C# using on-screen keyboard to fill up form

Question

I'm creating a winform application which require the windows on screen keyboard to fill up a text box. I have 4 text boxes. I created 4 textbox click event to pop up the keyboard when user click the textbox.

    public Form1()
    {
        InitializeComponent();

        textBox1.Click += textBox1_Click;
        textBox2.Click += textBox2_Click;
        textBox3.Click += textBox3_Click;
        textBox4.Click += textBox4_Click;
    }

    private void textBox1_Click(object sender, EventArgs e)
    {
        System.Diagnostics.Process.Start("osk");
    }

    private void textBox2_Click(object sender, EventArgs e)
    {
        System.Diagnostics.Process.Start("osk");
    }

    private void textBox3_Click(object sender, EventArgs e)
    {
        System.Diagnostics.Process.Start("osk");
    }

    private void textBox4_Click(object sender, EventArgs e)
    {
        System.Diagnostics.Process.Start("osk");
    }

The problem I face is, if I first click on textbox1 after running the app, the keyboard will only able to type into textbox1. After that if I click other textBox, it won't be able to type anything in.

Same as if I first click on textbox2 after running the app, the keyboard will only able to type into textbox2. After that if I click other textBox, it won't be able to type anything in.

Do you guys know what's wrong?

Answer 1

I would do something like this:

Add the following class to your project:

class TouchKeyboardProvider
{
    #region Private: Fields

    private readonly string _virtualKeyboardPath;

    #endregion

    #region ITouchKeyboardProvider Methods

    public TouchKeyboardProvider()
    {
        _virtualKeyboardPath = System.IO.Path.Combine(
            Environment.GetFolderPath(Environment.SpecialFolder.CommonProgramFiles),
            @"Microsoft Shared\ink\TabTip.exe");

        if (!System.IO.File.Exists(_virtualKeyboardPath))
        {
            _virtualKeyboardPath = _virtualKeyboardPath.Replace(" (x86)", string.Empty);
        }
    }

    public void ShowTouchKeyboard()
    {
        try
        {
            Process.Start(_virtualKeyboardPath);
        }
        catch (Exception ex)
        {
            // TODO: Log error.
            Debug.WriteLine(ex.ToString());
        }
    }

    public void HideTouchKeyboard()
    {
        var nullIntPtr = new IntPtr(0);
        const uint wmSyscommand = 0x0112;
        var scClose = new IntPtr(0xF060);

        var keyboardWnd = FindWindow("IPTip_Main_Window", null);
        if (keyboardWnd != nullIntPtr)
        {
            SendMessage(keyboardWnd, wmSyscommand, scClose, nullIntPtr);
        }
    }

    #endregion

    #region Private: Win32 API Methods

    [DllImport("user32.dll", CharSet = CharSet.Unicode)]
    private static extern IntPtr FindWindow(string sClassName, string sAppName);

    [DllImport("user32.dll", EntryPoint = "SendMessage", SetLastError = true)]
    private static extern IntPtr SendMessage(IntPtr hWnd, uint uMsg, IntPtr wParam, IntPtr lParam);

    #endregion

}

Then update your form to look something like this:

private readonly TouchKeyboardProvider touckKeyboardProvider = new TouchKeyboardProvider();

public Form1()
{
    InitializeComponent();

    textBox1.Click += textBox1_Click;
    textBox2.Click += textBox2_Click;
    textBox3.Click += textBox3_Click;
    textBox4.Click += textBox4_Click;
}

private void textBox1_Click(object sender, EventArgs e)
{
    touckKeyboardProvider.ShowTouchKeyboard();
}
....