C# Signature:
/// <summary> The RegisterHotKey function defines a system-wide hot key </summary>
/// <param name="hwnd">Handle to the window that will receive WM_HOTKEY messages
/// generated by the hot key.</param>
/// <param name="id">Specifies the identifier of the hot key.</param>
/// <param name="fsModifiers">Specifies keys that must be pressed in combination with the key
/// specified by the 'vk' parameter in order to generate the WM_HOTKEY message.</param>
/// <param name="vk">Specifies the virtual-key code of the hot key</param>
/// <returns><c>true</c> if the function succeeds, otherwise <c>false</c></returns>
/// <seealso cref="http://msdn.microsoft.com/en-us/library/ms646309(VS.85).aspx"/>
[DllImport("user32.dll")]
[return: MarshalAs(UnmanagedType.Bool)]
static extern bool RegisterHotKey(IntPtr hWnd, int id, uint fsModifiers,
uint vk);
VB Signature:
Public Declare Function RegisterHotKey Lib "user32" Alias "RegisterHotKey" (ByVal hwnd As Long, ByVal id As Long, ByVal fsModifiers As Long, ByVal vk As Long) As Long
VB.net Signature:
Declare Auto Function registerhotkey Lib "user32.dll" (Byval handle As IntPtr, ByVal id As Integer, ByVal fsModifier As Integer, ByVal vk As Integer) As Integer
User-Defined Types:
None.
Notes:
None.
Tips & Tricks:
Please add some!
Sample Code:
// c#
public class WindowsShell
{
#region fields
public static int MOD_ALT = 0x1;
public static int MOD_CONTROL = 0x2;
public static int MOD_SHIFT = 0x4;
public static int MOD_WIN = 0x8;
public static int WM_HOTKEY = 0x312;
#endregion
[DllImport("user32.dll")]
private static extern bool RegisterHotKey(IntPtr hWnd, int id, int fsModifiers, int vlc);
[DllImport("user32.dll")]
private static extern bool UnregisterHotKey(IntPtr hWnd, int id);
private static int keyId;
public static void RegisterHotKey(Form f, Keys key)
{
int modifiers = 0;
if ((key & Keys.Alt) == Keys.Alt)
modifiers = modifiers | WindowsShell.MOD_ALT;
if ((key & Keys.Control) == Keys.Control)
modifiers = modifiers | WindowsShell.MOD_CONTROL;
if ((key & Keys.Shift) == Keys.Shift)
modifiers = modifiers | WindowsShell.MOD_SHIFT;
Keys k = key & ~Keys.Control & ~Keys.Shift & ~Keys.Alt;
Func ff = delegate()
{
keyId = f.GetHashCode(); // this should be a key unique ID, modify this if you want more than one hotkey
RegisterHotKey((IntPtr)f.Handle, keyId, modifiers, (int)k);
};
f.Invoke(ff); // this should be checked if we really need it (InvokeRequired), but it's faster this way
}
private delegate void Func();
public static void UnregisterHotKey(Form f)
{
try
{
Func ff = delegate()
{
UnregisterHotKey(f.Handle, keyId); // modify this if you want more than one hotkey
};
f.Invoke(ff); // this should be checked if we really need it (InvokeRequired), but it's faster this way
}
catch (Exception ex)
{
Debug.WriteLine(ex.ToString());
}
}
}
public partial class Form1 : Form, IDisposable
{
protected override void OnLoad(EventArgs e)
{
base.OnLoad(e);
Keys k = Keys.A | Keys.Control;
WindowsShell.RegisterHotKey(this, k);
}
// CF Note: The WndProc is not present in the Compact Framework (as of vers. 3.5)! please derive from the MessageWindow class in order to handle WM_HOTKEY
protected override void WndProc(ref Message m)
{
base.WndProc(ref m);
if (m.Msg == WindowsShell.WM_HOTKEY)
this.Visible = !this.Visible;
}
private void Form1_FormClosing(object sender, FormClosingEventArgs e)
{
WindowsShell.UnregisterHotKey(this);
}
}
Sample Code:
using System;
using System.Diagnostics;
using System.Runtime.InteropServices;
using System.Threading;
/// <summary> This class allows you to manage a hotkey </summary>
public class GlobalHotkeys : IDisposable
{
[DllImport( "user32", SetLastError = true )]
[return: MarshalAs( UnmanagedType.Bool )]
public static extern bool RegisterHotKey (IntPtr hwnd, int id, int fsModifiers, int vk);
[DllImport( "user32", SetLastError = true )]
public static extern int UnregisterHotKey (IntPtr hwnd, int id);
[DllImport( "kernel32", SetLastError = true )]
public static extern short GlobalAddAtom (string lpString);
[DllImport( "kernel32", SetLastError = true )]
public static extern short GlobalDeleteAtom (short nAtom);
public const int MOD_ALT = 1;
public const int MOD_CONTROL = 2;
public const int MOD_SHIFT = 4;
public const int MOD_WIN = 8;
public const int WM_HOTKEY = 0x312;
public GlobalHotkeys () {
this.Handle = Process.GetCurrentProcess().Handle;
}
/// <summary> handle of the current process </summary>
public IntPtr Handle;
/// <summary> the ID for the hotkey </summary>
public short HotkeyID {
get;
private set;
}
/// <summary> register the hotkey </summary>
public void RegisterGlobalHotKey (int hotkey, int modifiers, IntPtr handle) {
UnregisterGlobalHotKey();
this.Handle = handle;
RegisterGlobalHotKey( hotkey, modifiers );
}
/// <summary> register the hotkey </summary>
public void RegisterGlobalHotKey (int hotkey, int modifiers) {
UnregisterGlobalHotKey();
try {
// use the GlobalAddAtom API to get a unique ID (as suggested by MSDN docs)
string atomName = Thread.CurrentThread.ManagedThreadId.ToString( "X8" ) + this.GetType().FullName;
HotkeyID = GlobalAddAtom( atomName );
if ( HotkeyID == 0 )
throw new Exception( "Unable to generate unique hotkey ID. Error: " + Marshal.GetLastWin32Error().ToString() );
// register the hotkey, throw if any error
if ( !RegisterHotKey( this.Handle, HotkeyID, modifiers, (int) hotkey ) )
throw new Exception( "Unable to register hotkey. Error: " + Marshal.GetLastWin32Error().ToString() );
} catch ( Exception e ) {
// clean up if hotkey registration failed
UnregisterGlobalHotKey();
Console.WriteLine( e );
}
}
/// <summary> unregister the hotkey </summary>
public void UnregisterGlobalHotKey () {
if ( this.HotkeyID != 0 ) {
UnregisterHotKey( this.Handle, HotkeyID );
// clean up the atom list
GlobalDeleteAtom( HotkeyID );
HotkeyID = 0;
}
}
public void Dispose () {
UnregisterGlobalHotKey();
}
}
How to use :
GlobalHotkeys hotkey;
hotkey = new GlobalHotkeys();
hotkey.RegisterGlobalHotKey( (int) Keys.F11, GlobalHotkeys.MOD_CONTROL );
hotkey.UnregisterGlobalHotKey();
protected override void WndProc (ref Message m) {
const int WM_HOTKEY = 0x0312;
switch ( m.Msg ) {
case WM_HOTKEY:
if ( (short) m.WParam == hotkey.HotkeyID ) {
// do your thing
}
break;
default:
base.WndProc( ref m );
break;
}
}
Alternative Managed API:
The ManagedWindowsApi project (http://mwinapi.sourceforge.net) provides a
Hotkey class to register global hotkeys.
