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TriStateTreeview in VB.NET

, 19 Jan 2006
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A VB.NET implementation of a treeview with 3-state checkboxes using state image list

Introduction

The TreeView with checkboxes implemented in the .NET Framework (property TreeView.CheckBoxes = True) allows only 2 states (TreeNode.Checked = True or False). The implementation presented here:

  • Allows to use the state image list that is not directly available in the .NET Framework implementation.

  • Allows 3 states (4 including the state none) for a node: checked, unchecked, indeterminate.

  • Implements the logic to set the proper state of parents and children when the user changes the state of a node: it selects all children when the parent is selected, and set the state of the parent(s) to checked, unchecked or indeterminate depending on the number of children selected (all, none, etc.).

I have seen other TriState implementations in the C# section but they use the image list, not the state image list, for checkboxes and therefore doesn't allow to have icons and checkboxes for nodes at the same time.

Using the code

I have derived a TriStateTreeView class from the base TreeView class. This new class needs an additional state image list with icons for the 4 states: none, unchecked, checked, indeterminate (in this order).

The state image list is passed in the constructor:

  m_ctlTriStateTreeView = New TriStateTreeView(Me.StateImageList)

A new enum type is provided to specify the state of a node:

Friend Enum CheckBoxState
   None = 0
   Unchecked = 1
   Checked = 2
   Indeterminate = 3
End Enum

To add nodes to the treeview, you can use the AddTreeNode helper function of the TriStateTreeView class:


 objTreeNodeRoot = m_ctlTriStateTreeView.AddTreeNode( _
    m_ctlTriStateTreeView.Nodes, "My Computer", _
    IMG_COMPUTER, CheckBoxState.None)

To get the state of a node you use the GetTreeNodeState function of the TriStateTreeView class:


 Friend Function GetTreeNodeState(ByVal objTreeNode As _
    TreeNode) As CheckBoxState

To set the state of a node you use the SetTreeNodeState function of the TriStateTreeView class:


Friend Sub SetTreeNodeState(ByVal objTreeNode As _
    TreeNode, ByVal eCheckBoxState As CheckBoxState)

Points of Interest

The code intercepts the MouseUp and KeyUp events to change the state of a node (when clicking with the mouse or pressing space). Also, the code prevents expanding or collapsing a node double-clicking on the state image.

History

  • 27-April-2004: Initial version.

License

This article has no explicit license attached to it but may contain usage terms in the article text or the download files themselves. If in doubt please contact the author via the discussion board below.

A list of licenses authors might use can be found here

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Comments and Discussions

 
GeneralOnBeforeExpand & OnBeforeCollapse prevents expand collapse too much Pinmemberjsytniak2-Mar-09 10:55 
Generalcheckbox and afterchange event Pinmemberiwrschenk3-Dec-08 4:18 
AnswerRe: checkbox and afterchange event Pinmemberjsytniak26-Dec-08 11:23 
GeneralProblem with SetTreeNodeState method PinmemberOmar Vargas11-Nov-08 6:50 
NewsC# Version Pinmemberjsytniak7-May-08 4:37 
Generalnode tooltip Pinmemberkalany16-Apr-08 7:21 
GeneralRe: node tooltip - bug with state icons Pinmemberjsytniak7-May-08 4:40 
GeneralC# version with some minor enhancements Pinmemberalverdal20-Mar-08 7:16 
GeneralRe: C# version with some minor enhancements PinmemberMember 28343895-Oct-08 23:33 
QuestionCheck Boxes not showing up in my project Pinmembercrazytom25-Jan-08 11:03 
GeneralRe: Check Boxes not showing up in my project Pinmembercrazytom27-Jan-08 9:27 
GeneralRe: Check Boxes not showing up in my project Pinmemberkhendric5-Mar-08 4:32 
QuestionProblems with this class Pinmemberjonmach17-Nov-07 2:05 
AnswerRe: Problems with this class Pinmemberjonmach17-Nov-07 9:18 
AnswerRe: Problems with this class Pinmembermadmax824-Aug-10 4:02 
Generalpocket pc project Pinmemberrabosa21-Jun-07 0:58 
GeneralBeforeCheck Issue Pinmemberthierry_anthony13-Apr-07 8:30 
GeneralPopule windows root [modified] Pinmembermpdesign11-Feb-07 14:48 
QuestionTreeview state problem PinmemberAchintya Jha25-Oct-06 6:49 
AnswerRe: Treeview state problem Pinmemberpriman_p27-Sep-09 22:31 
GeneralLoadOnDemand does not work Pinmemberdevnet24719-Feb-06 0:35 
GeneralVery nice however... Pinmembervbinfo31-Jan-06 5:56 
GeneralRe: Very nice however... PinmemberCarlos J. Quintero31-Jan-06 6:17 
GeneralRe: Very nice however... Pinmemberdevnet24713-Feb-06 13:31 
GeneralRe: Very nice however... PinmemberNewton Burgos5-Aug-06 17:54 
I need this too please need help

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