Detect active window changed using C# with a console application

Question

This question is very similar to this one (Detect active window changed using C# without polling), and the code on that accepted answer works fine with a Windows Forms Application, but no way with a Console Application.

¿How can I detect that active window has changed without doing infinite iterations (or any type of polling) with a Console Application?

Thanks in advance.

Answer 1

It can be changed to run as a console application with a few changes. Here is a working code.

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

namespace ConsoleApplication1
{
    class Program
    {
        static void Main(string[] args)
        {
            dele = new WinEventDelegate(WinEventProc);
            IntPtr m_hhook = SetWinEventHook(EVENT_SYSTEM_FOREGROUND, EVENT_SYSTEM_FOREGROUND, IntPtr.Zero, dele, 0, 0, WINEVENT_OUTOFCONTEXT);
            Application.Run(); //<----
        }

        static WinEventDelegate dele = null; //STATIC

        delegate void WinEventDelegate(IntPtr hWinEventHook, uint eventType, IntPtr hwnd, int idObject, int idChild, uint dwEventThread, uint dwmsEventTime);

        [DllImport("user32.dll")]
        static extern IntPtr SetWinEventHook(uint eventMin, uint eventMax, IntPtr hmodWinEventProc, WinEventDelegate lpfnWinEventProc, uint idProcess, uint idThread, uint dwFlags);

        private const uint WINEVENT_OUTOFCONTEXT = 0;
        private const uint EVENT_SYSTEM_FOREGROUND = 3;

        [DllImport("user32.dll")]
        static extern IntPtr GetForegroundWindow();

        [DllImport("user32.dll")]
        static extern int GetWindowText(IntPtr hWnd, StringBuilder text, int count);

        private static string GetActiveWindowTitle() //STATIC
        {
            const int nChars = 256;
            IntPtr handle = IntPtr.Zero;
            StringBuilder Buff = new StringBuilder(nChars);
            handle = GetForegroundWindow();

            if (GetWindowText(handle, Buff, nChars) > 0)
            {
                return Buff.ToString();
            }
            return null;
        }

        public static void WinEventProc(IntPtr hWinEventHook, uint eventType, IntPtr hwnd, int idObject, int idChild, uint dwEventThread, uint dwmsEventTime) //STATIC
        {
            Console.WriteLine(GetActiveWindowTitle());
        }
    }
}