//=============================================================================
//  MuseScore
//  Music Composition & Notation
//
//  Copyright (C) 2002-2016 Werner Schweer
//
//  This program is free software; you can redistribute it and/or modify
//  it under the terms of the GNU General Public License version 2
//  as published by the Free Software Foundation and appearing in
//  the file LICENCE.GPL
//=============================================================================

#include "measure.h"
#include "score.h"
#include "system.h"
#include "undo.h"
#include "chord.h"
#include "stem.h"
#include "slur.h"
#include "tie.h"
#include "part.h"
#include "navigate.h"
#include "articulation.h"

namespace Ms {

Element* SlurTie::editEndElement;
Element* SlurTie::editStartElement;
QList<SlurOffsets> SlurTie::editUps;

//---------------------------------------------------------
//   draw
//---------------------------------------------------------

void SlurSegment::draw(QPainter* painter) const
      {
      QPen pen(curColor());
      switch (slurTie()->lineType()) {
            case 0:
                  painter->setBrush(QBrush(pen.color()));
                  pen.setCapStyle(Qt::RoundCap);
                  pen.setJoinStyle(Qt::RoundJoin);
                  pen.setWidthF(score()->styleP(StyleIdx::SlurEndWidth));
                  break;
            case 1:
                  painter->setBrush(Qt::NoBrush);
                  pen.setWidthF(score()->styleP(StyleIdx::SlurDottedWidth));
                  pen.setStyle(Qt::DotLine);
                  break;
            case 2:
                  painter->setBrush(Qt::NoBrush);
                  pen.setWidthF(score()->styleP(StyleIdx::SlurDottedWidth));
                  pen.setStyle(Qt::DashLine);
                  break;
            case 3:
                  painter->setBrush(Qt::NoBrush);
                  pen.setWidthF(score()->styleP(StyleIdx::SlurDottedWidth));
                  pen.setStyle(Qt::CustomDashLine);
                  QVector<qreal> dashes { 5.0, 5.0 };
                  pen.setDashPattern(dashes);
                  break;
            }
      painter->setPen(pen);
      painter->drawPath(path);
      }

//---------------------------------------------------------
//   startEdit
//---------------------------------------------------------

void SlurSegment::startEdit(EditData& ed)
      {
      ed.grips   = int(Grip::GRIPS);
      ed.curGrip = Grip::END;
      }

//---------------------------------------------------------
//   updateGrips
//    return grip rectangles in page coordinates
//---------------------------------------------------------

void SlurSegment::updateGrips(EditData& ed) const
      {
      QPointF p(pagePos());
      for (int i = 0; i < ed.grips; ++i)
            ed.grip[i].translate(_ups[i].p + _ups[i].off + p);
      }

//---------------------------------------------------------
//   searchCR
//---------------------------------------------------------

static ChordRest* searchCR(Segment* segment, int startTrack, int endTrack)
      {
      // for (Segment* s = segment; s; s = s->next1MM(SegmentType::ChordRest)) {
      for (Segment* s = segment; s; s = s->next(SegmentType::ChordRest)) {     // restrict search to measure
            if (startTrack > endTrack) {
                  for (int t = startTrack-1; t >= endTrack; --t) {
                        if (s->element(t))
                              return toChordRest(s->element(t));
                        }
                  }
            else {
                  for (int t = startTrack; t < endTrack; ++t) {
                        if (s->element(t))
                              return toChordRest(s->element(t));
                        }
                  }
            }
      return 0;
      }

//---------------------------------------------------------
//   edit
//    return true if event is accepted
//---------------------------------------------------------

bool SlurSegment::edit(EditData& ed)
      {
      Slur* sl = slur();

      if (ed.key == Qt::Key_X) {
            sl->setSlurDirection(sl->up() ? Direction::DOWN : Direction::UP);
            sl->layout();
            return true;
            }
      if (ed.key == Qt::Key_Home) {
            ups(ed.curGrip).off = QPointF();
            sl->layout();
            return true;
            }

      if (!((ed.modifiers & Qt::ShiftModifier) && (isSingleType() || (isBeginType() && ed.curGrip == Grip::START) || (isEndType() && ed.curGrip == Grip::END))))
            return false;

      ChordRest* cr = 0;
      ChordRest* e;
      ChordRest* e1;
      if (ed.curGrip == Grip::START) {
            e = sl->startCR();
            e1 = sl->endCR();
            }
      else {
            e = sl->endCR();
            e1 = sl->startCR();
            }

      if (ed.key == Qt::Key_Left)
            cr = prevChordRest(e);
      else if (ed.key == Qt::Key_Right)
            cr = nextChordRest(e);
      else if (ed.key == Qt::Key_Up) {
            Part* part     = e->part();
            int startTrack = part->startTrack();
            int endTrack   = e->track();
            cr = searchCR(e->segment(), endTrack, startTrack);
            }
      else if (ed.key == Qt::Key_Down) {
            int startTrack = e->track() + 1;
            Part* part     = e->part();
            int endTrack   = part->endTrack();
            cr = searchCR(e->segment(), startTrack, endTrack);
            }
      if (cr && cr != e1)
            changeAnchor(ed.view, ed.curGrip, cr);
      return true;
      }

