【C#】【SHARE】The registering of global hotkeys

I remember that when I was still using VB6 sereval years ago, if global hotkeys are required, a massive system-hooking program would be used.

That's terrible,wasn't it? :)

But in C#, this can be much easier.We can use system api : RegisterHotKey and UnregisterHotKey(This links to the official document of Microsoft)

What to do next? Certianly is to encapsulate those function into a class in order to use it rapidly.(Thanks for Sir.bomo for his template,this is his page)

In the following class , the function ProcessKey is of great importance.

In the main form-class, a \(void\)  \(WndProc(ref\ Message\ m)\) is required,which used to processing the hotkey sends in.

Mention：The class \(keys\) is in \(System.Windows.Forms\), so surprising.

Code:(After you register the hotkey,press Ctrl+Alt+S to hide/show you window.)

 using System;
 using System.Collections.Generic;
 using System.ComponentModel;
 using System.Data;
 using System.Drawing;
 using System.Linq;
 using System.Text;
 using System.Threading.Tasks;
 using System.Windows.Forms;
 using System.Runtime;
 using System.Runtime.InteropServices;
 using System.Diagnostics;

 namespace WindowsFormsApplication1
 {
     public partial class Form1 : Form
     {
         HotKeys h = new HotKeys();

         public Form1()
         {
             InitializeComponent();
         }

         private void btnRegist_Click(object sender, EventArgs e)
         {
             if (h.Regist(this.Handle, (int)HotKeys.HotkeyModifiers.Shift + (int)HotKeys.HotkeyModifiers.Control, Keys.S, CallBack))
                 MessageBox.Show("Success");
             else MessageBox.Show("Failed");
         }
         private void btnUnregist_Click(object sender, EventArgs e)
         {
             if (h.UnRegist(this.Handle, CallBack))
                 MessageBox.Show("Success");
             else MessageBox.Show("Failed");
         }

         protected override void WndProc(ref Message m)
         {
             h.ProcessHotKey(m);  //Processing
             base.WndProc(ref m);
         }

         public void CallBack()
         {
             this.Visible = !this.Visible;
         }

         private void Form1_Load(object sender, EventArgs e)
         {

         }

     }

     public class HotKeys
     {

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

         private int keyid = ;
         private Dictionary<int, HotKeyCallBackHanlder> keymap = new Dictionary<int, HotKeyCallBackHanlder>();
         public delegate void HotKeyCallBackHanlder();
         private const int WM_HOTKEY = 0x312;

         public enum HotkeyModifiers
         {
             Alt = ,
             Control = ,
             Shift = ,
             Win =
         }

         public bool Regist(IntPtr hWnd, int modifiers, Keys vk, HotKeyCallBackHanlder callBack)  //Regist Hotkey
         {
             try
             {
                 int id = keyid++;
                 if (!RegisterHotKey(hWnd, id, modifiers, vk)) return false;
                 keymap[id] = callBack;
             }
             catch { return false; }  //make the class stronger
             return true;
         }

         public bool UnRegist(IntPtr hWnd, HotKeyCallBackHanlder callBack)  //UnRegister hotkey
         {
             bool bx = false;
             foreach (KeyValuePair<int, HotKeyCallBackHanlder> var in keymap)
             {
                 if (var.Value == callBack)
                 {
                     try
                     {
                         UnregisterHotKey(hWnd, var.Key);
                         keymap.Remove(var.Key);  //I think this line is important,which the original author not add.
                     }
                     catch { }
                     bx = true;
                 }
             }
             return bx;

         }

         public void ProcessHotKey(Message m)   //Processing and React
         {
             if (m.Msg == WM_HOTKEY) //The original author puts 0x312 here.WM_HOTKEY can be clearer.
             {
                 int id = m.WParam.ToInt32();
                 HotKeyCallBackHanlder callback;
                 if (keymap.TryGetValue(id, out callback))
                     callback();
             }
         }
     }
 }