CheckBox cascading selection

[David kroukamp]

Hi there

I am busy trying to make a treeview with tristate checkboxes and cascading selection of these checkboxes.

So I have read the topic before where you said to enable virtual mode which will call ValuePushed and ValueNeeded Methods... from there what do I do? My code is looking something like this:

    public void Initialize(DatabaseUserControl dbuc)
    {
        databaseUserControl = dbuc;
        tableColumnsDictionary = this.FillTableAndColumnsDictionary();
        var treeModel = tableColumnsDictionary.PopulateTreeView();
        this.treeViewAudits.Model = treeModel;
        nodeCheckBox1.VirtualMode = true;
        nodeCheckBox1.ValueNeeded += vNeeded;
        nodeCheckBox1.ValuePushed += vPushed;
        nodeCheckBox1.IsEditEnabledValueNeeded += IsEditEnabledValueNeeded;
        nodeCheckBox1.EditEnabled = true;
    }

     private static void IsEditEnabledValueNeeded(object sender, NodeControlValueEventArgs e)
    {
        if (e.Node.Children.Count != 0)//parents may be tristate
        {
            return;
        }

        //children may not be tristate (only parents i.e Nodes with other Nodes)
        e.Value = 0;
        var nodeCheckBox = (NodeCheckBox)sender;
        var checkedState = (CheckState)nodeCheckBox.GetValue(e.Node);
        nodeCheckBox.SetValue(e.Node, checkedState == CheckState.Checked ? CheckState.Unchecked : CheckState.Checked);

    }
    private void vPushed(object sender, NodeControlValueEventArgs e)
    {

        //var nodeCheckBox = (NodeCheckBox)sender;
       // var checkedState = (CheckState)nodeCheckBox.GetValue(e.Node);
       // checkedState=CheckState.Checked;//causes stackoverflow
        //e.Value = 1;
    }

    private void vNeeded(object sender, NodeControlValueEventArgs e)
    {

       // var nodeCheckBox = (NodeCheckBox)sender;
        //var checkedState = (CheckState)nodeCheckBox.GetValue(e.Node);
       // checkedState = CheckState.Unchecked;//causes stackoverflow
        // e.Value = 0;
    }

I do not know what to do in those methods.. I have a Custome Node class which looks like:

internal sealed class AuditObjectNode : Aga.Controls.Tree.Node
{

    private readonly string objName;

    public string ObjName
    {
        get
        {
            return this.objName;
        }
    }

    public CheckState Insert { get; set; }

    public CheckState Update { get; set; }

    public CheckState Delete { get; set; }

    public AuditObjectNode(string objName, CheckState insert, CheckState update, CheckState delete)
    {
        this.objName = objName;
        this.Insert = insert;
        this.Update = update;
        this.Delete = delete;
        this.Text = objName;
    }

}

Please can you advise on how to make checkbox cascading selection for tristate checkboxes. with children etc.

Also the minute I enable virtual mode I am unable to edit the checkboxes states via a click... And yes EditEnabled is set to true, but im guesing its those ValuePushed and ValueNeeded methods causing the problem

[David kroukamp]

Got a work around (without using VirtualMode). Simply set EditEnabled to true for all tristate NodeCheckBoxes (disable VirtualMode) than add method to be called for each NodeCheckBox :

    public void Initialize(DatabaseUserControl dbuc)
    {
        databaseUserControl = dbuc;
        tableColumnsDictionary = this.FillTableAndColumnsDictionary();
        var treeModel = tableColumnsDictionary.PopulateTreeView();
        this.treeViewAudits.Model = treeModel;

        nodeCheckBox1.IsEditEnabledValueNeeded += IsEditEnabledValueNeeded;
        nodeCheckBox2.IsEditEnabledValueNeeded += IsEditEnabledValueNeeded;
        nodeCheckBox3.IsEditEnabledValueNeeded += IsEditEnabledValueNeeded;
    }

The method would look something like this:

    private static void IsEditEnabledValueNeeded(object sender, NodeControlValueEventArgs e)
    {
        var nodeCheckBox = (NodeCheckBox)sender;
        var node = e.Node;
        var checkedState = (CheckState)nodeCheckBox.GetValue(node);
        var parentNode = node.Parent;

        if (node.Children.Count != 0) //parents may be tristate
        {
            foreach (var n in node.Children)
            {
                switch (checkedState)
                {
                    case CheckState.Unchecked:
                        nodeCheckBox.SetValue(n, CheckState.Checked);
                        break;
                    case CheckState.Checked:
                        nodeCheckBox.SetValue(n, CheckState.Unchecked);
                        break;
                    case CheckState.Indeterminate:
                        nodeCheckBox.SetValue(n, CheckState.Checked);
                        break;
                }
            }
        }

        //children may not be tristate (only parents i.e Nodes with other Nodes)
        e.Value = 0;
        var childNodeCheckState = checkedState == CheckState.Checked ? CheckState.Unchecked : CheckState.Checked;
        nodeCheckBox.SetValue(e.Node, childNodeCheckState);

        //there was not parent node so return
        if (parentNode == null)
        {
            return;
        }

        //a parent node exists check children and set parent tristate correctly
        var count = parentNode.Children.Count;
        var actualCount =
            parentNode.Children.Select(childNode => (CheckState)nodeCheckBox.GetValue(childNode)).
                       Count(childState => childState == CheckState.Checked);

        if (actualCount == 0)
            nodeCheckBox.SetValue(parentNode, CheckState.Unchecked);
        else if (count != actualCount)
            nodeCheckBox.SetValue(parentNode, CheckState.Indeterminate);
        else
            nodeCheckBox.SetValue(parentNode, CheckState.Checked);
    }