CODEWITHSUNDEEP
c#focusaccessibilitykeyboard-shortcutsstartup
CaptainNemo
CaptainNemo

Reputation: 1552

Maintaining focus on a form

I am developing a software for a blind individual in C# .NET.
The software works only with the keyboard and voice to speech.
When the computer starts the program is in the start up menu, but for some reason the program is activated not in focus therefore it does not work properly unless the focus is re transferred to it.

I found a way to hook keyboard keys even when the software is not in focus but I don't see that as a solution.

I want a way to do one or more of the following:

  1. Make sure the program loads on start up and is in focus.
  2. Maintain focus on the program (this computer will be run only using this program).
  3. Find a keyboard shortcut, preferably one key only (not Alt + Tab) to return focus to the program.

Upvotes: 0

Views: 848

Answers (1)

Silx
Silx

Reputation: 2701

There are many ways you can solve this ie you can run on startup console app that will run and focus your program:

    [STAThread]
    static void Main(string[] args)
    {
        System.Diagnostics.Process myProcess = new System.Diagnostics.Process();
        myProcess.StartInfo.FileName = "calc";
        myProcess.Start();
        IntPtr hWnd = myProcess.Handle;
        SetFocus(new HandleRef(null, hWnd));
    }

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

You can host a windows service application and using timer check if your app is alive and is focused or you can use hotkeys to bring it back focused: http://www.codeproject.com/KB/miscctrl/ashsimplehotkeys.aspx

Edited

this is console application, that will keep your app alive and focused (tested). i need to find walkaround for windows service becouse since vista something changed and form is invisible when stared from service :P

    static Process myProcess;

    [STAThread]
    static void Main(string[] args)
    {
        for (int i = 0; i < 10000; i++)
        {
            //count how many procesess with this name are active if more than zero its still alive
            Process[] proc = Process.GetProcessesByName("myprog");
            if (proc.Length > 0)
            {
                //its alive check if it has focus
                if (proc[0].MainWindowHandle != GetForegroundWindow())
                {
                    SetFocus(proc[0].MainWindowHandle);
                }
            }
            //no process start new one and focus on it
            else
            {
                myProcess = new Process();
                myProcess.StartInfo.FileName = "C:\\aa\\myprog.exe";
                myProcess.Start();

                SetFocus(myProcess.Handle);
            }
            Thread.Sleep(1000);
        }
    }

    private static void SetFocus(IntPtr handle)
    {
        SwitchToThisWindow(handle, true);
    }

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


    [DllImport("user32.dll", SetLastError = true)]
    public static extern void SwitchToThisWindow(IntPtr hWnd, bool fAltTab);

Upvotes: 3

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