//---------------------------------------------------------
//   changeAnchor
//---------------------------------------------------------

void SlurSegment::changeAnchor(MuseScoreView* viewer, Grip curGrip, Element* element)
      {
      if (curGrip == Grip::START) {
            spanner()->setStartElement(element);
            switch (spanner()->anchor()) {
                  case Spanner::Anchor::NOTE: {
                        Tie* tie = toTie(spanner());
                        Note* note = toNote(element);
                        if (note->chord()->tick() <= tie->endNote()->tick()) {
                              tie->startNote()->setTieFor(0);
                              tie->setStartNote(note);
                              note->setTieFor(tie);
                              }
                        break;
                        }
                  case Spanner::Anchor::CHORD:
                        spanner()->setTick(element->tick());
                        spanner()->setTick2(spanner()->endElement()->tick());
                        spanner()->setTrack(element->track());
                        if (score()->spannerMap().removeSpanner(spanner()))
                              score()->addSpanner(spanner());
                        break;
                  case Spanner::Anchor::SEGMENT:
                  case Spanner::Anchor::MEASURE:
                        qDebug("SlurSegment::changeAnchor: bad anchor");
                        break;
                  }
            }
      else {
            spanner()->setEndElement(element);
            switch (spanner()->anchor()) {
                  case Spanner::Anchor::NOTE: {
                        Tie* tie = toTie(spanner());
                        Note* note = toNote(element);
                        // do not allow backward ties
                        if (note->chord()->tick() >= tie->startNote()->tick()) {
                              tie->endNote()->setTieBack(0);
                              tie->setEndNote(note);
                              note->setTieBack(tie);
                              }
                        break;
                        }
                  case Spanner::Anchor::CHORD:
                        spanner()->setTick2(element->tick());
                        spanner()->setTrack2(element->track());
                        break;

                  case Spanner::Anchor::SEGMENT:
                  case Spanner::Anchor::MEASURE:
                        qDebug("SlurSegment::changeAnchor: bad anchor");
                        break;
                  }
            }

      int segments  = spanner()->spannerSegments().size();
      ups(curGrip).off = QPointF();
      spanner()->layout();
      if (spanner()->spannerSegments().size() != segments) {
            QList<SpannerSegment*>& ss = spanner()->spannerSegments();

            SlurSegment* newSegment = toSlurSegment(curGrip == Grip::END ? ss.back() : ss.front());
//            score()->endCmd();
//            score()->startCmd();
            viewer->startEdit(newSegment, curGrip);
//            score()->setLayoutAll();
            triggerLayout();
            }
      }

//---------------------------------------------------------
//   gripAnchor
//---------------------------------------------------------

QPointF SlurSegment::gripAnchor(Grip grip) const
      {
      SlurPos spos;
      slurTie()->slurPos(&spos);

      QPointF pp(pagePos());
      QPointF p1(ups(Grip::START).p + pp);
      QPointF p2(ups(Grip::END).p + pp);

      switch (spannerSegmentType()) {
            case SpannerSegmentType::SINGLE:
                  if (grip == Grip::START)
                        return p1;
                  else if (grip == Grip::END)
                        return p2;
                  break;

            case SpannerSegmentType::BEGIN:
                  if (grip == Grip::START)
                        return p1;
                  else if (grip == Grip::END)
                        return system()->abbox().topRight();
                  break;

            case SpannerSegmentType::MIDDLE:
                  if (grip == Grip::START)
                        return system()->pagePos();
                  else if (grip == Grip::END)
                        return system()->abbox().topRight();
                  break;

            case SpannerSegmentType::END:
                  if (grip == Grip::START)
                        return system()->pagePos();
                  else if (grip == Grip::END)
                        return p2;
                  break;
            }
      return QPointF();
      }

//---------------------------------------------------------
//   editDrag
//---------------------------------------------------------

void SlurSegment::editDrag(EditData& ed)
      {
      Grip g = ed.curGrip;
      ups(g).off += ed.delta;

      if (g == Grip::START || g == Grip::END) {
            computeBezier();
            //
            // move anchor for slurs/ties
            //
            if ((g == Grip::START && isSingleBeginType()) || (g == Grip::END && isSingleEndType())) {
                  Spanner* spanner = slurTie();
                  Qt::KeyboardModifiers km = qApp->keyboardModifiers();
                  Note* note = static_cast<Note*>(ed.view->elementNear(ed.pos));
                  if (note && note->isNote()
                     && ((g == Grip::END && note->tick() > slurTie()->tick()) || (g == Grip::START && note->tick() < slurTie()->tick2()))
                     ) {
                        if (km != (Qt::ShiftModifier | Qt::ControlModifier)) {
                              Chord* c = note->chord();
                              ed.view->setDropTarget(note);
                              if (c != spanner->endCR()) {
                                    changeAnchor(ed.view, g, c);
                                    }
                              }
                        }
                  else
                        ed.view->setDropTarget(0);
                  }
            }
      else if (ed.curGrip == Grip::BEZIER1 || ed.curGrip == Grip::BEZIER2) {
            computeBezier();
            }
      else if (ed.curGrip == Grip::SHOULDER) {
            ups(ed.curGrip).off = QPointF();
            computeBezier(ed.delta);
            }
      else if (ed.curGrip == Grip::DRAG) {
            ups(Grip::DRAG).off = QPointF();
            setUserOff(userOff() + ed.delta);
            }
      undoChangeProperty(P_ID::AUTOPLACE, false);
      }

