How to deactiveating Treeview's CheckBox

Question

I have a two treeview with some nodes which there are check-boxes behind them by using the required command. Now I want to make some nodes gray/deative. To do so, I pick one node from first treeview and then in the other treeview all nodes that their node.Text are not equal with its text would be gray. I did it by the following function:

public void deactive_checkboxs(object sender, EventArgs e)
{
    TreeNodeCollection nodes_checked1 = treeView1.Nodes[0].LastNode.Nodes;
    TreeNodeCollection nodes_checked2 = treeView2.Nodes[0].LastNode.Nodes;

    foreach (TreeNode node1 in nodes_checked1)
    {
        if (node1.Checked)
        {
            foreach (TreeNode node2 in nodes_checked2)
            {
                if (node1.Text.Equals(node2.Text))
                {
                    node2.Checked = false;
                }
                else
                {
                    node2.Checked = false;
                }
             }
         }
    }
}

Of course this is not going to gray nodes rather would remove checked boxes behind the nodes( If you let me to know the making gray methods I would really appreciate it).

Now I do not know where should I put this function to have effect on the code. Does anyone help me?

Answer 1

This is not possible by simply setting a property.

You can neither disable a single Node nor remove its CheckBox.

Here is what you can do:

• You can change the ForeColor of each Node individually
• You can prevent changing the Checked state of any Node individually

Here is an example:

    treeView1.CheckBoxes = true;
    TreeNode tn = new TreeNode("Node 1");
    TreeNode tn1 = new TreeNode("Node 11");
    TreeNode tn2 = new TreeNode("Node 12");
    tn1.Checked = true;
    tn2.Checked = true;
    tn.Nodes.Add(tn1);
    tn.Nodes.Add(tn2);
    treeView1.Nodes.Add(tn);

    // gray text:
    tn2.ForeColor = Color.Gray;

    // mark one node somehow:
    tn2.Tag = "X";
    // cancel changes for marked node:
    treeView1.BeforeCheck += (s, e) 
        => { if (e.Node.Tag != null && e.Node.Tag.ToString() == "X") e.Cancel = true; };

To enable/disable a Node best use a function:

void SetNode(TreeNode node, bool enabled)
{
    node.ForeColor = enabled ? SystemColors.ControlText : Color.Gray;
    node.Tag = enabled ? null : "X";
}

To make the CheckBox look disabled you would have to owner-draw the node yourself. That is quite a bit of extra code..

First a few preparations:

    treeView1.DrawMode = TreeViewDrawMode.OwnerDrawAll;

    // cancel changes for marked node:
    treeView1.BeforeCheck += (s, e) 
        => { if (e.Node.Tag != null && e.Node.Tag.ToString() == "X") e.Cancel = true; };

    // a small correction;
    treeView1.AfterExpand += (s,e) => {treeView1.Refresh();};

And now for the actual drawing of the nodes:

    treeView1.DrawNode += (s, e)
        =>
        {
            if (e.Node.Tag == null || e.Node.Tag.ToString() != "X")
            { e.DrawDefault = true; return; }

            CheckBoxState cbsChDis = CheckBoxState.CheckedDisabled;
            CheckBoxState cbsUCDis = CheckBoxState.UncheckedDisabled;

            Size glyph = Size.Empty;
            glyph = CheckBoxRenderer.GetGlyphSize(e.Graphics, cbsChDis);

            Rectangle tBounds = e.Node.Bounds;  // the real bounds of the hittest area

            if (e.Node.IsSelected)
            {
                e.Graphics.FillRectangle(SystemBrushes.MenuHighlight, tBounds);
                e.Graphics.DrawString(e.Node.Text , Font, Brushes.White,
                                        tBounds.X , tBounds.Y);
            }
            else
            {
                CheckBoxRenderer.DrawParentBackground(e.Graphics, e.Bounds, this);
                e.Graphics.DrawString(e.Node.Text , Font, Brushes.Black,
                                        tBounds.X , tBounds.Y);
            }

            Point cBoxLocation = new Point(tBounds.Left - glyph.Width , tBounds.Top);
            CheckBoxState bs1 = e.Node.Checked ? cbsChDis : cbsUCDis;
            CheckBoxRenderer.DrawCheckBox(e.Graphics, cBoxLocation, bs1);

        };