Dalamud/Dalamud/NativeFunctions.cs

using System;
using System.Diagnostics;
using System.Runtime.InteropServices;
using System.Text;

#pragma warning disable SA1600 // Elements should be documented
#pragma warning disable SA1602 // Enumeration items should be documented

namespace Dalamud
{
    internal static class NativeFunctions
    {
        public enum FlashWindow : uint
        {
            /// <summary>
            /// Stop flashing. The system restores the window to its original state.
            /// </summary>
            FLASHW_STOP = 0,

            /// <summary>
            /// Flash the window caption
            /// </summary>
            FLASHW_CAPTION = 1,

            /// <summary>
            /// Flash the taskbar button.
            /// </summary>
            FLASHW_TRAY = 2,

            /// <summary>
            /// Flash both the window caption and taskbar button.
            /// This is equivalent to setting the FLASHW_CAPTION | FLASHW_TRAY flags.
            /// </summary>
            FLASHW_ALL = 3,

            /// <summary>
            /// Flash continuously, until the FLASHW_STOP flag is set.
            /// </summary>
            FLASHW_TIMER = 4,

            /// <summary>
            /// Flash continuously until the window comes to the foreground.
            /// </summary>
            FLASHW_TIMERNOFG = 12,
        }

        [Flags]
        public enum ErrorModes : uint
        {
            SYSTEM_DEFAULT = 0x0,
            SEM_FAILCRITICALERRORS = 0x0001,
            SEM_NOALIGNMENTFAULTEXCEPT = 0x0004,
            SEM_NOGPFAULTERRORBOX = 0x0002,
            SEM_NOOPENFILEERRORBOX = 0x8000,
        }

        /// <summary>Returns true if the current application has focus, false otherwise.</summary>
        /// <returns>If the current application is focused.</returns>
        public static bool ApplicationIsActivated()
        {
            var activatedHandle = GetForegroundWindow();
            if (activatedHandle == IntPtr.Zero)
            {
                return false;       // No window is currently activated
            }

            var procId = Process.GetCurrentProcess().Id;
            GetWindowThreadProcessId(activatedHandle, out var activeProcId);

            return activeProcId == procId;
        }

        [DllImport("user32.dll", CharSet = CharSet.Auto, ExactSpelling = true)]
        public static extern IntPtr GetForegroundWindow();

        [DllImport("user32.dll", CharSet = CharSet.Auto, SetLastError = true)]
        public static extern int GetWindowThreadProcessId(IntPtr handle, out int processId);

        [DllImport("user32.dll")]
        [return: MarshalAs(UnmanagedType.Bool)]
        public static extern bool FlashWindowEx(ref FLASHWINFO pwfi);

        [DllImport("kernel32.dll", SetLastError = true)]
        [return: MarshalAs(UnmanagedType.Bool)]
        public static extern bool FreeLibrary(IntPtr hModule);

        [DllImport("kernel32.dll", CharSet = CharSet.Auto)]
        public static extern IntPtr GetModuleHandle(string lpModuleName);

        [DllImport("kernel32.dll", SetLastError = true)]
        [PreserveSig]
        public static extern uint GetModuleFileName(
            [In] IntPtr hModule,
            [Out] StringBuilder lpFilename,
            [In][MarshalAs(UnmanagedType.U4)] int nSize);

        [DllImport("kernel32", SetLastError = true, CharSet = CharSet.Ansi)]
        public static extern IntPtr LoadLibrary([MarshalAs(UnmanagedType.LPStr)] string lpFileName);

        [DllImport("kernel32.dll")]
        public static extern IntPtr SetUnhandledExceptionFilter(IntPtr lpTopLevelExceptionFilter);

        [DllImport("kernel32.dll")]
        public static extern ErrorModes SetErrorMode(ErrorModes uMode);

        [DllImport("kernel32.dll", SetLastError = true)]
        public static extern bool DebugActiveProcess(uint dwProcessId);

#pragma warning disable SA1307 // Accessible fields should begin with upper-case letter
#pragma warning disable SA1121 // Use built-in type alias

        [StructLayout(LayoutKind.Sequential)]
        public struct FLASHWINFO
        {
            public UInt32 cbSize;
            public IntPtr hwnd;
            public FlashWindow dwFlags;
            public UInt32 uCount;
            public UInt32 dwTimeout;
        }

#pragma warning restore SA1121 // Use built-in type alias
#pragma warning restore SA1307 // Accessible fields should begin with upper-case letter
    }
}

#pragma warning restore SA1600 // Elements should be documented
#pragma warning restore SA1602 // Enumeration items should be documented