//---------------------------------------------------------
//   computeBezier
//    compute help points of slur bezier segment
//---------------------------------------------------------

void SlurSegment::computeBezier(QPointF p6o)
      {
      qreal _spatium  = spatium();
      qreal shoulderW;              // height as fraction of slur-length
      qreal shoulderH;
      //
      // p1 and p2 are the end points of the slur
      //
      QPointF pp1 = ups(Grip::START).p + ups(Grip::START).off;
      QPointF pp2 = ups(Grip::END).p   + ups(Grip::END).off;

      QPointF p2 = pp2 - pp1;
      if ((p2.x() == 0.0) && (p2.y() == 0.0)) {
            Measure* m1 = slur()->startCR()->segment()->measure();
            Measure* m2 = slur()->endCR()->segment()->measure();
            qDebug("zero slur at tick %d(%d) track %d in measure %d-%d  tick %d ticks %d",
               m1->tick(), tick(), track(), m1->no(), m2->no(), slur()->tick(), slur()->ticks());
            slur()->setBroken(true);
            return;
            }

      qreal sinb = atan(p2.y() / p2.x());
      QTransform t;
      t.rotateRadians(-sinb);
      p2  = t.map(p2);
      p6o = t.map(p6o);

      double smallH = 0.5;
      qreal d = p2.x() / _spatium;
      if (d <= 2.0) {
            shoulderH = d * 0.5 * smallH * _spatium;
            shoulderW = .6;
            }
      else {
            qreal dd = log10(1.0 + (d - 2.0) * .5) * 2.0;
            if (dd > 3.0)
                  dd = 3.0;
            shoulderH = (dd + smallH) * _spatium;
            if (d > 18.0)
                  shoulderW = 0.7; // 0.8;
            else if (d > 10)
                  shoulderW = 0.6; // 0.7;
            else
                  shoulderW = 0.5; // 0.6;
            }

      shoulderH -= p6o.y();

      if (!slur()->up())
            shoulderH = -shoulderH;

      qreal c    = p2.x();
      qreal c1   = (c - c * shoulderW) * .5 + p6o.x();
      qreal c2   = c1 + c * shoulderW       + p6o.x();

      QPointF p5 = QPointF(c * .5, 0.0);

      QPointF p3(c1, -shoulderH);
      QPointF p4(c2, -shoulderH);

      qreal w = score()->styleP(StyleIdx::SlurMidWidth) - score()->styleP(StyleIdx::SlurEndWidth);
      if ((c2 - c1) <= _spatium)
            w *= .5;
      QPointF th(0.0, w);    // thickness of slur

      QPointF p3o = p6o + t.map(ups(Grip::BEZIER1).off);
      QPointF p4o = p6o + t.map(ups(Grip::BEZIER2).off);

      if (!p6o.isNull()) {
            QPointF p6i = t.inverted().map(p6o);
            ups(Grip::BEZIER1).off += p6i ;
            ups(Grip::BEZIER2).off += p6i;
            }

      //-----------------------------------calculate p6
      QPointF pp3  = p3 + p3o;
      QPointF pp4  = p4 + p4o;
      QPointF ppp4 = pp4 - pp3;

      qreal r2 = atan(ppp4.y() / ppp4.x());
      t.reset();
      t.rotateRadians(-r2);
      QPointF p6  = QPointF(t.map(ppp4).x() * .5, 0.0);

      t.rotateRadians(2 * r2);
      p6 = t.map(p6) + pp3 - p6o;
      //-----------------------------------

      path = QPainterPath();
      path.moveTo(QPointF());
      path.cubicTo(p3 + p3o - th, p4 + p4o - th, p2);
      if (slur()->lineType() == 0)
            path.cubicTo(p4 +p4o + th, p3 + p3o + th, QPointF());

      th = QPointF(0.0, 3.0 * w);
      shapePath = QPainterPath();
      shapePath.moveTo(QPointF());
      shapePath.cubicTo(p3 + p3o - th, p4 + p4o - th, p2);
      shapePath.cubicTo(p4 +p4o + th, p3 + p3o + th, QPointF());

      // translate back
      t.reset();
      t.translate(pp1.x(), pp1.y());
      t.rotateRadians(sinb);
      path                  = t.map(path);
      shapePath             = t.map(shapePath);
      ups(Grip::BEZIER1).p  = t.map(p3);
      ups(Grip::BEZIER2).p  = t.map(p4);
      ups(Grip::END).p      = t.map(p2) - ups(Grip::END).off;
      ups(Grip::DRAG).p     = t.map(p5);
      ups(Grip::SHOULDER).p = t.map(p6);

      QPainterPath p;
      p.moveTo(QPointF());
      p.cubicTo(p3 + p3o - th, p4 + p4o - th, p2);
      _shape.clear();
      QPointF start;
      start = t.map(start);
      int nbShapes = 15;
      for (int i = 1; i <= nbShapes; i++) {
            QPointF point = t.map(p.pointAtPercent(i/float(nbShapes)));
            QRectF re(start, point);
            _shape.add(re);
            start = point;
            }
      }

//---------------------------------------------------------
//   slurDistance
//---------------------------------------------------------

inline static qreal slurDistance(const Shape& shape, const QPointF& pt, qreal sdist, bool up)
      {
      qreal ddy;
      if (up) {
            ddy = -shape.bottomDistance(pt) + sdist;
            if (ddy <= 0.0)   // assume no more collisions
                  ddy = 0.0;
            }
      else {
            ddy = shape.topDistance(pt) - sdist;
            if (ddy >= 0.0)
                  ddy = 0.0;
            }
      return ddy;
      }

