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bool scanner::perform_scan_twain(std::vector<std::string>& files)
{
	typedef TwainObject(FAR PASCAL createTwainObject)(LPCSTR, LPCSTR);
	typedef VOID(FAR PASCAL deleteTwainObject)(TwainObject);
	typedef HRESULT(FAR PASCAL initTwain)(TwainObject);
	typedef HRESULT(FAR PASCAL setProc)(TwainObject, pGetData , DWORD_PTR );
	typedef HRESULT(FAR PASCAL selectSourceGUI)(TwainObject);
	typedef HRESULT(FAR PASCAL openSource)(TwainObject);
	typedef HRESULT(FAR PASCAL enableSource)(TwainObject, HWND, BOOL);

	const raii_loadlibrary libraryloader("xcscan40.dll", "xcscan40.dll");
	auto lib_inst = libraryloader.get_hinstance();

	auto fn_createTwainObject = (createTwainObject FAR*)GetProcAddress(lib_inst, "SXC_CreateTwainObject");
	auto fn_deleteTwainObject = (deleteTwainObject FAR*)GetProcAddress(lib_inst, "SXC_DeleteTwainObject");
	auto fn_initTwain = (initTwain FAR*)GetProcAddress(lib_inst, "SXC_InitTwain");
	auto fn_setProc = (setProc FAR*)GetProcAddress(lib_inst, "SXC_SetProc");
	auto fn_selectSourceGUI = (selectSourceGUI FAR*)GetProcAddress(lib_inst, "SXC_SelectSourceGUI");
	auto fn_openSource = (openSource FAR*)GetProcAddress(lib_inst, "SXC_OpenSource");
	auto fn_enableSource = (enableSource FAR*)GetProcAddress(lib_inst, "SXC_EnableSource");

	TwainObject twain_obj = fn_createTwainObject("<private>", "<private>");
	if (!twain_obj)
		throw std::exception("Unable to create TWAIN object.");

	// Ensure the twain_obj is deleted when we exit scope.
	auto cleanup_twain = gsl::finally([&twain_obj, &fn_deleteTwainObject]() {fn_deleteTwainObject(twain_obj); });

	HRESULT hr = fn_initTwain(twain_obj);

	if (IS_DS_FAILED(hr))
		throw std::exception("Unable to initialise TWAIN.");
	
	if (IS_DS_FAILED(fn_setProc(twain_obj, [](DWORD_PTR u, const BYTE* b, DWORD s) { return reinterpret_cast<scanner*>(u)->get_data_callback(b, s); }, reinterpret_cast<DWORD_PTR>(this))))
		throw std::exception("Failed to set data-retrieval procedure.");

	if (IS_DS_FAILED(fn_selectSourceGUI(twain_obj)))
		throw std::exception("Unable to select source GUI.");

	if (IS_DS_FAILED(fn_openSource(twain_obj)))
		throw std::exception("Unable to open source.");

	if (IS_DS_FAILED(fn_enableSource(twain_obj, wxo_win_mainhwnd, true)))
		throw std::exception("Unable to enable source.");

	return true;
}