Automating Windows Applications

// NotepadPlugin.cpp : Defines the entry point for the DLL application.
//

#include "stdafx.h"

// Import type library for IHandlerPtr
#include "ImportNotepadHandlerTlb.h"

// File contains functions to find/wait for window of specified class 
#include "GetTargetAppWindow.cpp"

static IHandlerPtr g_spHandler = NULL; // pointer to embedded COM object

static const UINT WM_CREATE_OBJECT = RegisterWindowMessage( _T("Create Object") );

static DWORD g_pfnOldFrameWndProc;	// pointer to original frame window procedure
static DWORD g_pfnOldViewWndProc;   // pointer to original view  window procedure


//
// New frame window procedure
//
LRESULT CALLBACK FrameWndProc(HWND hWnd, UINT dwMsg, WPARAM wParam, LPARAM lParam) 
{
	if ( WM_CREATE_OBJECT == dwMsg )
	{
		// Handler of special message to create embedded COM object
		if ( FAILED(CoInitialize(NULL)) )
		{
			// If COM initialization failed then restore original window procedure
			SetWindowLong( hWnd, GWL_WNDPROC, (DWORD)g_pfnOldFrameWndProc );
			return 0;
		}

		HRESULT hr = E_FAIL;
		if ( NULL == g_spHandler )
			// Create embedded COM object
			hr = g_spHandler.CreateInstance( __uuidof(Handler) );

		if ( SUCCEEDED(hr) )
			// Provide embedded COM object with Notepad frame window handle
			hr = g_spHandler->SetWnd( (DWORD)hWnd );

		if ( SUCCEEDED(hr) )
			// Register embedded COM object with Running Objects Table (ROT)
			hr = g_spHandler->RegisterWithROT();

		if ( SUCCEEDED(hr) )
			//MessageBox( hWnd, _T("I've been Automated!"), _T("Notepad"), MB_TOPMOST );
			SetWindowText( hWnd, _T("Notepad  [Automated]") );	

		return hr;
	}
	
	switch ( dwMsg )
	{
	case WM_DESTROY:
		if ( NULL != g_spHandler )
		{
			g_spHandler->UnregisterWithROT();
			g_spHandler = NULL;
			MessageBox( hWnd, _T("Bye-Bye..."), _T("Notepad"), MB_TOPMOST );
		}
		break;
	}

	// Pass message on to the original window procedure
	return CallWindowProc( (WNDPROC)g_pfnOldFrameWndProc, hWnd, dwMsg, wParam, lParam );
}


//
// New view window procedure
//
LRESULT CALLBACK ViewWndProc(HWND hWnd, UINT dwMsg, WPARAM wParam, LPARAM lParam) 
{
	switch ( dwMsg )
	{
	case WM_CHAR:
		// Key pressed, char inserted to view window
		if ( g_spHandler )
		{
			TCHAR szChar[2];
			_stprintf( szChar, _T("%c"), (TCHAR)wParam );

			// Pass inserted character to embedded COM object
			g_spHandler->SetText( (_bstr_t)szChar );
		}
		break;
	}

	// Pass message on to the original window procedure
	return CallWindowProc( (WNDPROC)g_pfnOldViewWndProc, hWnd, dwMsg, wParam, lParam );
}


//
// Injected DLL activities function
//
BOOL PluginProc()
{
	BOOL br = FALSE;

	// Find/wait for window of specified class
	HWND hWnd = WaitForWndOfClass( g_szTargetWndClass );
	if ( 0 != hWnd )
	{
		// Subclass frame window of target application
		g_pfnOldFrameWndProc = GetWindowLong( hWnd, GWL_WNDPROC );
		SetWindowLong( hWnd, GWL_WNDPROC, (DWORD)FrameWndProc );

		// Subclass view window
		HWND hClientWnd = GetWindow( hWnd, GW_CHILD );
		g_pfnOldViewWndProc = GetWindowLong( hClientWnd, GWL_WNDPROC );
		SetWindowLong( hClientWnd, GWL_WNDPROC, (DWORD)ViewWndProc );

		// Post message to new window procedure to create COM object
		PostMessage( hWnd, WM_CREATE_OBJECT, 0, 0 );
		br = TRUE;
	}

	return br;
}

	
//
// Dll entry point
//
BOOL WINAPI DllMain(HINSTANCE hInstance, DWORD nReason, LPVOID pReserved)
{
	BOOL br = FALSE;
	if ( nReason == DLL_PROCESS_ATTACH )
		br = PluginProc();

	return br;
}