Add new UI logic for ScanFormWidget, which is mainly about button enable and disable in different mode.

src/ScanFormWidget.h

@@ -6,15 +6,19 @@
 #define GUI_SCANFORMWIDGET_H
 
 #include "tabformwidget.h"
+#include <functional>
 class PatientInformationForm;
 class ScanFormWidget :public TabFormWidget {
         Q_OBJECT
 public:
-        explicit ScanFormWidget(QWidget *parent = nullptr);
-        ~ScanFormWidget();
-
+    explicit ScanFormWidget(QWidget *parent = nullptr);
+    ~ScanFormWidget();
+    void setPreviewing(bool val);
 private:
     PatientInformationForm* pat_inf= nullptr;
+    bool unset = true;
+    bool previewing= false;
+    std::function<void(bool)> previewfunc = nullptr;
 private slots:
     void protocolChanged(int type);