//---------------------------------------------------------
//   layoutSegment
//    p1, p2  are in System coordinates
//---------------------------------------------------------

void SlurSegment::layoutSegment(const QPointF& p1, const QPointF& p2)
      {
      if (autoplace()) {
            // TODO: must be saved when switching to autoplace
            for (UP& up : _ups)
                  up.off = QPointF();
            rUserYoffset() = 0;
            }
      ups(Grip::START).p = p1;
      ups(Grip::END).p   = p2;
      computeBezier();

      if (autoplace() && system()) {
            bool up = slur()->up();
            //
            // lookup segments for collision detection
            //
            struct Collision {
                  qreal dist;
                  QPointF p;
                  Collision(qreal a, const QPointF b) : dist(a), p(b) {}
                  };
            QList<Collision> pl;                // skyline
            qreal sdist = score()->styleP(StyleIdx::SlurMinDistance);

            QPointF pp1 = ups(Grip::START).p;
            QPointF pp2 = ups(Grip::END).p;
            Segment* ls = system()->lastMeasure()->last();
            Segment* fs = system()->firstMeasure()->first();

            for (Segment* s = fs; s && s != ls; s = s->next1()) {
                  if (!s->enabled())
                        continue;
                  qreal x1 = s->x() + s->measure()->x();
                  qreal x2 = x1 + s->width();
                  if (pp1.x() > x2)
                        continue;
                  if (pp2.x() >= x1 && pp2.x() < x2)
                        break;
                  if (up) {
                        QPointF pt = QPointF(s->x() + s->measure()->x(), s->staffShape(staffIdx()).top() + s->y() + s->measure()->y());
                        qreal dist = _shape.bottomDistance(pt) - sdist;
                        if (dist < 0.0)
                              pl.append(Collision(-dist, pt));
                        }
                  else {
                        QPointF pt = QPointF(s->x() + s->measure()->x(), s->staffShape(staffIdx()).bottom() + s->y() + s->measure()->y());
                        qreal dist = _shape.topDistance(pt) - sdist;
                        if (dist < 0.0)
                              pl.append(Collision(dist, pt));
                        }
                  }
            //
            // compute shape
            //    pl contains a list of colliding points
            //
#if 0  // does not work
            for (int i = 0; i < pl.size() - 1; ++i) {
                  Collision& c1 = pl[i];
                  Collision& c2 = pl[i+1];
                  if (qAbs(c1.p.y() - c2.p.y()) < 0.1) {
                        // combine the collisions
                        printf("  combine\n");
                        c1.p.rx() += (c2.p.x() - c1.p.x()) / 2.0;
                        pl.erase(pl.begin() + i + 1);
                        }
                  }
#endif
            if (!pl.empty()) {
//                  printf("%p collisions %d\n", this, pl.size());
                  qSort(pl.begin(), pl.end(), [](const Collision& a, const Collision& b) { return a.dist < b.dist; });
                  for (int i = 0; i < pl.size(); ++i) {
                        qreal ddy   = pl[i].dist;
                        qreal x     = pl[i].p.x();
                        qreal x1    = ups(Grip::BEZIER1).p.x();  // p1.x();
                        qreal x2    = ups(Grip::BEZIER2).p.x();  // p2.x();
                        qreal ratio = (x - x1) / (x2 - x1);

                        for (int k = 0; k < 30; ++k) {
                              const qreal magic = 1.1;
                              _ups[int(Grip::BEZIER1)].off.ry() -= ddy * magic * (1.0 - ratio);
                              _ups[int(Grip::BEZIER2)].off.ry() -= ddy * magic * ratio;
                              computeBezier();
                              qreal nddy = slurDistance(_shape, pl[i].p, sdist, up);
//                              printf("%d %d ddy %f  nddy %f  magic %f ratio %f\n", i, k, ddy, nddy, magic, ratio);
                              if (qAbs(nddy) <= spatium() * 0.1) {
//                                    printf("   collision %d  -- tries %d\n", i, k);
                                    break;
                                    }
                              ddy = nddy;
                              }

//                        ++i;
//                        if (i == pl.size())
//                              break;
//                        ddy = slurDistance(_shape, pl[i].p, sdist, up);
//                        printf("%p %f %f < %f\n", this, ddy, qAbs(ddy), minDistance);
//                        if (ddy < minDistance)
//                              break;
                        }
                  }
#if 0
            else {
                  // fallback: move whole slur
                  qreal ddy = up ? -1000000 : +1000000;
                  for (const Collision& c : pl)
                        ddy = up ? qMax(ddy, c.dist) : qMin(ddy, c.dist);
                  rUserYoffset() = -ddy;
                  }
#endif
            }
      else {
            if ((staffIdx() > 0) && score()->mscVersion() < 206 && !readPos().isNull()) {
                  QPointF staffOffset;
                  if (system() && track() >= 0)
                        staffOffset = QPointF(0.0, system()->staff(staffIdx())->y());
                  setReadPos(readPos() + staffOffset);
                  }
            adjustReadPos();
            }
      setbbox(path.boundingRect());
      }

//---------------------------------------------------------
//   isEdited
//---------------------------------------------------------

bool SlurSegment::isEdited() const
      {
      for (int i = 0; i < int(Grip::GRIPS); ++i) {
            if (!_ups[i].off.isNull())
                  return true;
            }
      return false;
      }

