Make minimized/system tray application gui visible from c#

Question

I have a windows form application that opens another vendor's application. If the vendor's application is not running, my code opens it and it becomes visible as expected. However, if the vendor's application is already running minimized or in the system tray, I can't make it visible when I call Process.Start(). Is there a way to make a currently running application visible/shown whether if it is minimized or in the system tray?

This is my code to open the other application which only works if the VendorProgram.exe is not running. If VendorProgram.exe is running but minimized it doesn't make it visible/shown, which is what I need.

ProcessStartInfo startInfo = new ProcessStartInfo();
startInfo.CreateNoWindow = false;
startInfo.UseShellExecute = false;
startInfo.FileName = "C:\\Program Files (x86)\\VendorProgram.exe";
startInfo.WindowStyle = ProcessWindowStyle.Normal;


Process p = Process.Start(startInfo);

EDIT: In case it isn't clear, I am not trying to make an application open itself, I am trying to open a separate vendor's application from my application.

Answer 1

First of all, you are somewhat trying to reinvent the wheel. As Steve pointed out in the comments, there are already built-in methods for achieving a single-instance application, such as with a Mutex.

The "show it when it is minimized to the tray" part is the tricky one, however.

You could loop over running processes to find yours, and then optionally start a new one, or call up the already running one. This requires a little p/invoke magic:

[DllImport("user32.dll")]
private static extern IntPtr FindWindow(String lpClassName, String lpWindowName);
[DllImport("user32.dll")]
private static extern Boolean SetForegroundWindow(IntPtr hWnd);
[DllImport("user32.dll")]
public static extern Boolean ShowWindow(IntPtr hWnd, Int32 nCmdShow);

var bFound = false;
foreach (var proc in Process.GetProcesses())
{
    if (proc.ProcessName.Equals("YourProcessName"))
    {
        var window = FindWindow(null, proc.MainWindowTitle);
        if (!window.Equals(IntPtr.Zero))
        {
            //Mixed results...this might be redundant
            SetForegroundWindow(window);
            ShowWindow(window, 1);  //SW_NORMAL
            bFound =true;
        }
    }
}

if (!bFound)
{
    var startInfo = new ProcessStartInfo();
    startInfo.CreateNoWindow = false;
    startInfo.UseShellExecute = false;
    startInfo.FileName = "C:\\Program Files (x86)\\Program.exe";
    startInfo.WindowStyle = ProcessWindowStyle.Normal;
    Process.Start(startInfo);
}

Answer 2

I found this and it helped me do what I needed.

The trick was to use the correct window name in FindWindow() not process.MainWindowTitle. Apparently, process.MainWindowTitle brings back the first window created by the application. That might work sometimes but not always. I needed to put the name of the actual window that was minimized in the system tray. Using notepad for example, if the title was my file - Notepad, that's what you need to put in FindWindow. This seems clumsy but works everytime for me. Notepad isn't the application I'm opening but it's for example.

This doesn't work

foreach (var proc in Process.GetProcesses()) {
    if (proc.ProcessName.Equals("Notepad"))
    {
      IntPtr window = FindWindow(null, proc.MainWindowTitle);    
      ShowWindow(hWnd, 1);
      break;
    }
 }

this does

  IntPtr window = FindWindow(null, "my file - Notepad");   
  ShowWindow(hWnd, 1); 

Answer 3

did you try using

[DllImport("user32.dll")]
private static extern bool ShowWindowAsync(IntPtr hWnd, int nCmdShow);

instead of "ShowWindow(IntPtr hWnd, int nCmdShow)"?