解决双张保留后如果有无纸等错误状态，一直正在扫描未退出线程

sane/scanner.cpp

@@ -489,7 +489,7 @@ scanner::scanner(SCANNERID id) : handle_(NULL), id_(id), ex_id_(EXTENSION_ID_BAS
 								, dpi_(200), tmp_path_(L""), img_ind_(0)
 								, scanner_name_(L""), cfg_(NULL), is_ui_wait_img_(false), is_scanning_(false)
 								, scanner_ev_handler_(NULL), evh_param_(NULL), app_wnd_(NULL), user_cancel_(false)
-								, max_img_mem_(400), wait_fetch_(60 * 1000), twain_set_(false), ev_cnt_(0), is_bIndicator(false), is_show_setting_(false)
+								, max_img_mem_(400), wait_fetch_(60 * 1000), twain_set_(false), ev_cnt_(0), is_bIndicator(false), is_show_setting_(false), is_in_working_thread_(false)
 {
 	ui_notify = std::function<void(int, void*, int)>();
 
@@ -1602,6 +1602,7 @@ int scanner::set_is_multiout(bool enable)
 
 int scanner::thread_start(void)
 {
+	is_in_working_thread_ = false;
 	scan_over_ = false;
 	double_handle_ = DOUBLE_FEED_NEED_UI;
 
@@ -1632,7 +1633,7 @@ int scanner::thread_start(void)
 		// 
 		err_ = ret;
 #ifdef START_SCAN_IN_THREAD
-		if (callback::show_progress_ui && is_bIndicator && ui_notify)
+		if (callback::show_progress_ui && is_bIndicator && ui_notify && !is_in_working_thread_)
 		{
 			int ev = SANE_EVENT_WORKING;
 		
@@ -1669,7 +1670,41 @@ int scanner::thread_start(void)
 
 int scanner::thread_start_after_keep()
 {
+	is_in_working_thread_ = false;
+
 	int ret = hg_sane_middleware::instance()->start(handle_, NULL);
+
+	if (ret != SANE_STATUS_GOOD && ret != SCANNER_ERR_DEVICE_DOUBLE_FEEDING)
+	{
+		if (callback::show_progress_ui && is_bIndicator && ui_notify)
+		{
+			int ev = ret;
+
+			if (!is_in_working_thread_)
+				ui_notify(SANE_EVENT_SCAN_FINISHED, (void*)hg_scanner_err_description(ret), ret);
+		}
+		else
+		{
+			scan_over_ = true;
+			if (callback::close_ui)
+				callback::close_ui(UI_INDICATOR);
+
+			if (callback::show_messagebox_ui)
+			{
+				callback::show_messagebox_ui(app_wnd_, ret, (void*)hg_scanner_err_description(ret), 0);
+			}
+			else
+			{
+				std::wstring	msg(local_trans::a2u(hg_scanner_err_description(ret), CP_UTF8));
+				if (!IsWindow(app_wnd_))
+					callback::bring_message_box_topmost(local_trans::lang_trans_between_hz936(CONST_STRING_START_FAILED).c_str());
+				MessageBoxW(app_wnd_, msg.c_str(), local_trans::lang_trans_between_hz936(CONST_STRING_START_FAILED).c_str(), MB_OK | MB_ICONERROR);
+			}
+			is_scanning_ = false;
+		}
+	}
+
+	
 	return ret;
 }
 
@@ -3610,6 +3645,7 @@ int scanner::handle_device_event(int ev_code, void* data, unsigned int* len)
 	dlg_indicator* prog = indicator_;
 	if (ev_code == SANE_EVENT_WORKING)
 	{
+		is_in_working_thread_ = true;
 		img_ind_ = 0;
 		if (prog)
 			prog->notify_working();
@@ -3710,6 +3746,7 @@ int scanner::handle_device_event(int ev_code, void* data, unsigned int* len)
 		}
 		else
 		{
+			is_in_working_thread_ = false;
 			err_ = *len;
 			scan_over_ = true;
 			scan_msg_ = data ? (char*)data : "OK";

sane/scanner.h

@@ -86,6 +86,7 @@ class scanner : public ISaneInvoker, virtual public refer
 	void*	evh_param_;
 	HWND	app_wnd_;		// for MessageBox
 	bool	is_show_ui_;
+	bool	is_in_working_thread_;
 
 	int transfer_id(int id);	// transfer fixed SANE option ID to real id, -1 is none
 	void transport_config_file(void);