caps-min.c

/*
	CapsLang by Ryurik 2003-11-12, updated 2006-10-24

	This small windowless program allow you swich keyboard layout with CapsLock key.
	While non-standard keyboard layout will bright Scroll Lock indicator

	Installation: copy capslang.exe to your Startup (Start -> Programs) folder.
	Run: Just run capslang.exe and enjoy
	Exit: To close programm press Ctrl + Alt + L
	Note: Does not work with Win9x!

	Эта программа позволяет переключать раскладку клавиатуры кнопкой CapsLock.
	Для обычного использования CapsLock следует нажать Shift+CapsLock.
	Рекомендуется установить в Windows отключение режима CapsLock клавишей Shift
	При использовании альтернативной раскладки загорается индикатор ScrollLock.
	Для выхода из программы следует нажать Ctrl + Alt + L.
	Программа предназначена для работы в операционных системах Windows 2000/XP.
 */

#define _WIN32_WINNT 0x500

#include <windows.h>
#include <tchar.h>

#define WH_KEYBOARD_LL     13
typedef struct tagKBDLLHOOKSTRUCT {
    DWORD   vkCode;
    DWORD   scanCode;
    DWORD   flags;
    DWORD   time;
    DWORD   dwExtraInfo;
} KBDLLHOOKSTRUCT, FAR *LPKBDLLHOOKSTRUCT, *PKBDLLHOOKSTRUCT;

#define EXIT 33

HKL		caps_default;
HHOOK	caps_khook;
HANDLE  caps_hEvent;
//UINT	caps_key = VK_RCONTROL;
UINT	caps_key = VK_CAPITAL;
#define INPUTLANGCHANGE_FORWARD 2

HWND GetCaretWindow()
{
//	HWND Active = GetActiveWindow();
	HWND Active = GetForegroundWindow();
/*
	DWORD ThreadId = GetWindowThreadProcessId(Active, NULL);
	GUITHREADINFO ThreadInfo;
	ThreadInfo.cbSize = sizeof(GUITHREADINFO);
	GetGUIThreadInfo(ThreadId, &ThreadInfo);

	return ThreadInfo.hwndFocus;
*/
	return Active;
}

LRESULT CALLBACK KbdHook(int nCode,WPARAM wParam,LPARAM lParam) {
	if (nCode<0)	return CallNextHookEx(caps_khook,nCode,wParam,lParam);
	if (nCode==HC_ACTION) {
		KBDLLHOOKSTRUCT *ks=(KBDLLHOOKSTRUCT*)lParam;
		if (ks->vkCode==caps_key && (GetKeyState(VK_SHIFT)>=0)) {
			if (wParam==WM_KEYDOWN) {
				HWND hWnd=GetCaretWindow();
				if (hWnd) {
					PostMessage(hWnd,WM_INPUTLANGCHANGEREQUEST,0,(LPARAM)HKL_NEXT);
//					PostMessage(hWnd,WM_INPUTLANGCHANGEREQUEST,(WPARAM)INPUTLANGCHANGE_FORWARD,0);
//					PostMessage(hWnd,WM_INPUTLANGCHANGEREQUEST,(WPARAM)INPUTLANGCHANGE_FORWARD,(LPARAM)HKL_NEXT);
					return TRUE;
				}
			}
		}
	}
skip:
	return CallNextHookEx(caps_khook,nCode,wParam,lParam);
}

void  failedx(const TCHAR *msg) {
	MessageBox(NULL,msg,_T("CapsLang - Error"),MB_OK|MB_ICONERROR);
	ExitProcess(1);
}

void  failed(const TCHAR *msg) {
	DWORD	fm;
	TCHAR	*msg1,*msg2;
	const TCHAR	*args[2];

	fm=FormatMessage(FORMAT_MESSAGE_ALLOCATE_BUFFER|FORMAT_MESSAGE_FROM_SYSTEM|
 FORMAT_MESSAGE_IGNORE_INSERTS,NULL,GetLastError(),0,(LPTSTR)&msg1,0,NULL);
	if (fm==0)
		ExitProcess(1);
	args[0]=msg;
	args[1]=msg1;
	fm=FormatMessage(FORMAT_MESSAGE_ALLOCATE_BUFFER|FORMAT_MESSAGE_FROM_STRING|
 FORMAT_MESSAGE_ARGUMENT_ARRAY,_T("%1: %2"),0,0,(LPTSTR)&msg2,0,(va_list*)&args[0]);
	if (fm==0)
		ExitProcess(1);
	MessageBox(NULL,msg2,_T("Capslang Exception"),MB_OK|MB_ICONERROR);
	ExitProcess(1);
}

int APIENTRY WinMain(HINSTANCE hInst, HINSTANCE hInstPrev, LPSTR cmd, int show) {
	MSG		msg;

	caps_hEvent=CreateEvent(NULL,TRUE,FALSE,_T("CapsLang"));
	if (caps_hEvent==NULL)
		failed(_T("CreateEvent()"));
	if (GetLastError()==ERROR_ALREADY_EXISTS) {
		failedx(_T("CapsLang is already running!"));
		goto quit;
	}

	caps_default = GetKeyboardLayout(0);
	if (RegisterHotKey(0,EXIT,MOD_CONTROL|MOD_ALT,'L')==0)
		failed(_T("RegisterHotKey()"));

	caps_khook=SetWindowsHookEx(WH_KEYBOARD_LL,KbdHook,GetModuleHandle(0),0);
	if (caps_khook==0)
		failed(_T("SetWindowsHookEx()"));

	while (GetMessage(&msg,0,0,0)) {
		TranslateMessage(&msg);
		if(msg.message==WM_HOTKEY && msg.wParam==EXIT) PostQuitMessage(0);
		DispatchMessage(&msg);
	}

	UnhookWindowsHookEx(caps_khook);
	CloseHandle(caps_hEvent);
quit:
	ExitProcess(0);
	return 0;
}