sep-05 19:22 
QuestionHow to use ProgressBar in TreeList Pin
DotNET7422-Aug-05 22:11
memberDotNET7422-Aug-05 22:11 

I want to know if you can give me an example for use the progress mode in your TreeList.

AnswerRe: How to use ProgressBar in TreeList Pin
Nicolas Wälti23-Aug-05 2:00
memberNicolas Wälti23-Aug-05 2:00 
GeneralMouseDown problem Pin
DotNET747-Jul-05 23:46
memberDotNET747-Jul-05 23:46 
GeneralRe: MouseDown problem Pin
Nicolas Wälti7-Jul-05 23:55
memberNicolas Wälti7-Jul-05 23:55 
GeneralDynamically added nodes and scrollbars Pin
Allixria27-Jun-05 13:51
memberAllixria27-Jun-05 13:51 
GeneralRe: Dynamically added nodes and scrollbars Pin
Allixria27-Jun-05 18:01
memberAllixria27-Jun-05 18:01 

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