//---------------------------------------------------------
//   fixArticulations
//---------------------------------------------------------

static qreal fixArticulations(qreal yo, Chord* c, qreal _up)
      {
      //
      // handle special case of tenuto and staccato;
      //
      const QVector<Articulation*>& al = c->articulations();
      if (al.size() >= 2) {
            Articulation* a = al.at(1);
            if (a->up() == c->up())
                  return yo;
            else if (a->isTenuto() || a->isStaccato())
                  return a->y() + (a->height() + c->score()->spatium() * .3) * _up;
            }
      else if (al.size() >= 1) {
            Articulation* a = al.at(0);
            if (a->up() == c->up())
                  return yo;
            else if (a->isTenuto() || a->isStaccato())
                  return a->y() + (a->height() + c->score()->spatium() * .3) * _up;
            }
      return yo;
      }

//---------------------------------------------------------
//   slurPos
//    Calculate position of start- and endpoint of slur
//    relative to System() position.
//---------------------------------------------------------

void Slur::slurPosChord(SlurPos* sp)
      {
      Chord* stChord;
      Chord* enChord ;
      if (startChord()->isGraceAfter()){     // grace notes after, coming in reverse order
            stChord = endChord();
            enChord = startChord();
            _up = false;
            }
      else {
            stChord = startChord();
            enChord = endChord();
            }
      Note* _startNote = stChord->downNote();
      Note* _endNote   = enChord->downNote();
      qreal hw         = _startNote->headWidth();
      qreal __up       = _up ? -1.0 : 1.0;
      qreal _spatium = spatium();

      Measure* measure = endChord()->measure();
      sp->system1 = measure->system();
      if (!sp->system1) {             // DEBUG
            qDebug("no system1");
            return;
            }
      Q_ASSERT(sp->system1);
      sp->system2 = sp->system1;
      QPointF pp(sp->system1->pagePos());

      qreal xo;
      qreal yo;

      //------p1
      if (_up) {
            xo = _startNote->x() + hw * 1.12;
            yo = _startNote->pos().y() + hw * .3 * __up;
            }
      else {
            xo = _startNote->x() + hw * 0.4;
            yo = _startNote->pos().y() + _spatium * .75 * __up;
            }
      sp->p1 = stChord->pagePos() - pp + QPointF(xo, yo);

      //------p2
      if ((enChord->notes().size() > 1) || (enChord->stem() && !enChord->up() && !_up)) {
            xo = _endNote->x() - hw * 0.12;
            yo = _endNote->pos().y() + hw * .3 * __up;
            }
      else {
            xo = _endNote->x() + hw * 0.15;
            yo = _endNote->pos().y() + _spatium * .75 * __up;
            }
      sp->p2 = enChord->pagePos() - pp + QPointF(xo, yo);
      }

//---------------------------------------------------------
//   slurPos
//    calculate position of start- and endpoint of slur
//    relative to System() position
//---------------------------------------------------------

void Slur::slurPos(SlurPos* sp)
      {
      qreal _spatium = spatium();

      if (endCR() == 0) {
            sp->p1 = startCR()->pagePos();
            sp->p1.rx() += startCR()->width();
            sp->p2 = sp->p1;
            sp->p2.rx() += 5 * _spatium;
            sp->system1 = startCR()->measure()->system();
            sp->system2 = sp->system1;
            return;
            }

      bool useTablature  = staff() && staff()->isTabStaff(endCR()->tick());
      bool staffHasStems = true;     // assume staff uses stems
      StaffType*  stt    = 0;
      if (useTablature) {
            stt           = staff()->staffType(tick());
            staffHasStems = stt->stemThrough();   // if tab with stems beside, stems do not count for slur pos
            }

      // start and end cr, chord, and note
      ChordRest* scr = startCR();
      ChordRest* ecr = endCR();
      Chord* sc      = 0;
      Note* note1    = 0;
      if (scr->isChord()) {
            sc    = toChord(scr);
            note1 = _up ? sc->upNote() : sc->downNote();
            }
      Chord* ec = 0;
      Note* note2 = 0;
      if (ecr->isChord()) {
            ec   = toChord(ecr);
            note2 = _up ? ec->upNote() : ec->downNote();
            }

      sp->system1 = scr->measure()->system();
      sp->system2 = ecr->measure()->system();

      if (sp->system1 == 0) {
            qDebug("no system1");
            return;
            }

      sp->p1 = scr->pos() + scr->segment()->pos() + scr->measure()->pos();
      sp->p2 = ecr->pos() + ecr->segment()->pos() + ecr->measure()->pos();

      // account for centering or other adjustments (other than mirroring)
      if (note1 && !note1->mirror())
            sp->p1.rx() += note1->x();
      if (note2 && !note2->mirror())
            sp->p2.rx() += note2->x();

      qreal xo, yo;

