Autosize witdth of treeview after collapse

Question

I'm looking for a way to set the width of a treeview to either it's max, or to the size of the longest treenode in it, whenever a node is being collapsed or opened.

I've tried using the clientsize, but that doesn't seem to work. Is there a different way to check which node is the longest and set the TreeView.Width to that size?

Answer 1

After some more searching on the net I found this way:

private const int GWL_STYLE = -16;
private const int WS_VSCROLL = 0x00200000;
private const int WS_HSCROLL = 0x00100000;


[DllImport("user32.dll", ExactSpelling = false, CharSet = CharSet.Auto)]
private static extern int GetWindowLong(IntPtr hWnd, int nIndex);

and:

//tree = instance of a treeview
tree.AfterExpand += (s, ea) =>
{
    int style = GetWindowLong(tree.Handle, GWL_STYLE);
    while ((style & WS_HSCROLL) != 0)
    {
        tree.Width++;
        style = GetWindowLong(tree.Handle, GWL_STYLE);
    }
};

Ofcourse you can use this on a button aswell!