WndProc WM_NCMOUSEUP no fire

Question

I've been trying to get a Form Border (title bar) mouse up for a bit now, and it seems like it's broken (I have found numerous other articles that state the same).

I have tested:

Const WM_LBUTTONUP = &H202
Const WM_MBUTTONUP = &H208
Const WM_RBUTTONUP = &H205
Const WM_NCXBUTTONUP = &HAC
Const WM_XBUTTONUP = &H20C
Const WM_MENURBUTTONUP = &H122
Const WM_NCLBUTTONUP = &HA2
Const WM_NCRBUTTONUP = &HA5
Const WM_NCLBUTTONDOWN = &HA1
Const WM_NCMOUSEMOVE = &HA0

quite thoroughly. What I am seeing is that, while WM_NCLBUTTONUP doesn't work, WM_NCLBUTTONDOWN does, and upon release (where I would expect the WM_NCLBUTTONUP), I get a WM_NCMOUSEMOVE instead. The issue being that you also get a WM_NCMOUSEMOVE as expected whenever you move the mouse outside of the client area (aka the form border)..

In a first attempt to overcome this, I have come up with:

Private MouseIsDown As Boolean = False
Protected Overrides Sub WndProc(ByRef m As Message)
    Const WM_NCLBUTTONDOWN = &HA1
    Const WM_NCMOUSEMOVE = &HA0
    If (m.Msg = WM_NCLBUTTONDOWN) Then
        MouseIsDown = True
        Console.WriteLine("NCLButtonDown")
    ElseIf (m.Msg = WM_NCMOUSEMOVE) Then
        If MouseIsDown Then
            Console.WriteLine("NCMouseMove" + Environment.NewLine + "LParam: " + m.LParam.ToString() + Environment.NewLine + "WParam: " + m.WParam.ToString() + Environment.NewLine + "Res: " + m.Result.ToString())
            MouseIsDown = False
        Else
            Console.WriteLine("Not mouseup")
        End If
    Else
    End If
    MyBase.WndProc(m)
End Sub

This seems to be working through initial testing, but I am curious if this would be appropriate, or if there is a message that I am simply missing (I have looked through: http://www.pinvoke.net/default.aspx/Constants.WM quite closely though, and don't see anything else that looks right).

Answer 1

You can use a NativeWindow or call WndProc on Form intance Code Translator | VB WindowsMessages

Try this:

    private NativeWnd _nativeWnd;

    private void Form1_Load(object sender, EventArgs e)
    {
        _nativeWnd = new NativeWnd(this);
    }

    class NativeWnd : NativeWindow, IDisposable
    {
        public NativeWnd(Form owner)
        {
            base.AssignHandle(owner.Handle);
        }

        private enum WindowMessages
        {
            // non client mouse
            WM_NCMOUSEMOVE = 0x00A0,
            WM_NCLBUTTONDOWN = 0x00A1,
            WM_NCLBUTTONUP = 0x00A2,
            WM_NCLBUTTONDBLCLK = 0x00A3,
            WM_NCRBUTTONDOWN = 0x00A4,
            WM_NCRBUTTONUP = 0x00A5,
            WM_NCRBUTTONDBLCLK = 0x00A6,
            WM_NCMBUTTONDOWN = 0x00A7,
            WM_NCMBUTTONUP = 0x00A8,
            WM_NCMBUTTONDBLCLK = 0x00A9,
        }


        private bool MouseIsDown;
        protected override void WndProc(ref Message m)
        {
            switch (m.Msg)
            {
                //Mouse Down
                case (int)WindowMessages.WM_NCLBUTTONDOWN:
                case (int)WindowMessages.WM_NCRBUTTONDOWN:
                case (int)WindowMessages.WM_NCMBUTTONDOWN:
                    MouseIsDown = true;
                    Debug.Write("NCMouseDown");
                    break;
                //MouseMove
                case (int)WindowMessages.WM_NCMOUSEMOVE:

                    if (MouseIsDown)
                    {
                        Debug.Write("NCMouseMove");
                        MouseIsDown = false;
                    }
                    break;
                //Mouse Up
                case (int)WindowMessages.WM_NCRBUTTONUP:
                case (int)WindowMessages.WM_NCLBUTTONUP:
                case (int)WindowMessages.WM_NCMBUTTONUP:
                    Debug.Write("NCMouseUp");
                    break;
                default:
                    base.WndProc(ref m);
                    break;
            }
        }

        #region IDisposable 

        public void Dispose()
        {
            base.ReleaseHandle();
        }

        #endregion
    }