Fixed LMMS crash when pressing Q in not existing piano roll. (LMMS#3609)

src/gui/editors/PianoRoll.cpp

@@ -805,7 +805,7 @@ void PianoRoll::setBackgroundShade( const QColor & c )
 
 
 
-void PianoRoll::drawNoteRect( QPainter & p, int x, int y, 
+void PianoRoll::drawNoteRect( QPainter & p, int x, int y,
 				int width, const Note * n, const QColor & noteCol,
 				const QColor & selCol, const int noteOpc, const bool borders )
 {
@@ -1918,7 +1918,7 @@ void PianoRoll::mouseReleaseEvent( QMouseEvent * me )
 		{
 			// select the notes within the selection rectangle and
 			// then destroy the selection rectangle
-			computeSelectedNotes( 
+			computeSelectedNotes(
 					me->modifiers() & Qt::ShiftModifier );
 		}
 		else if( m_action == ActionMoveNote )
@@ -2463,15 +2463,15 @@ void PianoRoll::dragNotes( int x, int y, bool alt, bool shift, bool ctrl )
 				}
 			}
 		}
-	} 
+	}
 	else if (m_action == ActionResizeNote)
 	{
 		// When resizing notes:
 		// If shift is not pressed, resize the selected notes but do not rearrange them
 		// If shift is pressed we resize and rearrange only the selected notes
 		// If shift + ctrl then we also rearrange all posterior notes (sticky)
 		// If shift is pressed but only one note is selected, apply sticky
-			
+
 		if (shift)
 		{
 			// Algorithm:
@@ -2491,8 +2491,8 @@ void PianoRoll::dragNotes( int x, int y, bool alt, bool shift, bool ctrl )
 			const Note *posteriorNote = nullptr;
 			for (const Note *note : notes)
 			{
-				if (note->selected() && (posteriorNote == nullptr || 
-					note->oldPos().getTicks() + note->oldLength().getTicks() > 
+				if (note->selected() && (posteriorNote == nullptr ||
+					note->oldPos().getTicks() + note->oldLength().getTicks() >
 					posteriorNote->oldPos().getTicks() + posteriorNote->oldLength().getTicks()))
 				{
 					posteriorNote = note;
@@ -2512,9 +2512,9 @@ void PianoRoll::dragNotes( int x, int y, bool alt, bool shift, bool ctrl )
 				if(note->selected())
 				{
 					// scale relative start and end positions by scaleFactor
-					int newStart = stretchStartTick + scaleFactor * 
+					int newStart = stretchStartTick + scaleFactor *
 						(note->oldPos().getTicks() - stretchStartTick);
-					int newEnd = stretchStartTick + scaleFactor * 
+					int newEnd = stretchStartTick + scaleFactor *
 						(note->oldPos().getTicks()+note->oldLength().getTicks() - stretchStartTick);
 					// if  not holding alt, quantize the offsets
 					if(!alt)
@@ -2533,7 +2533,7 @@ void PianoRoll::dragNotes( int x, int y, bool alt, bool shift, bool ctrl )
 					int newLength = qMax(1, newEnd-newStart);
 					if (note == posteriorNote)
 					{
-						posteriorDeltaThisFrame = (newStart+newLength) - 
+						posteriorDeltaThisFrame = (newStart+newLength) -
 							(note->pos().getTicks() + note->length().getTicks());
 					}
 					note->setLength( MidiTime(newLength) );
@@ -3918,27 +3918,32 @@ int PianoRoll::quantization() const
 
 void PianoRoll::quantizeNotes()
 {
+	if( ! hasValidPattern() )
+	{
+		return;
+	}
+
 	NoteVector notes = getSelectedNotes();
 
-	if (notes.empty())
+	if( notes.empty() )
 	{
-		for (Note* n : m_pattern->notes())
+		for( Note* n : m_pattern->notes() )
 		{
-			notes.push_back(n);
+			notes.push_back( n );
 		}
 	}
 
-	for (Note* n : notes)
+	for( Note* n : notes )
 	{
-		if (n->length() == MidiTime(0))
+		if( n->length() == MidiTime( 0 ) )
 		{
 			continue;
 		}
 
 		Note copy(*n);
-		m_pattern->removeNote(n);
-		copy.quantizePos(quantization());
-		m_pattern->addNote(copy);
+		m_pattern->removeNote( n );
+		copy.quantizePos( quantization() );
+		m_pattern->addNote( copy );
 	}
 
 	update();