fix #295703: Slurs to grace notes disappear after inserting bars

Resolves: https://musescore.org/en/node/295703. When the SPANNER_TICK property of a spanner changes, the spanner's startElement and endElement are invalidated. Usually the spanner's start and end elements can be recalculated from the SPANNER_TICK and SPANNER_TICKS properties, but since grace notes occur on the same tick as their parent notes, determining the real start and elements for grace note slurs is tricky. The solution here is to invalidate the start and end elements in an undoable manner before changing the SPANNER_TICK property of the spanner when time is added or removed before the spanner's start, and then set the start and end elements back to what they were. This required modifying Score::undoChangeSpannerElements() so that the start and end elements can be changed to or from nullptr.
musescore · Oct 29, 2019 · a37fda3 · a37fda3
1 parent ff43723
commit a37fda3
Showing 1 changed file with 29 additions and 17 deletions.
diff --git a/libmscore/edit.cpp b/libmscore/edit.cpp
@@ -4861,8 +4861,8 @@ void Score::undoChangeSpannerElements(Spanner* spanner, Element* startElement, E
       {
       Element* oldStartElement = spanner->startElement();
       Element* oldEndElement = spanner->endElement();
-      int startDeltaTrack = startElement->track() - oldStartElement->track();
-      int endDeltaTrack = endElement->track() - oldEndElement->track();
+      int startDeltaTrack = startElement && oldStartElement ? startElement->track() - oldStartElement->track() : 0;
+      int endDeltaTrack = endElement && oldEndElement ? endElement->track() - oldEndElement->track() : 0;
       // scan all spanners linked to this one
       for (ScoreElement* el : spanner->linkList()) {
             Spanner* sp = toSpanner(el);
@@ -4871,24 +4871,28 @@ void Score::undoChangeSpannerElements(Spanner* spanner, Element* startElement, E
             // if not the current spanner, but one linked to it, determine its new start and end elements
             // as modifications 'parallel' to the modifications of the current spanner's start and end elements
             if (sp != spanner) {
-                  // determine the track where to expect the 'parallel' start element
-                  int newTrack = sp->startElement()->track() + startDeltaTrack;
-                  // look in elements linked to new start element for an element with
-                  // same score as linked spanner and appropriate track
-                  for (ScoreElement* ee : startElement->linkList()) {
-                        Element* e = toElement(ee);
-                        if (e->score() == sp->score() && e->track() == newTrack) {
-                              newStartElement = e;
-                              break;
+                  if (startElement) {
+                        // determine the track where to expect the 'parallel' start element
+                        int newTrack = sp->startElement() ? sp->startElement()->track() + startDeltaTrack : 0;
+                        // look in elements linked to new start element for an element with
+                        // same score as linked spanner and appropriate track
+                        for (ScoreElement* ee : startElement->linkList()) {
+                              Element* e = toElement(ee);
+                              if (e->score() == sp->score() && e->track() == newTrack) {
+                                    newStartElement = e;
+                                    break;
+                                    }
                               }
                         }
                   // similarly to determine the 'parallel' end element
-                  newTrack = sp->endElement()->track() + endDeltaTrack;
-                  for (ScoreElement* ee : endElement->linkList()) {
-                        Element* e = toNote(ee);
-                        if (e->score() == sp->score() && e->track() == newTrack) {
-                              newEndElement = e;
-                              break;
+                  if (endElement) {
+                        int newTrack = sp->endElement() ? sp->endElement()->track() + endDeltaTrack : 0;
+                        for (ScoreElement* ee : endElement->linkList()) {
+                              Element* e = toElement(ee);
+                              if (e->score() == sp->score() && e->track() == newTrack) {
+                                    newEndElement = e;
+                                    break;
+                                    }
                               }
                         }
                   }
@@ -5008,7 +5012,11 @@ void Score::undoInsertTime(const Fraction& tick, const Fraction& len)
                         // and
                         //            +----spanner--------
                         //  +---add---+
+                        Element* startElement = s->startElement();
+                        Element* endElement = s->endElement();
+                        undoChangeSpannerElements(s, nullptr, nullptr);
                         s->undoChangeProperty(Pid::SPANNER_TICK, s->tick() + len);
+                        undoChangeSpannerElements(s, startElement, endElement);
                         }
                   }
             else {
@@ -5021,7 +5029,11 @@ void Score::undoInsertTime(const Fraction& tick, const Fraction& len)
                         Fraction t = s->tick() + len;
                         if (t < Fraction(0,1))
                               t = Fraction(0,1);
+                        Element* startElement = s->startElement();
+                        Element* endElement = s->endElement();
+                        undoChangeSpannerElements(s, nullptr, nullptr);
                         s->undoChangeProperty(Pid::SPANNER_TICK, t);
+                        undoChangeSpannerElements(s, startElement, endElement);
                         }
                   else if (s->tick() >= tick && s->tick2() <= tick2) {
                         //