Get KeyCode from a char?

Question

I need to be able to read a char and get it's Key relevant to it's language and keyboard layout.

I know how to see the cultural settings and languages. But how can i take a letter like 'S' in english and know what key it is on the keyboard? Or for a harder problem, how can i take the letter 'ש' and know what key it is on the keyboard?

Answer 1

This one might be more easily explained with an example program than anything else:

namespace KeyFinder
{
  class Program
  {
    [DllImport("user32.dll", CharSet = CharSet.Unicode)]
    static extern short VkKeyScanEx(char ch, IntPtr dwhkl);
    [DllImport("user32.dll")]
    static extern bool UnloadKeyboardLayout(IntPtr hkl);
    [DllImport("user32.dll")]
    static extern IntPtr LoadKeyboardLayout(string pwszKLID, uint Flags);
    public class KeyboardPointer : IDisposable
    {
      private readonly IntPtr pointer;
      public KeyboardPointer(int klid)
      {
        pointer = LoadKeyboardLayout(klid.ToString("X8"), 1);
      }
      public KeyboardPointer(CultureInfo culture)
        :this(culture.KeyboardLayoutId){}
      public void Dispose()
      {
        UnloadKeyboardLayout(pointer);
        GC.SuppressFinalize(this);
      }
      ~KeyboardPointer()
      {
        UnloadKeyboardLayout(pointer);
      }
      // Converting to System.Windows.Forms.Key here, but
      // some other enumerations for similar tasks have the same
      // one-to-one mapping to the underlying Windows API values
      public bool GetKey(char character, out Keys key)
      {
        short keyNumber = VkKeyScanEx(character, pointer);
        if(keyNumber == -1)
        {
          key = System.Windows.Forms.Keys.None;
          return false;
        }
        key = (System.Windows.Forms.Keys)(((keyNumber & 0xFF00) << 8) | (keyNumber & 0xFF));
        return true;
      }
    }
    private static string DescribeKey(Keys key)
    {
      StringBuilder desc = new StringBuilder();
      if((key & Keys.Shift) != Keys.None)
        desc.Append("Shift: ");
      if((key & Keys.Control) != Keys.None)
        desc.Append("Control: ");
      if((key & Keys.Alt) != Keys.None)
        desc.Append("Alt: ");
      return desc.Append(key & Keys.KeyCode).ToString();
    }
    public static void Main(string[] args)
    {
      string testChars = "Aéש";
      Keys key;
      foreach(var culture in (new string[]{"he-IL", "en-US", "en-IE"}).Select(code => CultureInfo.GetCultureInfo(code)))
      {
        Console.WriteLine(culture.Name);
        using(var keyboard = new KeyboardPointer(culture))
          foreach(char test in testChars)
          {
            Console.Write(test);
            Console.Write('\t');
            if(keyboard.GetKey(test, out key))
              Console.WriteLine(DescribeKey(key));
            else
              Console.WriteLine("No Key");
          }
      }
      Console.Read();//Stop window closing
    }
  }
}

Output:

he-IL
A  Shift: A
é  No Key
ש  A
en-US
A  Shift: A
é  No Key
ש  No Key
en-IE
A  Shift: A
é  Control: Alt: E
ש  No Key

(Though your own console might mess up ש and/or é depending on settings and fonts).

Note that the Windows kludge of using Ctrl+Alt as a substitute in case a keyboard has no AltGr key is precisely how it is reported, it's only at a lower level again that the two are treated as separate, which is one of the things that makes Windows keyboards less flexible (Alt + AltGr is meaningless in Windows).

Edit: The constructor for KeyboardPointer that takes a CultureInfo has obvious ease of use, but that which takes a number is useful for secondary keyboards for a given culture. E.g. en-US most often uses 0x0149, but there are variants with a different higher word (0x00010149, 0x00020149, 0x00030149, etc.) for variant layouts like Dvorak, extended support for characters (the so-called "International US" needed to write English words like "naïve", "façade" or "résumé"), and so on.

Answer 2

You can parse the KeyCode to determine if it containts the Letter you are searching for. For non english input i guess you will have to map these to english letters to know which key is it on the keyboard.