      Stem* stem1 = sc && staffHasStems ? sc->stem() : 0;
      Stem* stem2 = ec && staffHasStems ? ec->stem() : 0;

      enum class SlurAnchor : char {
            NONE, STEM
            };
      SlurAnchor sa1 = SlurAnchor::NONE;
      SlurAnchor sa2 = SlurAnchor::NONE;
      // if slur is 'embedded' between either stem or both (as it might happen with voices)
      // link corresponding slur end to stem position
      if ((scr->up() == ecr->up()) && !scr->beam() && !ecr->beam() && (_up == scr->up())) {
            // both chords are facing same direction and slur is also in same direction
            // and no beams
            if (stem1)
                  sa1 = SlurAnchor::STEM;
            if (stem2)
                  sa2 = SlurAnchor::STEM;
            }

      qreal __up = _up ? -1.0 : 1.0;
      qreal hw1 = note1 ? note1->tabHeadWidth(stt) : scr->width();      // if stt == 0, tabHeadWidth()
      qreal hw2 = note2 ? note2->tabHeadWidth(stt) : ecr->width();      // defaults to headWidth()
      QPointF pt;
      switch (sa1) {
            case SlurAnchor::STEM:        //sc can't be null
                  // place slur starting point at stem base point
                  pt = sc->stemPos() - sc->pagePos() + sc->stem()->p2();
                  if (useTablature)                   // in tabs, stems are centred on note:
                        pt.rx() = hw1 * 0.5;          // skip half notehead to touch stem
                  sp->p1 += pt;
                  sp->p1 += QPointF(0.35 * _spatium, 0.25 * _spatium);  // clear the stem (x) and the notehead (y)
                  break;
            case SlurAnchor::NONE:
                  break;
            }
      switch (sa2) {
            case SlurAnchor::STEM:        //ec can't be null
                  pt = ec->stemPos() - ec->pagePos() + ec->stem()->p2();
                  if (useTablature)
                        pt.rx() = hw2 * 0.5;
                  sp->p2 += pt;
                  sp->p2 += QPointF(-0.35 * _spatium, 0.25 * _spatium);
                  break;
            case SlurAnchor::NONE:
                  break;
            }

      //
      // default position:
      //    horizontal: middle of notehead
      //    vertical:   _spatium * .4 above/below notehead
      //
      //------p1
      // Compute x0, y0 and stemPos
      if (sa1 == SlurAnchor::NONE || sa2 == SlurAnchor::NONE) { // need stemPos if sa2 == SlurAnchor::NONE
            bool stemPos = false;   // p1 starts at chord stem side

            // default positions
            xo = hw1 * .5;
            if (note1)
                  yo = note1->pos().y();
            else if (_up)
                  yo = scr->bbox().top();
            else
                  yo = scr->bbox().top() + scr->height();
            yo += _spatium * .9 * __up;

            // adjustments for stem and/or beam

            if (stem1) { //sc not null
                  Beam* beam1 = sc->beam();
                  if (beam1 && (beam1->elements().back() != sc) && (sc->up() == _up)) {
                        // start chord is beamed but not the last chord of beam group
                        // and slur direction is same as start chord (stem side)

                        // in these cases, layout start of slur to stem

                        qreal sh = stem1->height() + _spatium;
                        if (_up)
                              yo = sc->downNote()->pos().y() - sh;
                        else
                              yo = sc->upNote()->pos().y() + sh;
                        xo       = stem1->pos().x();

                        // force end of slur to layout to stem as well,
                        // if start and end chords have same stem direction
                        stemPos = true;
                        }
                  else {
                        // start chord is not beamed or is last chord of beam group
                        // or slur direction is opposite that of start chord

                        // at this point slur is in default position relative to note on slur side
                        // but we may need to make further adjustments

                        // if stem and slur are both up
                        // we need to clear stem horizontally
                        if (sc->up() && _up)
                              xo = hw1 + _spatium * .3;

                        //
                        // handle case: stem up   - stem down
                        //              stem down - stem up
                        //
                        if ((sc->up() != ecr->up()) && (sc->up() == _up)) {
                              // start and end chord have opposite direction
                              // and slur direction is same as start chord
                              // (so slur starts on stem side)

                              // float the start point along the stem to follow direction of movement
                              // see for example Gould p. 111

                              // get position of note on slur side for start & end chords
                              Note* n1  = sc->up() ? sc->upNote() : sc->downNote();
                              Note* n2  = 0;
                              if (ec)
                                    n2 = ec->up() ? ec->upNote() : ec->downNote();

                              // differential in note positions
                              qreal yd  = (n2 ? n2->pos().y() : ecr->pos().y()) - n1->pos().y();
                              yd *= .5;

                              // float along stem according to differential
                              qreal sh = stem1->height();
                              if (_up && yd < 0.0)
                                    yo = qMax(yo + yd, sc->downNote()->pos().y() - sh - _spatium);
                              else if (!_up && yd > 0.0)
                                    yo = qMin(yo + yd, sc->upNote()->pos().y() + sh + _spatium);

                              // we may wish to force end to align to stem as well,
                              // if it is in same direction
                              // (but it won't be, so this assignment should have no effect)
                              stemPos = true;
                              }
                        else if (sc->up() != _up) {
                              // slur opposite direction from chord
                              // avoid articulations
                              yo = fixArticulations(yo, sc, __up);
                              }
                        }
                  }
            else if (sc && sc->up() != _up) {
                  // slur opposite direction from chord
                  // avoid articulations
                  yo = fixArticulations(yo, sc, __up);
                  }

            if (sa1 == SlurAnchor::NONE)
                  sp->p1 += QPointF(xo, yo);

            //------p2
            if (sa2 == SlurAnchor::NONE) {

                  // default positions
                  xo = hw2 * .5;
                  if (note2)
                        yo = note2->pos().y();
                  else if (_up)
                        yo = endCR()->bbox().top();
                  else
                        yo = endCR()->bbox().top() + endCR()->height();
                  yo += _spatium * .9 * __up;

