HardTop/NativeMethods.cs at master · voltura/HardTop · GitHub

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#region Using statements

using System;
using System.Collections;
using System.Collections.Generic;
using System.Runtime.InteropServices;
using System.Text;

#endregion Using statements

namespace HardTop
{
    internal static class NativeMethods
    {
        #region Private constants used in user32 API's interaction

        private const int WS_EX_TOPMOST = 0x00000008;
        private const int GWL_EXSTYLE = -20;

        #endregion Private constants used in user32 API's interaction

        #region Private variables

        private static List<IntPtr> WindowHandles;
        private static List<string> WindowTitles;

        #endregion Private variables

        #region Delegates used in user32 API's interaction

        private delegate bool EnumWindowsProc(IntPtr hwnd, ArrayList lParam);
        private delegate bool EnumDelegate(IntPtr hWnd, int lParam);

        #endregion Delegates used in user32 API's interaction

        #region Internal functions for Window handling

        internal static void GetDesktopWindowHandlesAndTitles(out List<IntPtr> handles, out List<string> titles)
        {
            WindowHandles = new List<IntPtr>();
            WindowTitles = new List<string>();
            if (!EnumDesktopWindows(IntPtr.Zero, GetDesktopWindowHandlesAndTitlesFilterCallback, IntPtr.Zero))
            {
                handles = null;
                titles = null;
            }
            else
            {
                handles = WindowHandles;
                titles = WindowTitles;
            }
        }

        internal static ArrayList AlwaysOnTopWindows()
        {
            var topmostWindowHandles = new ArrayList();
            EnumWindows(EnumWindowsCallback, topmostWindowHandles);
            return topmostWindowHandles;
        }

        internal static void ToggleWindowAlwaysOnTop(IntPtr hwnd, bool alwaysOnTop)
        {
            SetWindowPos(hwnd, (IntPtr)(alwaysOnTop ? -1 : -2), 0, 0, 0, 0, 67);
        }

        #endregion Internal functions for Window handling

        #region Private Callback methods; window handling

        private static bool EnumWindowsCallback(IntPtr hWnd, ArrayList lParam)
        {
            int exStyle = GetWindowLong(hWnd, GWL_EXSTYLE);
            if ((exStyle & WS_EX_TOPMOST) == WS_EX_TOPMOST) lParam.Add(hWnd);
            return true;
        }

        private static bool GetDesktopWindowHandlesAndTitlesFilterCallback(IntPtr hWnd, int lParam)
        {
            StringBuilder sb_title = new StringBuilder(1024);
            GetWindowText(hWnd, sb_title, sb_title.Capacity);
            string title = sb_title.ToString();
            if (IsWindowVisible(hWnd) && string.IsNullOrEmpty(title) == false)
            {
                WindowHandles.Add(hWnd);
                WindowTitles.Add(title);
            }
            return true;
        }

        #endregion Private Callback methods; window handling

        #region user32.dll function imports; window handling

        [DllImport("user32.dll")]
        [return: MarshalAs(UnmanagedType.Bool)]
        private static extern bool EnumWindows(EnumWindowsProc lpEnumFunc, ArrayList lParam);

        [DllImport("user32.dll")]
        private static extern uint GetWindowThreadProcessId(IntPtr hWnd, out uint lpdwProcessId);

        [DllImport("user32.dll")]
        private static extern int GetWindowLong(IntPtr hWnd, int nIndex);

        [DllImport("user32.dll")]
        [return: MarshalAs(UnmanagedType.Bool)]
        private static extern bool SetWindowPos(IntPtr hWnd, IntPtr hWndInsertAfter, int x, int y, int cx, int xy, uint flagsw);

        [DllImport("user32.dll")]
        [return: MarshalAs(UnmanagedType.Bool)]
        private static extern bool IsWindowVisible(IntPtr hWnd);

        [DllImport("user32.dll", EntryPoint = "GetWindowText",
        ExactSpelling = false, CharSet = CharSet.Auto, SetLastError = true)]
        internal static extern int GetWindowText(IntPtr hWnd, StringBuilder lpWindowText, int nMaxCount);

        [DllImport("user32.dll", EntryPoint = "EnumDesktopWindows",
        ExactSpelling = false, CharSet = CharSet.Auto, SetLastError = true)]
        private static extern bool EnumDesktopWindows(IntPtr hDesktop, EnumDelegate lpEnumCallbackFunction, IntPtr lParam);

        #endregion user32.dll function imports; window handling

        #region user32.dll function import; used to free GDI+ icon from memory

        [DllImport("user32.dll", CharSet = CharSet.Auto)]
        [return: MarshalAs(UnmanagedType.Bool)]
        internal static extern bool DestroyIcon(IntPtr handle);

        #endregion user32.dll function import; used to free GDI+ icon from memory
    }
}