Mega Code Archive

 

Categories / C# / GUI Windows Form

 

Set focus to the previous instance of the specified program

using System; using System.Diagnostics; using System.Threading; using System.Windows.Forms; using System.Runtime.InteropServices; namespace ReportViewer {     /// Summary description for ProcessUtils.     public static class ProcessUtils     {         private static Mutex mutex = null;         /// Determine if the current process is already running         public static bool ThisProcessIsAlreadyRunning()         {             // Only want to call this method once, at startup.             Debug.Assert(mutex == null);             // createdNew needs to be false in .Net 2.0, otherwise, if another instance of             // this program is running, the Mutex constructor will block, and then throw              // an exception if the other instance is shut down.             bool createdNew = false;             mutex = new Mutex(false, Application.ProductName, out createdNew);             Debug.Assert(mutex != null);             return !createdNew;         }         [DllImport("user32.dll", SetLastError = true)]         static extern IntPtr FindWindow(string lpClassName, string lpWindowName);         [DllImport("user32.dll")]         [return: MarshalAs(UnmanagedType.Bool)]         static extern bool SetForegroundWindow(IntPtr hWnd);         [DllImport("user32.dll")]         static extern bool IsIconic(IntPtr hWnd);         [DllImport("user32.dll")]         static extern bool ShowWindow(IntPtr hWnd, int nCmdShow);         const int SW_RESTORE = 9;         [DllImport("user32.dll")]         static extern IntPtr GetLastActivePopup(IntPtr hWnd);         [DllImport("user32.dll")]         static extern bool IsWindowEnabled(IntPtr hWnd);         /// Set focus to the previous instance of the specified program.         public static void SetFocusToPreviousInstance(string windowCaption)         {             // Look for previous instance of this program.             IntPtr hWnd = FindWindow(null, windowCaption);             // If a previous instance of this program was found...             if (hWnd != null)             {                 // Is it displaying a popup window?                 IntPtr hPopupWnd = GetLastActivePopup(hWnd);                 // If so, set focus to the popup window. Otherwise set focus                 // to the program's main window.                 if (hPopupWnd != null && IsWindowEnabled(hPopupWnd))                 {                     hWnd = hPopupWnd;                 }                 SetForegroundWindow(hWnd);                 // If program is minimized, restore it.                 if (IsIconic(hWnd))                 {                     ShowWindow(hWnd, SW_RESTORE);                 }             }         }     } }