How to disable a WinForms TreeView node checkbox?

Question

I need to be able to disable some of the checkboxes in a TreeView control of a WinForms application, but there\'s no such functionality built-in to the standard

Answer 1

This is PowerShell version, many thanks for @sam-trost for his life-savior code!

P/invoke:

$TypeDefinition = @'
using System;
using System.Runtime.InteropServices;
namespace Win32Functions {
    public class Win32TreeView {
        // constants used to hide a checkbox
        public const int TVIF_STATE = 0x8;
        public const int TVIS_STATEIMAGEMASK = 0xF000;
        public const int TV_FIRST = 0x1100;
        public const int TVM_SETITEM = TV_FIRST + 63;

        [DllImport("user32.dll", SetLastError = true)]
        public static extern IntPtr SendMessage(IntPtr hWnd, uint Msg, IntPtr wParam, IntPtr lParam);

        // struct used to set node properties
        public struct TVITEM
        {
            public int mask;
            public IntPtr hItem;
            public int state;
            public int stateMask;
            [MarshalAs(UnmanagedType.LPTStr)]
            public String lpszText;
            public int cchTextMax;
            public int iImage;
            public int iSelectedImage;
            public int cChildren;
            public IntPtr lParam;
        }
    }
}
'@

Add-Type -TypeDefinition $TypeDefinition -PassThru

Event handler:

$TreeView1_DrawNode = [System.Windows.Forms.DrawTreeNodeEventHandler]{
    #Event Argument: $_ = [System.Windows.Forms.DrawTreeNodeEventArgs]
    if ($null -ne $_.Node) {

        # P/invoke hack to hide Node CheckBox
        if ($_.Node.Level -eq 0) {
            Hide-NodeCheckBox($_.Node)
        }

        $_.DrawDefault = $true
    }
}

TreeView:

$TreeView1.DrawMode = [TreeViewDrawMode]::OwnerDrawText
$TreeView1.add_DrawNode($TreeView1_DrawNode)

Function:

function Hide-NodeCheckBox([TreeNode]$node) {
    # P/invoke hack to hide Node CheckBox
    if ($node.TreeView.CheckBoxes) {
        $tvi = [Win32Functions.Win32TreeView+TVITEM]::new()
        $tvi.hItem = $node.Handle
        $tvi.mask = [Win32Functions.Win32TreeView]::TVIF_STATE
        $tvi.stateMask = [Win32Functions.Win32TreeView]::TVIS_STATEIMAGEMASK
        $tvi.state = 0
        [IntPtr]$lparam = [Marshal]::AllocHGlobal([Marshal]::SizeOf($tvi))
        [Marshal]::StructureToPtr($tvi, $lparam, $false)
        [Win32Functions.Win32TreeView]::SendMessage($node.TreeView.Handle, [Win32Functions.Win32TreeView]::TVM_SETITEM, [IntPtr]::Zero, $lparam)
    }
}