                  // adjustments for stem and/or beam

                  if (stem2) { //ec can't be null
                        Beam* beam2 = ec->beam();
                        if ((stemPos && (scr->up() == ec->up()))
                           || (beam2
                             && (!beam2->elements().empty())
                             && (beam2->elements().front() != ec)
                             && (ec->up() == _up)
                             && sc && (sc->noteType() == NoteType::NORMAL)
                             )
                              ) {

                              // slur start was laid out to stem and start and end have same direction
                              // OR
                              // end chord is beamed but not the first chord of beam group
                              // and slur direction is same as end chord (stem side)
                              // and start chordrest is not a grace chord

                              // in these cases, layout end of slur to stem

                              qreal sh = stem2->height() + _spatium;
                              if (_up)
                                    yo = ec->downNote()->pos().y() - sh;
                              else
                                    yo = ec->upNote()->pos().y() + sh;
                              xo = stem2->pos().x();
                              }
                        else
                              {
                              // slur was not aligned to stem or start and end have different direction
                              // AND
                              // end chord is not beamed or is first chord of beam group
                              // or slur direction is opposite that of end chord

                              // if stem and slur are both down,
                              // we need to clear stem horizontally
                              if (!ec->up() && !_up)
                                    xo = -_spatium * .3 + note2->x();

                              //
                              // handle case: stem up   - stem down
                              //              stem down - stem up
                              //
                              if ((scr->up() != ec->up()) && (ec->up() == _up)) {
                                    // start and end chord have opposite direction
                                    // and slur direction is same as end chord
                                    // (so slur end on stem side)

                                    // float the end point along the stem to follow direction of movement
                                    // see for example Gould p. 111

                                    Note* n1 = 0;
                                    if (sc)
                                          n1 = sc->up() ? sc->upNote() : sc->downNote();
                                    Note* n2 = ec->up() ? ec->upNote() : ec->downNote();

                                    qreal yd = n2->pos().y() - (n1 ? n1->pos().y() : startCR()->pos().y());
                                    yd *= .5;

                                    qreal mh = stem2->height();
                                    if (_up && yd > 0.0)
                                          yo = qMax(yo - yd, ec->downNote()->pos().y() - mh - _spatium);
                                    else if (!_up && yd < 0.0)
                                          yo = qMin(yo - yd, ec->upNote()->pos().y() + mh + _spatium);
                                    }
                              else if (ec->up() != _up) {
                                    // slur opposite direction from chord
                                    // avoid articulations
                                    yo = fixArticulations(yo, ec, __up);
                                    }

                              }
                        }
                  else if (ec && ec->up() != _up) {
                        // slur opposite direction from chord
                        // avoid articulations
                        yo = fixArticulations(yo, ec, __up);
                        }

                  sp->p2 += QPointF(xo, yo);
                  }
            }
      }

//---------------------------------------------------------
//   Slur
//---------------------------------------------------------

Slur::Slur(Score* s)
   : SlurTie(s)
      {
      setAnchor(Anchor::CHORD);
      }

//---------------------------------------------------------
//   Slur
//---------------------------------------------------------

Slur::~Slur()
      {
      }

//---------------------------------------------------------
//   write
//---------------------------------------------------------

void Slur::write(XmlWriter& xml) const
      {
      if (broken()) {
            qDebug("broken slur not written");
            return;
            }
      if (!xml.canWrite(this))
            return;
      xml.stag(QString("Slur id=\"%1\"").arg(xml.spannerId(this)));
      SlurTie::writeProperties(xml);
      xml.etag();
      }

//---------------------------------------------------------
//   read
//---------------------------------------------------------

void Slur::read(XmlReader& e)
      {
      setTrack(e.track());      // set staff
      e.addSpanner(e.intAttribute("id"), this);
      while (e.readNextStartElement()) {
            const QStringRef& tag(e.name());
            if (tag == "track2")
                  setTrack2(e.readInt());
            else if (tag == "startTrack")       // obsolete
                  setTrack(e.readInt());
            else if (tag == "endTrack")         // obsolete
                  e.readInt();
            else if (!SlurTie::readProperties(e))
                  e.unknown();
            }
      if (track2() == -1)
            setTrack2(track());
      }

//---------------------------------------------------------
//   chordsHaveTie
//---------------------------------------------------------

static bool chordsHaveTie(Chord* c1, Chord* c2)
      {
      int n1 = c1->notes().size();
      for (int i1 = 0; i1 < n1; ++i1) {
            Note* n1 = c1->notes().at(i1);
            int n2 = c2->notes().size();
            for (int i2 = 0; i2 < n2; ++i2) {
                  Note* n2 = c2->notes().at(i2);
                  if (n1->tieFor() && n1->tieFor() == n2->tieBack())
                        return true;
                  }
            }
      return false;
      }

//---------------------------------------------------------
//   directionMixture
//---------------------------------------------------------

static bool isDirectionMixture(Chord* c1, Chord* c2)
      {
      bool up = c1->up();
      for (Segment* seg = c1->segment(); seg; seg = seg->next(SegmentType::ChordRest)) {
            Element* e = seg->element(c1->track());
            if (!e || !e->isChord())
                  continue;
            Chord* c = toChord(e);
            if (c->up() != up)
                  return true;
            if (seg == c2->segment())
                  break;
            }
      return false;
      }

