Question

I would like to simulate shortcuts for a remote control feature of our Windows Mobile application. Any possible shortcut should be supported (think of Ctrl+/ or Alt+ä).

With keybd_event I can simulate shortcuts very well, but only Virtual-Key Codes are allowed with this function. Therefore, I thought of the PostKeybdMessage function which allows me to send any character to the foreground window. But if I combine the two calls, Windows will just print the character instead of executing the shortcut.

Here’s what I tried:

• Sending the CTRL key silently (KEYEVENTF_SILENT)
• Adding the KeyShiftAnyCtrlFlag to the PostKeybdMessage call
• Played a lot with the buffers and the flags of the PostKeybdMessage call (which is quite confusing)

My questions are:

• Can PostKeybdMessage be used to simulate shortcuts or am I just wasting my time? If it can, what did I do wrong in the code sample?
• Is there maybe a trick to send special characters (umlauts, #, =, …) with keybd_event?
• Is there another way to simulate a shortcut?

Simple test application

public partial class ShortcutTest : Form
{
  private const int KEYEVENTF_KEYUP = 0x0002;
  private const int HWND_FOREGROUND = -1;

  private const uint KEY_STATE_DOWN = 0x0080;
  private const uint KEY_SHIFT_NO_CHARACTER = 0x00010000;
  private const uint KEY_SHIFT_ANY_CONTROL = 0x40000000;

  private const byte VK_CONTROL = 0x11; // Keys.ControlKey

  [DllImport("coredll.dll", SetLastError = true)]
  internal static extern void keybd_event(byte bVk, byte bScan, int dwFlags, int dwExtraInfo);

  [DllImport("coredll.dll")]
  private static extern bool PostKeybdMessage(int hwnd, uint vKey, uint KeyStateFlags, uint cCharacters, uint[] pShiftStateBuffer, uint[] pCharacterBuffer);

  public ShortcutTest()
  {
    InitializeComponent();
  }

  private void timer1_Tick(object sender, EventArgs e)
  {
    timer1.Enabled = false;

    keybd_event((byte)Keys.ControlKey, 0, 0, 0);

    // this would work: keybd_event((byte)Keys.X, 0, 0, 0);

    // this won't work
    SendChar('x');

    //keybd_event((byte)Keys.X, 0, KEYEVENTF_KEYUP, 0);

    keybd_event((byte)Keys.ControlKey, 0, KEYEVENTF_KEYUP, 0);

    button1.Enabled = true;
  }

  private void button1_Click(object sender, EventArgs e)
  {
    timer1.Enabled = true;
    button1.Enabled = false;
  }

  public void SendChar(char ch)
  {
    uint[] input = new uint[] { (uint)ch };

    uint[] downStates = { KEY_STATE_DOWN | KEY_SHIFT_ANY_CONTROL };
    uint[] upStates = { KEY_SHIFT_NO_CHARACTER | KEY_SHIFT_ANY_CONTROL };

    PostKeybdMessage(HWND_FOREGROUND, 0, downStates[0], 1, downStates, input);

    // tested with KeyShiftDeadFlag and some others, with \0 char ...
    PostKeybdMessage(HWND_FOREGROUND, 0, upStates[0], 1, upStates, input);
  }

}

Edit: I just looked up the OpenNETCF implementation of SendKeys and they use keybd_event only (so “+a” will fail for example).

Answer 1

Have you tried using SendInput? I am actually using c++, and following code:

INPUT input[4];
memset(input, 0, sizeof(INPUT)*4);
input[0].type = INPUT_KEYBOARD;
input[0].ki.wVk = VK_MENU;

input[1].type = INPUT_KEYBOARD;
input[1].ki.wVk = L'a';

input[2].type = INPUT_KEYBOARD;
input[2].ki.wVk = VK_MENU;
input[2].ki.dwFlags = KEYEVENTF_KEYUP;

input[3].type = INPUT_KEYBOARD;
input[3].ki.wVk = L'a';
input[3].ki.dwFlags = KEYEVENTF_KEYUP;

SendInput(4, input, sizeof(INPUT));

generates messages that look like should work, I checked in spy on WM6.5.