How do I suspend painting for a control and its children?

Question

I have a control which I have to make large modifications to. I\'d like to completely prevent it from redrawing while I do that - SuspendLayout and ResumeLayout aren\'t eno

Answer 1

I know this is an old question, already answered, but here is my take on this; I refactored the suspension of updates into an IDisposable - that way I can enclose the statements I want to run in a using statement.

class SuspendDrawingUpdate : IDisposable
{
    private const int WM_SETREDRAW = 0x000B;
    private readonly Control _control;
    private readonly NativeWindow _window;

    public SuspendDrawingUpdate(Control control)
    {
        _control = control;

        var msgSuspendUpdate = Message.Create(_control.Handle, WM_SETREDRAW, IntPtr.Zero, IntPtr.Zero);

        _window = NativeWindow.FromHandle(_control.Handle);
        _window.DefWndProc(ref msgSuspendUpdate);
    }

    public void Dispose()
    {
        var wparam = new IntPtr(1);  // Create a C "true" boolean as an IntPtr
        var msgResumeUpdate = Message.Create(_control.Handle, WM_SETREDRAW, wparam, IntPtr.Zero);

        _window.DefWndProc(ref msgResumeUpdate);

        _control.Invalidate();
    }
}