Shortcut Key using C#

Question

I want to create a simple application that having a send keys (like a shortcut keys). The case is, whenever the created application is inactive window, The system still recognize the pressed keys of the user as long as the system is running.

In short, It is simply like pressing (window + D) that show your desktop immediately whenever on what application/window are you in.

Can anyone help me on how can I do this in C# 2005

Answer 1

Use the following:

[DllImport("user32.dll")]
private static extern bool RegisterHotKey(IntPtr hWnd, int id, uint fsModifiers, uint vk);
[DllImport("user32.dll")]
private static extern bool UnregisterHotKey(IntPtr hWnd, int id);

and

[Flags]
public enum ModifierKeys : uint
{
    Alt = 1,
    Control = 2,
    Shift = 4,
    Win = 8
}

private ModifierKeys _getModifierKeys(bool isAlt, bool isCtrl, bool isShift, bool isWin)
{
    return (isAlt ? ModifierKeys.Alt : 0) |
            (isCtrl ? ModifierKeys.Control : 0) |
            (isShift ? ModifierKeys.Shift : 0) |
            (isWin ? ModifierKeys.Win : 0);
}

then, to register your hotkey,

RegisterHotKey(hWndNotify, id,
                    (uint)_getModifierKeys(_isAlt, _isCtrl, _isShift, _isWin),
                    (uint)_key);

in the host hWnd, listen for WM_HOTKEYREADY, then check for matches to your hotkey using

public bool Matches(ref Message m)
{
    Keys key = (Keys)(((int)m.LParam >> 16) & 0xFFFF);
    ModifierKeys modifier = (ModifierKeys)((int)m.LParam & 0xFFFF);

    if ((key == Key) &&
        (modifier == Modifier))
    {
        return true;
    }

    return false;
}