fix: Popup a message when there is no data to export

DSView/pv/data/decoderstack.cpp

@@ -69,6 +69,7 @@ DecoderStack::DecoderStack(pv::SigSession *session,
     _snapshot = NULL;
     _progress = 0;
     _is_decoding = false;
+    _result_count = 0;
     
     _stack.push_back(new decode::Decoder(dec));
  
@@ -375,6 +376,7 @@ void DecoderStack::init()
     _error_message = QString();
     _no_memory = false;
     _snapshot = NULL;
+    _result_count = 0;
 
     for (auto i = _rows.begin();i != _rows.end(); i++) { 
         (*i).second->clear();
@@ -802,6 +804,7 @@ void DecoderStack::annotation_callback(srd_proto_data *pdata, void *self)
         d->_no_memory = true;
         return;     
     }
+    d->_result_count++;
 
 	// Find the row
 	assert(pdata->pdo);

DSView/pv/data/decoderstack.h

@@ -183,6 +183,10 @@ public:
 
     bool check_required_probes();
 
+    inline uint64_t get_result_count(){
+        return _result_count;
+    }
+
 private:
     void decode_data(const uint64_t decode_start, const uint64_t decode_end, srd_session *const session);
 	void execute_decode_stack();
@@ -218,6 +222,7 @@ private:
     bool            _is_capture_end;
     int             _progress;
     bool            _is_decoding;
+    uint64_t        _result_count;
 
 	friend class DecoderStackTest::TwoDecoderStack;
 };

DSView/pv/dialogs/protocolexp.cpp

@@ -43,6 +43,7 @@
 #include "../utility/path.h"
 #include "../log.h"
 #include "../ui/langresource.h"
+#include "../ui/msgbox.h"
 
 #define EXPORT_DEC_ROW_COUNT_MAX 20
 
@@ -108,7 +109,14 @@ ProtocolExp::ProtocolExp(QWidget *parent, SigSession *session) :
 }
 
 void ProtocolExp::accept()
-{ 
+{   
+    if (_session->have_decoded_result() == false)
+    {
+        QString errMsg = L_S(STR_PAGE_MSG, S_ID(IDS_MSG_NO_DECODED_RESULT), "No data to export");
+        MsgBox::Show(errMsg);
+        return;
+    }
+
     QDialog::accept();
 
     if (_row_sel_list.empty()){

DSView/pv/sigsession.cpp

@@ -2556,4 +2556,15 @@ namespace pv
         }
     }
 
+    bool SigSession::have_decoded_result()
+    {
+        for (auto trace : _decode_traces){
+            if (trace->decoder()->get_result_count() > 0){
+                return true;
+            }
+        }
+
+        return false;
+    }
+
 } // namespace pv

DSView/pv/sigsession.h

@@ -449,6 +449,8 @@ public:
 
     void update_lang_text();
 
+    bool have_decoded_result();
+
 private:
     void set_cur_samplelimits(uint64_t samplelimits);
     void set_cur_snap_samplerate(uint64_t samplerate);