Screen Painter

/*****************************************************************************************
 *									  ScreenPainter_DLL.cpp                                   *		
 *****************************************************************************************
 *	AUTHOR      : Bahrudin Hrnjica                                                               *
 *	PROJECT     : ScreenPainter_DLL 																 *
 *	DESCRIPTION :  ScreenPainter_DLL.cpp : Defines the entry point for the DLL application.   *
 *					Hook system Keyboard Event,WH_KEYBOARD,Application will Un/Install   *
 *					this Hook DLL.If user click on a key,Post a user-defined msg to apps *
 *  -----------------------------------------------------------------------------------  *
 *	Revision History :                                                                   *
 *  08/05/2003  Bahrudin.    Initial Version.                                                *
 *	                                                                                     *
 *  -----------------------------------------------------------------------------------  *
 *								Copyright (c) 2003                       *
 ****************************************************************************************/

//PCH Header
#include "stdafx.h"

//Handle of windows which will recieve the Key Nook
HWND hWndReceiver = NULL;

//Global variables used for handling the keyboard hook
static UINT UWM_KEYDOWN; //Message ID
HHOOK hookKeyBoard;		 //Hook ID
HINSTANCE hInst;		 //Instance od the dll

//Function declaration
static LRESULT CALLBACK KeyboardHook(UINT nCode, WPARAM wParam, LPARAM lParam);
__declspec(dllexport) BOOL InstallKBHook(HWND hWnd);
__declspec(dllexport) BOOL UnInstallKBHook(HWND hWnd);


//Dll main entry function
BOOL APIENTRY DllMain( HINSTANCE  hInstance,DWORD  ul_reason_for_call,LPVOID lpReserved)
{
	switch(ul_reason_for_call)
	{
	case DLL_PROCESS_ATTACH:
		UWM_KEYDOWN = ::RegisterWindowMessage("UWM_KEYDOWN_MSG-0A63-49c3-9ACB-CF0068027A66");
		hInst = hInstance;
		return TRUE;
	case DLL_PROCESS_DETACH:
		return TRUE;
	}
    return TRUE;
}

// if user click on Keyboard, PostMsg to Apps
 
/*****************************************************************************************
 *	FUNCTION    : KeyboardHook(UINT nCode, WPARAM wParam, LPARAM lParam)                 *
 *---------------------------------------------------------------------------------------*
 *	DESCRIPTION : If the user clicks on Keyboard, Post message to the Application        *
 *	                                                                                     *
 *	ARGUMENT    : nCode  : Message code, depends on message                              *
 *	              wParam  : Additional Parameters                                        *
 *	              lParam  : Additional Parameter                                         *
 *	                                                                                     *
 *	RETURN      : Result of Hooking the message                                          *
 ****************************************************************************************/
static LRESULT CALLBACK KeyboardHook(UINT nCode, WPARAM wParam, LPARAM lParam)
{
	

	if( (nCode >=0) && (nCode == HC_ACTION) && (wParam == VK_ESCAPE))	
		::PostMessage(hWndReceiver,UWM_KEYDOWN,wParam,0);

	/*if( (nCode >=0) && (nCode == HC_ACTION) && (wParam == VK_RETURN))	
		::PostMessage(hWndReceiver,UWM_KEYDOWN,wParam,0);*/

	if( (nCode >=0) && (nCode == HC_ACTION) && (wParam == 'C' ||wParam == 'c' ))
		::PostMessage(hWndReceiver,UWM_KEYDOWN,wParam,0);
		
	
	if( (nCode >=0) && (nCode == HC_ACTION) && (wParam == 'W' ||wParam == 'w' ))	
		::PostMessage(hWndReceiver,UWM_KEYDOWN,wParam,0);
	if( (nCode >=0) && (nCode == HC_ACTION) && (wParam == 'X' ||wParam == 'x' ))	
		::PostMessage(hWndReceiver,UWM_KEYDOWN,wParam,0);
	if( (nCode >=0) && (nCode == HC_ACTION) && (wParam == 'q' ||wParam == 'Q' ))	
		::PostMessage(hWndReceiver,UWM_KEYDOWN,wParam,0);

	if( (nCode >=0) && (nCode == HC_ACTION) && (wParam == 'r' ||wParam == 'R' ))	
		::PostMessage(hWndReceiver,UWM_KEYDOWN,wParam,0);
	if( (nCode >=0) && (nCode == HC_ACTION) && (wParam == 'g' ||wParam == 'G' ))	
		::PostMessage(hWndReceiver,UWM_KEYDOWN,wParam,0);
	if( (nCode >=0) && (nCode == HC_ACTION) && (wParam == 'b' ||wParam == 'B' ))	
		::PostMessage(hWndReceiver,UWM_KEYDOWN,wParam,0);
	if( (nCode >=0) && (nCode == HC_ACTION) && (wParam == 'y' ||wParam == 'Y' ))	
		::PostMessage(hWndReceiver,UWM_KEYDOWN,wParam,0);

	if( (nCode >=0) && (nCode == HC_ACTION))
		::PostMessage(hWndReceiver,UWM_KEYDOWN,wParam,0);

	return CallNextHookEx(hookKeyBoard,nCode,wParam,lParam);
}
 
/*****************************************************************************************
 *	FUNCTION    : InstallKBHook(HWND hWnd)                                               *
 *---------------------------------------------------------------------------------------*
 *	DESCRIPTION : Main application will call this method to Hook keyboard, must "EXPORT  *
 *	                                                                                     *
 *	                                                                                     *
 *	ARGUMENT    : hWnd  : Handler of Windows which has to recieve the hook               *
 *	                                                                                     *
 *	RETURN      : True if Successful                                                     *
 ****************************************************************************************/
__declspec(dllexport) BOOL InstallKBHook(HWND hWnd)
{
	if( hWndReceiver != NULL) //If the reciever recieve the hook
		return FALSE; //reHook

	hookKeyBoard = SetWindowsHookEx(WH_KEYBOARD,(HOOKPROC)KeyboardHook,	hInst,0);
	//If hookKeyboard instaled corectly
	if(hookKeyBoard != NULL)
	{ 
		hWndReceiver  = hWnd;
		return TRUE;
	}
	return FALSE;
} 




/*****************************************************************************************
 *	FUNCTION    : __declspec(dllexport) BOOL UnInstallKBHook(HWND hWnd)                  *
 *---------------------------------------------------------------------------------------*
 *	DESCRIPTION : Main application will call this method to UnHook keyboard              *
 *	                                                                                     *
 *	ARGUMENT    : hWnd  : Handler of Windows which has to recieve the hook               *
 *	RETURN      : True if successfull                                                    *
 ****************************************************************************************/
__declspec(dllexport) BOOL UnInstallKBHook(HWND hWnd)
{
	if((hWnd == NULL) || (hWnd != hWndReceiver))
		return FALSE;
    BOOL bUnHook = UnhookWindowsHookEx(hookKeyBoard);
	if(bUnHook)
		 hWndReceiver = NULL;

    return bUnHook;
}