BanksySan BanksySan - 28 days ago 12
C# Question

Capture user key at any time in Console application

I have a console application, I know how to capture user input but I'd like the user to be able to press

Ctrl+X
at any time and capture it (to reset the application).

How can I capture any user input?

Elaboration

There are three input methods on the
Console
object:


  • int Read()

  • int ReadKey()

  • string ReadLine()



I need to be able to capture normal user input, that being characters and have those display as the user types.

Additionally, at any time, the user can press
Ctrl+X
which will invoke a
Reset()
method.

Answer

Original code for HotKeyManager is from this post: Global keyboard capture in C# application

using System;
using System.Windows.Forms;
using System.Runtime.InteropServices;
using System.Threading;

namespace ConsoleHotKey
{
    public static class HotKeyManager
    {
        public static event EventHandler<HotKeyEventArgs> HotKeyPressed;

        public static int RegisterHotKey(Keys key, KeyModifiers modifiers)
        {
            _windowReadyEvent.WaitOne();
            int id = System.Threading.Interlocked.Increment(ref _id);
            _wnd.Invoke(new RegisterHotKeyDelegate(RegisterHotKeyInternal), _hwnd, id, (uint)modifiers, (uint)key);
            return id;
        }

        public static void UnregisterHotKey(int id)
        {
            _wnd.Invoke(new UnRegisterHotKeyDelegate(UnRegisterHotKeyInternal), _hwnd, id);
        }

        delegate void RegisterHotKeyDelegate(IntPtr hwnd, int id, uint modifiers, uint key);
        delegate void UnRegisterHotKeyDelegate(IntPtr hwnd, int id);

        private static void RegisterHotKeyInternal(IntPtr hwnd, int id, uint modifiers, uint key)
        {
            RegisterHotKey(hwnd, id, modifiers, key);
        }

        private static void UnRegisterHotKeyInternal(IntPtr hwnd, int id)
        {
            UnregisterHotKey(_hwnd, id);
        }

        private static void OnHotKeyPressed(HotKeyEventArgs e)
        {
            if (HotKeyManager.HotKeyPressed != null)
            {
                HotKeyManager.HotKeyPressed(null, e);
            }
        }

        private static volatile MessageWindow _wnd;
        private static volatile IntPtr _hwnd;
        private static ManualResetEvent _windowReadyEvent = new ManualResetEvent(false);
        static HotKeyManager()
        {
            Thread messageLoop = new Thread(delegate()
            {
                Application.Run(new MessageWindow());
            });
            messageLoop.Name = "MessageLoopThread";
            messageLoop.IsBackground = true;
            messageLoop.Start();
        }

        private class MessageWindow : Form
        {
            public MessageWindow()
            {
                _wnd = this;
                _hwnd = this.Handle;
                _windowReadyEvent.Set();
            }

            protected override void WndProc(ref Message m)
            {
                if (m.Msg == WM_HOTKEY)
                {
                    HotKeyEventArgs e = new HotKeyEventArgs(m.LParam);
                    HotKeyManager.OnHotKeyPressed(e);
                }

                base.WndProc(ref m);
            }

            protected override void SetVisibleCore(bool value)
            {
                // Ensure the window never becomes visible
                base.SetVisibleCore(false);
            }

            private const int WM_HOTKEY = 0x312;
        }

        [DllImport("user32", SetLastError = true)]
        private static extern bool RegisterHotKey(IntPtr hWnd, int id, uint fsModifiers, uint vk);

        [DllImport("user32", SetLastError = true)]
        private static extern bool UnregisterHotKey(IntPtr hWnd, int id);

        private static int _id = 0;
    }


    public class HotKeyEventArgs : EventArgs
    {
        public readonly Keys Key;
        public readonly KeyModifiers Modifiers;

        public HotKeyEventArgs(Keys key, KeyModifiers modifiers)
        {
            this.Key = key;
            this.Modifiers = modifiers;
        }

        public HotKeyEventArgs(IntPtr hotKeyParam)
        {
            uint param = (uint)hotKeyParam.ToInt64();
            Key = (Keys)((param & 0xffff0000) >> 16);
            Modifiers = (KeyModifiers)(param & 0x0000ffff);
        }
    }

    [Flags]
    public enum KeyModifiers
    {
        Alt = 1,
        Control = 2,
        Shift = 4,
        Windows = 8,
        NoRepeat = 0x4000
    }
}

And here is usage for your request:

using System;
using System.Diagnostics;
using System.Windows.Forms;
using System.Runtime.InteropServices;
using ConsoleHotKey;

namespace ConsoleTester
{
    class Program
    {
        static bool exitApp = false;

        static void Main(string[] args)
        {
            HotKeyManager.RegisterHotKey(Keys.X, KeyModifiers.Control);
            HotKeyManager.HotKeyPressed += new EventHandler<HotKeyEventArgs>(HotKeyManager_HotKeyPressed);

            //this loop is only to keep app from exiting...
            while (!exitApp)
            {
                Console.WriteLine("Press Ctrl+X to exit!");
                System.Threading.Thread.Sleep(1000);


                //TODO: write you code...
            }
        }

        static void HotKeyManager_HotKeyPressed(object sender, HotKeyEventArgs e)
        {


            Console.WriteLine("Aplication will exit!");

            //TODO: restart yor app or in this case force exit...

            exitApp = true;
        }
    }


}

Here is additonal code how you can restart your app:

        System.Diagnostics.ProcessStartInfo Info = new System.Diagnostics.ProcessStartInfo();
        Info.FileName = System.Reflection.Assembly.GetEntryAssembly().Location;
        System.Diagnostics.Process.Start(Info);
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