Add higher abstraction funcs for sending keystrokes, add const parms

The original functions had the API details of sending keys absolutely
correct, but they were cumbersome to use due to not abstracting away the
press and release aspect and manual creation of INPUT structs.

The manual management of objects also saved a few operations, but with
the frequency that these functions are called it's probably better to
have more abstract code than preventing a 28 byte object from being stack
copied twice every 2 seconds or so.

src/tabcontrollers/keyboardinput/KeyboardInputWindows.cpp

@@ -4,6 +4,17 @@
 
 namespace advsettings
 {
+/*!
+Represents the state of a keyboard button press. Can be either Up or Down.
+
+Implemented because neither Qt nor Windows.h included a sensible key state enum.
+*/
+enum class KeyStatus
+{
+    Up,
+    Down,
+};
+
 void fillKiStruct( INPUT& ip, WORD scanCode, bool keyup )
 {
     ip.type = INPUT_KEYBOARD;
@@ -21,11 +32,12 @@ void fillKiStruct( INPUT& ip, WORD scanCode, bool keyup )
     ip.ki.time = 0;
 };
 
-void sendKeyboardInputRaw( int inputCount, LPINPUT input )
+void sendKeyboardInputRaw( const int inputCount, const LPINPUT input )
 {
-    if ( ( inputCount > 0 )
-         && !SendInput(
-                static_cast<UINT>( inputCount ), input, sizeof( INPUT ) ) )
+    const auto success
+        = SendInput( static_cast<UINT>( inputCount ), input, sizeof( INPUT ) );
+
+    if ( ( inputCount > 0 ) && !success )
     {
         char* err;
         auto errCode = GetLastError();
@@ -50,6 +62,62 @@ void sendKeyboardInputRaw( int inputCount, LPINPUT input )
     }
 }
 
+/*!
+Returns an INPUT struct with the corresponding virtualKeyCode and keyStatus set.
+
+All fields except ki.wVk and ki.dwFlags are zero.
+The INPUT struct is used with the SendInput Windows function.
+Official Docs:
+https://docs.microsoft.com/en-us/windows/desktop/api/winuser/ns-winuser-taginput
+*/
+INPUT createInputStruct( const WORD virtualKeyCode, const KeyStatus keyStatus )
+{
+    // Zero init to ensure random data doesn't muck something up.
+    INPUT input = {};
+
+    input.type = INPUT_KEYBOARD;
+
+    input.ki.wVk = virtualKeyCode;
+
+    if ( keyStatus == KeyStatus::Up )
+    {
+        input.ki.dwFlags = KEYEVENTF_KEYUP;
+    }
+    else if ( keyStatus == KeyStatus::Down )
+    {
+        // Struct is already zero initialized, but this is here for clarity.
+        // Compiler will likely sort this out, otherwise the performance hit is
+        // negligible.
+        // There is no corresponding KEYDOWN event, you just don't
+        // set KEYEVENTF_KEYUP.
+        input.ki.dwFlags = 0;
+    }
+
+    // The sizeof(INPUT) on MSVC is 28. Returning by value is a non-issue
+    // compared to the simplicity of not having to pass a ref to an already
+    // existing INPUT struct, and possibly forgetting to zero it out.
+    return input;
+}
+
+/*!
+Sends a key press to Windows. The virtualKeyCode is a Windows specific define
+found in <windows.h>.
+
+Virtual Key Codes offical docs:
+https://docs.microsoft.com/en-us/windows/desktop/inputdev/virtual-key-codes
+*/
+void sendKeyPressAndRelease( const WORD virtualKeyCode )
+{
+    const auto press = createInputStruct( virtualKeyCode, KeyStatus::Down );
+    const auto release = createInputStruct( virtualKeyCode, KeyStatus::Up );
+
+    constexpr auto numberOfActions = 2;
+
+    INPUT actions[numberOfActions] = { press, release };
+
+    sendKeyboardInputRaw( numberOfActions, actions );
+}
+
 void KeyboardInputWindows::sendKeyboardInput( QString input )
 {
     int len = input.length();