Question

I’m using the Windows API SendInput() call to simulate keyboard events. The following snippet (irrelevant details omitted) works perfectly for sending a sequence of characters:

wchar_t txt = ...; INPUT *input = ...; size_t nInput = 0;  for (unsigned int j = 0; j < length; j++) {     input[nInput].ki.wVk = 0;     input[nInput].ki.wScan = txt[j];     input[nInput].ki.dwFlags = KEYEVENTF_UNICODE;     nInput++;     input[nInput].ki.wVk = 0;     input[nInput].ki.wScan = txt[j];     input[nInput].ki.dwFlags = KEYEVENTF_UNICODE | KEYEVENTF_KEYUP;     nInput++; } SendInput(nInput, input, sizeoF(INPUT)); 

Now I’m trying to send single keypresses, with modifiers. I tried the following code:

bool control, alt shift; wchar_t chr;  if (control) {     input[nInput].ki.wVk = VK_CONTROL;     input[nInput].ki.dwFlags = 0;     nInput++; } if (alt) {     input[nInput].ki.wVk = VK_MENU;     input[nInput].ki.dwFlags = 0;     nInput++; } if (shift) {     input[nInput].ki.wVk = VK_SHIFT;     input[nInput].ki.dwFlags = 0;     nInput++; }  input[nInput].ki.wVk = 0; input[nInput].ki.wScan = chr; input[nInput].ki.dwFlags = KEYEVENTF_UNICODE; nInput++; input[nInput].ki.wVk = 0; input[nInput].ki.wScan = chr; input[nInput].ki.dwFlags = KEYEVENTF_UNICODE | KEYEVENTF_KEYUP; nInput++;  if (shift) {     input[nInput].ki.wVk = VK_SHIFT;     input[nInput].ki.dwFlags = KEYEVENTF_KEYUP;     nInput++; } if (alt) {     input[nInput].ki.wVk = VK_MENU;     input[nInput].ki.dwFlags = KEYEVENTF_KEYUP;     nInput++; } if (control) {     input[nInput].ki.wVk = VK_CONTROL;     input[nInput].ki.dwFlags = KEYEVENTF_KEYUP;     nInput++; } SendInput(nInput, input, sizeof(INPUT)); 

However, modifiers don’t seem to get through, i.e., even though, say control is set to true, the event sequence is received as a plain keypress.

Answer 1

Pax’s answer did not work out, but it lead me to the correct solution. In short: do not use KEYEVENTF_UNICODE for individual keypresses, rather, convert the character to a virtual key code, and send it that way. Here’s the relevant code:

SHORT virtKey = VkKeyScan((TCHAR) chr); input[nInput].ki.wVk = LOBYTE(virtKey); input[nInput].ki.dwFlags = 0; nInput++; input[nInput].ki.wVk = LOBYTE(virtKey); input[nInput].ki.dwFlags = KEYEVENTF_KEYUP; nInput++; 

I have not tested how this works for non-ASCII unicode characters, that are mapped to non-English keyboard layouts, and what happens when the layout set for my app is different from the layout set for the application in the front.