Fix #6107 : bar lines and brackets disappearing when some of the staf…

…f they span is hidden

Fixed by analyzing brackets and bar line spans rather than only relying on start and stop staff Y offset (which is not set if the staff is not shown).

Note: there are still issues with measure numbers, but these belong more to system items than to bar lining.

libmscore/barline.cpp

@@ -133,16 +133,43 @@ void BarLine::getY(qreal* y1, qreal* y2) const
                   measure = system->firstMeasure();
                   }
             if (measure) {
+                  // test start and end staff visibility
+                  int   span = _span;
+                  Staff* staff1 = score()->staff(staffIdx1);
+                  Staff* staff2 = score()->staff(staffIdx2);
+                  SysStaff* sysStaff1 = system->staff(staffIdx1);
+                  SysStaff* sysStaff2 = system->staff(staffIdx2);
+                  while (span > 0) {
+                        // if start staff not shown, reduce span and move one staff down
+                        if ( !(sysStaff1->show() && staff1->show()) ) {
+                              span--;
+                              sysStaff1 = system->staff(++staffIdx1);
+                              staff1    = score()->staff(staffIdx1);
+                        }
+                        // if end staff not shown, reduce span and move one staff up
+                        else if ( !(sysStaff2->show() && staff2->show()) ) {
+                              span--;
+                              sysStaff2 = system->staff(--staffIdx2);
+                              staff2    = score()->staff(staffIdx2);
+                        }
+                        // if both staves shown, exit loop
+                        else
+                              break;
+                  }
+                  // if no longer any span, set 0 length and exit
+                  if (span <= 0) {
+                        *y1 = *y2 = 0;
+                        return;
+                  }
+                  // both staffIdx1 and staffIdx2 are shown: compute corresponding line length
                   StaffLines* l1 = measure->staffLines(staffIdx1);
                   StaffLines* l2 = measure->staffLines(staffIdx2);
 
                   if (system)
-                        yp += system->staff(staffIdx1)->y();
+                        yp += sysStaff1->y();
                   *y1 = l1->y1() - yp;
-                  Staff* staff1 = score()->staff(staffIdx1);
                   *y1 += (_spanFrom * staff1->lineDistance() * staff1->spatium()) / 2;
                   *y2 = l2->y1() - yp;
-                  Staff* staff2 = score()->staff(staffIdx2);
                   *y2 += (_spanTo   * staff2->lineDistance() * staff2->spatium()) / 2;
                   }
             }
@@ -201,11 +228,14 @@ void BarLine::drawDots(QPainter* painter, qreal x) const
 
 void BarLine::draw(QPainter* painter) const
       {
-      qreal _spatium = score()->spatium();
-
-      qreal lw = score()->styleS(ST_barWidth).val() * _spatium;
+      // get line length and do nothing if 0 (or near enough)
       qreal y1, y2;
       getY(&y1, &y2);
+      if (y2-y1 < 0.1)
+            return;
+
+      qreal _spatium = score()->spatium();
+      qreal lw = score()->styleS(ST_barWidth).val() * _spatium;
 
       QPen pen(curColor(), lw, Qt::SolidLine, Qt::FlatCap);
       painter->setPen(pen);

libmscore/measure.cpp

@@ -2273,17 +2273,38 @@ void Measure::scanElements(void* data, void (*func)(void*, Element*), bool all)
 
       int tracks = nstaves * VOICES;
       for (Segment* s = first(); s; s = s->next()) {
-            for (int track = 0; track < tracks; ++track) {
-                  int staffIdx = track/VOICES;
-                  if (!all && !(visible(staffIdx) && score()->staff(staffIdx)->show())) {
-                        track += VOICES - 1;
-                        continue;
+            // bar line visibility depends on spanned staves,
+            // not simply on visibility of first staff
+            if (s->segmentType() == Segment::SegBarLine || s->segmentType() == Segment::SegEndBarLine
+                  || Segment::SegStartRepeatBarLine) {
+                  for (int staffIdx = 0; staffIdx < nstaves; ++staffIdx) {
+                        Element* e = s->element(staffIdx*VOICES);
+                        if (e == 0)             // if no element, skip
+                              continue;
+                        // if staff not visible
+                        if (!all && !(visible(staffIdx) && score()->staff(staffIdx)->show())) {
+                              // if bar line spans just this staff...
+                              if (static_cast<BarLine*>(e)->span() <= 1
+                                    // ...or span another staff but without entering INTO it...
+                                    || (static_cast<BarLine*>(e)->span() < 2 &&
+                                          static_cast<BarLine*>(e)->spanTo() < 1) )
+                              continue;         // ...skip
+                              }
+                        e->scanElements(data, func, all);
                         }
-                  Element* e = s->element(track);
-                  if (e == 0)
-                        continue;
-                  e->scanElements(data, func, all);
                   }
+            else
+                  for (int track = 0; track < tracks; ++track) {
+                        int staffIdx = track/VOICES;
+                        if (!all && !(visible(staffIdx) && score()->staff(staffIdx)->show())) {
+                              track += VOICES - 1;
+                              continue;
+                              }
+                        Element* e = s->element(track);
+                        if (e == 0)
+                              continue;
+                        e->scanElements(data, func, all);
+                        }
             foreach(Element* e, s->annotations()) {
                   if (all || e->systemFlag() || visible(e->staffIdx()))
                         e->scanElements(data,  func, all);

libmscore/system.cpp

@@ -390,8 +390,20 @@ void System::layout2()
       n = _brackets.size();
       for (int i = 0; i < n; ++i) {
             Bracket* b = _brackets.at(i);
-            qreal sy = _staves[b->firstStaff()]->bbox().top();
-            qreal ey = _staves[b->lastStaff()]->bbox().bottom();
+            int staffIdx1 = b->firstStaff();
+            int staffIdx2 = b->lastStaff();
+            qreal sy = 0;                       // assume bracket not visible
+            qreal ey = 0;
+            // if start staff not visible, try next staff
+            while (!_staves[staffIdx1]->show() && staffIdx1 < staffIdx2)
+                  ++staffIdx1;
+            // if end staff not visible, try prev staff
+            while (!_staves[staffIdx2]->show() && staffIdx1 < staffIdx2)
+                  --staffIdx2;
+            if (staffIdx1 < staffIdx2) {        // if at least two staves visible for this bracket
+                  sy = _staves[staffIdx1]->bbox().top();
+                  ey = _staves[staffIdx2]->bbox().bottom();
+                  }
             b->rypos() = sy;
             b->setHeight(ey - sy);
             b->layout();