display message if project is empty and user tries to export it (closes #2091056)

git-svn-id: https://lmms.svn.sf.net/svnroot/lmms/trunk/lmms@1571 0778d3d1-df1d-0410-868b-ea421aaaa00d

src/core/song.cpp

@@ -1110,6 +1110,16 @@ void song::restoreControllerStates( const QDomElement & _this )
 
 void song::exportProject( void )
 {
+	if( isEmpty() )
+	{
+		QMessageBox::information( engine::getMainWindow(),
+				tr( "Empty project" ),
+				tr( "This project is empty so exporting makes "
+					"no sense. Please put some items into "
+					"Song Editor first!" ) );
+		return;
+	}
+
 	QString base_filename;
 
 	if( m_fileName != "" )

src/core/track_container.cpp

@@ -130,6 +130,24 @@ void trackContainer::loadSettings( const QDomElement & _this )
 
 
 
+int trackContainer::countTracks( track::TrackTypes _tt ) const
+{
+	int cnt = 0;
+	m_tracksMutex.lockForRead();
+	for( int i = 0; i < m_tracks.size(); ++i )
+	{
+		if( m_tracks[i]->type() == _tt || _tt == track::NumTrackTypes )
+		{
+			++cnt;
+		}
+	}
+	m_tracksMutex.unlock();
+	return( cnt );
+}
+
+
+
+
 void trackContainer::addTrack( track * _track )
 {
 	if( _track->type() != track::HiddenAutomationTrack )
@@ -163,7 +181,6 @@ void trackContainer::removeTrack( track * _track )
 
 
 
-
 void trackContainer::updateAfterTrackAdd( void )
 {
 }
@@ -171,7 +188,6 @@ void trackContainer::updateAfterTrackAdd( void )
 
 
 
-
 void trackContainer::clearAllTracks( void )
 {
 	//m_tracksMutex.lockForWrite();
@@ -185,19 +201,17 @@ void trackContainer::clearAllTracks( void )
 
 
 
-int trackContainer::countTracks( track::TrackTypes _tt ) const
+bool trackContainer::isEmpty( void ) const
 {
-	int cnt = 0;
-	m_tracksMutex.lockForRead();
-	for( int i = 0; i < m_tracks.size(); ++i )
+	for( trackList::const_iterator it = m_tracks.begin();
+						it != m_tracks.end(); ++it )
 	{
-		if( m_tracks[i]->type() == _tt || _tt == track::NumTrackTypes )
+		if( !( *it )->getTCOs().isEmpty() )
 		{
-			++cnt;
+			return false;
 		}
 	}
-	m_tracksMutex.unlock();
-	return( cnt );
+	return true;
 }
 
 

src/gui/main_window.cpp

@@ -531,7 +531,7 @@ bool mainWindow::mayChangeProject( void )
 		return( TRUE );
 	}
 
-	QMessageBox mb ( tr( "Project not saved" ),
+	QMessageBox mb( tr( "Project not saved" ),
 				tr( "The current project was modified since "
 					"last saving. Do you want to save it "
 								"now?" ),