stop from UI in a new thread

twain/ds/scanner.cpp

@@ -264,6 +264,9 @@ scanner::~scanner()
 	if (thread_starting_.get() && thread_starting_->joinable())
 		thread_starting_->join();
 	thread_starting_.reset();
+	if (thread_stop_.get() && thread_stop_->joinable())
+		thread_stop_->join();
+	thread_stop_.reset();
 }
 
 void scanner::get_scanner_name(const char* model, std::vector<std::string>& names)
@@ -398,7 +401,11 @@ void scanner::on_ui_event(int uev, void* sender)
 	{
 		// scan cancelled 
 
-		stop();	// nothing to do, the finishing work do in SANE_EVENT_SCAN_FINISHED
+		if (thread_stop_.get() && thread_stop_->joinable())
+			thread_stop_->join();
+		thread_stop_.reset(new std::thread(&scanner::stop, this));
+		return;		// notify in SCAN_FINISHED
+		//stop();	// nothing to do, the finishing work do in SANE_EVENT_SCAN_FINISHED
 	}
 	else if (uev == SANE_EVENT_SCAN_FINISHED)
 	{
@@ -824,19 +831,20 @@ int scanner::thread_start(void)
 				ui_notify(SANE_EVENT_SCAN_FINISHED, (void*)sane_helper_->invoke_sane_strstatus((SANE_Status)ret), ret);
 
 				// block ?
-				while (!is_scanning_)
-				{
-#ifdef WIN32
-					MSG	msg = { 0 };
-					PeekMessageW(&msg, NULL, 0, 0, PM_NOREMOVE);
-#else
-					std::this_thread::sleep_for(std::chrono::milliseconds(3));
-#endif
-				}
+//				while (!is_scanning_)
+//				{
+//#ifdef WIN32
+//					MSG	msg = { 0 };
+//					PeekMessageW(&msg, NULL, 0, 0, PM_NOREMOVE);
+//#else
+//					std::this_thread::sleep_for(std::chrono::milliseconds(3));
+//#endif
+//				}
 			}
 		}
-		else
+		else 
 #endif
+		if (!scan_working_)
 		{
 			if (callback::close_ui)
 				callback::close_ui(UI_INDICATOR);

twain/ds/scanner.h

@@ -78,7 +78,8 @@ class scanner : public ISaneInvoker, virtual public refer
 
 	int thread_start(void);
 	std::unique_ptr<std::thread>	thread_starting_;
-	bool							scan_working_ = false;
+	std::unique_ptr<std::thread>	thread_stop_;			// stop阻塞到工作线程结束，在结束回调后才返回。为不阻塞界面，在线程中停止
+	bool							scan_working_ = false;	// start阻塞到有一张图片才返回，如果第一张出现错误（比如卡纸），则回调先于start返回结束标志。该变量用于协调FINISH事件通知
 
 
 	template<class T>