How to create a universal keyboard shortcut?

Question

I have searched online for this, but can't find nothing at all. What I would like to do is to create a keyboard shortcut that I would be able to use in all applications. A universal keyboard shortcut, so that when I press, say Ctrl + Shift + X in any application, it would execute a piece of code I created in C#. For example, when I'm in Skype, I would select text and press Ctrl + Shift + X (or whatever other key combination), it would change the color of the text from black to blue. That is just an example to try and explain what I want to do. I'm thinking I would have to import a DLL and edit that (maybe user32.dll?) I'm just guessing. I have no clue how to do this, so any help will be greatly appreciated!

Thanks a lot in advance :)

PS: I am using Windows Forms Application, .NET Framework 4.0. Unclear about something I am trying to do/say? Please feel free to comment and I will get back to you right away.

Answer 1

Win32 has a RegisterHotKey function as part of the Win32 API. To use it in managed code (C#), you'd have to pInvoke it. Here is an example:

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;        
        keyId = f.GetHashCode(); // this should be a key unique ID, modify this if you want more than one hotkey
        RegisterHotKey((IntPtr)f.Handle, keyId, (uint)modifiers, (uint)k);
    }

    private delegate void Func();

    public static void UnregisterHotKey(Form f)
    {
        try
        {
            UnregisterHotKey(f.Handle, keyId); // modify this if you want more than one hotkey
        }
        catch (Exception ex)
        {
            MessageBox.Show(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);
    }
}

This code came from this article . Read that article for more information and more examples.