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unregisterhotkey (user32)
 
.
Summary

C# Signature:

[DllImport("user32.dll", SetLastError = true)]
[return: MarshalAs(UnmanagedType.Bool)]
static extern bool UnregisterHotKey(IntPtr hWnd, int id);

VB.NET Signature:

Declare Auto Function UnregisterHotKey Lib "user32.dll" (ByVal hWnd As IntPtr, ByVal id As Integer) As Integer

User-Defined Types:

None.

Notes:

None.

Tips & Tricks:

Please add some!

Sample Code:

    // VB.NET
    Declare Auto Function RegisterHotKey Lib "user32.dll" (ByVal hWnd As IntPtr, ByVal id As Integer, _
        ByVal fsModifier As Integer, ByVal vk As Integer) As Integer
    Declare Auto Function UnregisterHotKey Lib "user32.dll" (ByVal hWnd As IntPtr, ByVal id As Integer) As Integer
    Declare Auto Function GlobalAddAtom Lib "kernel32.dll" (ByVal lpString As String) As UShort

    Private hotKeyID As Integer

    Private Sub Form1_FormClosing(ByVal sender As Object, ByVal e As System.Windows.Forms.FormClosingEventArgs) Handles Me.FormClosing
        UnregisterHotKey(Me.Handle, hotKeyID)
    End Sub

    Private Sub Form1_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
        hotKeyID = GlobalAddAtom("Form1HotKey")
        RegisterHotKey(Me.Handle, hotKeyID, 0, Keys.Escape)
    End Sub

    Protected Overrides Sub WndProc(ByRef m As Message)
        Const WM_HOTKEY As Integer = &H312

        Select Case m.Msg
            Case WM_HOTKEY
            Me.Close()
        End Select

        MyBase.WndProc(m)
    End Sub

    // 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);
        }

        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.RegisterHotKey(this);
        }
    }

Alternative Managed API:

The ManagedWindowsApi project (http://mwinapi.sourceforge.net) provides a

Hotkey class to register global hotkeys.

Documentation

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