Form WM_KEYDOWN and WM_KEYUP messages aren't captured in WndProc
c#, windows-messages, wndproc
Solution
You should override ProcessCmdKey instead
This example is extracted from this article
public partial class Form1 : Form, IMessageFilter
{
const int WM_KEYDOWN = 0x100;
const int WM_KEYUP = 0x101;
const int WM_SYSKEYDOWN = 0x104;
Keys lastKeyPressed = Keys.None;
public Form1()
{
InitializeComponent();
Application.AddMessageFilter(this);
this.FormClosed += (s, e) => Application.RemoveMessageFilter(this);
}
public bool PreFilterMessage(ref Message m)
{
if(m.Msg == WM_KEYUP)
{
Debug.WriteLine("Filter -> KeyUp LastKeyPressed=" + lastKeyPressed.ToString());
}
return false;
}
protected override bool ProcessCmdKey(ref Message msg, Keys keyData)
{
if ((msg.Msg == WM_KEYDOWN) || (msg.Msg == WM_SYSKEYDOWN))
{
lastKeyPressed = keyData;
switch (keyData)
{
case Keys.Down:
Debug.WriteLine("Down Arrow Captured");
break;
case Keys.Up:
Debug.WriteLine("Up Arrow Captured");
break;
case Keys.Tab:
Debug.WriteLine("Tab Key Captured");
break;
case Keys.Control | Keys.M:
Debug.WriteLine("<CTRL> + M Captured");
break;
case Keys.Alt | Keys.Z:
Debug.WriteLine("<ALT> + Z Captured");
break;
}
}
return base.ProcessCmdKey(ref msg, keyData);
}
Probably there is a way to extract the KeyCode from the message passed to the PreFilterMessage as explained in this article
Problem
Form keydown and keyup messages aren't captured: ``` public partial class Form1 : Form { const int WM_KEYDOWN = 0x100; const int WM_KEYUP = 0x101; protected override void WndProc(ref Message m) { if (m.Msg == WM_KEYDOWN) { log("down"); } if (m.Msg == WM_KEYUP) { log("up"); } base.WndProc(ref m); } } ```