羅羅亞的世界

註冊一個全區域的熱鍵，即是應用程式沒有被 focus 也能收到熱鍵。
網路上找到的通用類別，可輕易註冊想使用的 hotkey 然後自己寫對應的 handler

using System;
using windowcatch.ChatClient;
using System.Runtime.InteropServices;

namespace ChatClient
{
public delegate void HotkeyEventHandler(int HotKeyID);
///
/// System wide hotkey wrapper.
///
/// Robert Jeppesen
/// Send bugs to robert@durius.com
///
public class Hotkey : System.Windows.Forms.IMessageFilter
{
System.Collections.Hashtable keyIDs = new System.Collections.Hashtable();
IntPtr hWnd;
///
/// Occurs when a hotkey has been pressed.
///
public event HotkeyEventHandler OnHotkey;
public enum KeyFlags
{
MOD_ALT = 0x1,
MOD_CONTROL = 0x2,
MOD_SHIFT = 0x4,
MOD_WIN = 0x8
}
[System.Runtime.InteropServices.DllImport("user32.dll")]
public static extern UInt32 RegisterHotKey(IntPtr hWnd, UInt32 id,
UInt32 fsModifiers, UInt32 vk);
[System.Runtime.InteropServices.DllImport("user32.dll")]
public static extern UInt32 UnregisterHotKey(IntPtr hWnd, UInt32 id);
[System.Runtime.InteropServices.DllImport("kernel32.dll")]
public static extern UInt32 GlobalAddAtom(String lpString);
[System.Runtime.InteropServices.DllImport("kernel32.dll")]
public static extern UInt32 GlobalDeleteAtom(UInt32 nAtom);
///
/// Constructor. Adds this instance to the MessageFilters so that this class can raise Hotkey events
///
/// A valid hWnd, i.e. form1.Handle
public Hotkey(IntPtr hWnd)
{
this.hWnd = hWnd;
System.Windows.Forms.Application.AddMessageFilter(this);
}
///
/// Register a system wide hotkey.
///
/// form1.Handle
/// Your hotkey
/// ID integer for your hotkey. Use this to know which hotkey was pressed.
public int RegisterHotkey(System.Windows.Forms.Keys Key, KeyFlags keyflags)
{
UInt32 hotkeyid = GlobalAddAtom(System.Guid.NewGuid().ToString());
RegisterHotKey((IntPtr)hWnd, hotkeyid, (UInt32)keyflags, (UInt32)Key);
keyIDs.Add(hotkeyid, hotkeyid);
return (int)hotkeyid;
}
///
/// Unregister hotkeys and delete atoms.
///
public void UnregisterHotkeys()
{
System.Windows.Forms.Application.RemoveMessageFilter(this);
foreach (UInt32 key in keyIDs.Values)
{
UnregisterHotKey(hWnd, key);
GlobalDeleteAtom(key);
}
}
public bool PreFilterMessage(ref System.Windows.Forms.Message m)
{
if (m.Msg == 0x312) /*WM_HOTKEY*/
{
if (OnHotkey != null)
{
foreach (UInt32 key in keyIDs.Values)
{
if ((UInt32)m.WParam == key)
{
OnHotkey((int)m.WParam);
return true;
}
}
}
}
return false;
}
}
}

使用方法很簡單
Hotkey hotkey;  // 宣告類別            
hotkey = new Hotkey(this.Handle);  // 指定 this.Handle 給 hotkey 類別
int Hotkey1 = hotkey.RegisterHotkey(System.Windows.Forms.Keys.D1, Hotkey.KeyFlags.MOD_CONTROL);  // 註冊 ctrl+1 為全域熱鍵
hotkey.OnHotkey += new HotkeyEventHandler(OnHotkey);   // 指定熱鍵發生時的 handle function
接下來只要寫好 OnHotkey 要處理的事情就好。