//---------------------------------------------------------
//   layoutSystem
//    layout slurSegment for system
//---------------------------------------------------------

SpannerSegment* Slur::layoutSystem(System* system)
      {
      int stick = system->firstMeasure()->tick();
      int etick = system->lastMeasure()->endTick();

      SlurSegment* slurSegment = 0;
      for (SpannerSegment* ss : segments) {
            if (!ss->system()) {
                  slurSegment = toSlurSegment(ss);
                  break;
                  }
            }
      if (!slurSegment) {
            slurSegment = new SlurSegment(score());
            add(slurSegment);
            }
      slurSegment->setSystem(system);
      slurSegment->setSpanner(this);

      SpannerSegmentType sst;
      if (tick() >= stick) {
            //
            // this is the first call to layoutSystem,
            // processing the first line segment
            //
            if (track2() == -1)
                  setTrack2(track());
            if (startCR() == 0 || startCR()->measure() == 0) {
                  qDebug("Slur::layout(): track %d-%d  %p - %p tick %d-%d null start anchor",
                     track(), track2(), startCR(), endCR(), tick(), tick2());
                  return slurSegment;
                  }
            if (endCR() == 0) {     // sanity check
                  setEndElement(startCR());
                  setTick2(tick());
                  }
            switch (_slurDirection) {
                  case Direction::UP:
                        _up = true;
                        break;
                  case Direction::DOWN:
                        _up = false;
                        break;
                  case Direction::AUTO:
                        {
                        //
                        // assumption:
                        // slurs have only chords or rests as start/end elements
                        //
                        if (startCR() == 0 || endCR() == 0) {
                              _up = true;
                              break;
                              }
                        Chord* c1 = startCR()->isChord() ? toChord(startCR()) : 0;
                        Chord* c2 = endCR()->isChord()   ? toChord(endCR())   : 0;

                        _up = !(startCR()->up());

                        Measure* m1 = startCR()->measure();
                        if ((endCR()->tick() - startCR()->tick()) > m1->ticks()) // long slurs are always above
                              _up = true;
                        else
                              _up = !startCR()->up();

                        if (c1 && c2 && isDirectionMixture(c1, c2) && !c1->isGrace()) {
                              // slurs go above if start and end note have different stem directions,
                              // but grace notes are exceptions
                              _up = true;
                              }
                        else if (m1->hasVoices(startCR()->staffIdx()) && c1 && !c1->isGrace()) {
                              // in polyphonic passage, slurs go on the stem side
                              _up = startCR()->up();
                              }
                        else if (c1 && c2 && chordsHaveTie(c1, c2)) {
                              // could confuse slur with tie, put slur on stem side
                              _up = startCR()->up();
                              }
                        }
                        break;
                  }
            sst = tick2() < etick ? SpannerSegmentType::SINGLE : SpannerSegmentType::BEGIN;
            }
      else if (tick() < stick && tick2() > etick)
            sst = SpannerSegmentType::MIDDLE;
      else
            sst = SpannerSegmentType::END;
      slurSegment->setSpannerSegmentType(sst);

      SlurPos sPos;
      slurPos(&sPos);

      switch (sst) {
            case SpannerSegmentType::SINGLE:
                  slurSegment->layoutSegment(sPos.p1, sPos.p2);
                  break;
            case SpannerSegmentType::BEGIN:
                  slurSegment->layoutSegment(sPos.p1, QPointF(system->bbox().width(), sPos.p1.y()));
                  break;
            case SpannerSegmentType::MIDDLE: {
                  qreal x1 = firstNoteRestSegmentX(system);
                  qreal x2 = system->bbox().width();
                  qreal y  = staffIdx() > system->staves()->size() ? system->y() : system->staff(staffIdx())->y();
                  slurSegment->layoutSegment(QPointF(x1, y), QPointF(x2, y));
                  }
                  break;
            case SpannerSegmentType::END:
                  slurSegment->layoutSegment(QPointF(firstNoteRestSegmentX(system), sPos.p2.y()), sPos.p2);
                  break;
            }

      QList<SpannerSegment*> sl;
      for (SpannerSegment* ss : segments) {
            if (ss->system())
                  sl.push_back(ss);
            else {
                  qDebug("delete spanner segment %s", ss->name());
                  delete ss;
                  }
            }
      segments.swap(sl);
      return slurSegment;
      }

//---------------------------------------------------------
//   layout
//---------------------------------------------------------

void Slur::layout()
      {
      if (track2() == -1)
            setTrack2(track());

      qreal _spatium = spatium();

      if (score() == gscore || tick() == -1) {
            //
            // when used in a palette, slur has no parent and
            // tick and tick2 has no meaning so no layout is
            // possible and needed
            //
            SlurSegment* s;
            if (spannerSegments().empty()) {
                  s = new SlurSegment(score());
                  s->setTrack(track());
                  add(s);
                  }
            else {
                  s = frontSegment();
                  }
            s->setSpannerSegmentType(SpannerSegmentType::SINGLE);
            s->layoutSegment(QPointF(0, 0), QPointF(_spatium * 6, 0));
            setbbox(frontSegment()->bbox());
            return;
            }

      if (startCR() == 0 || startCR()->measure() == 0) {
            qDebug("Slur::layout(): track %d-%d  %p - %p tick %d-%d null start anchor",
               track(), track2(), startCR(), endCR(), tick(), tick2());
            return;
            }
      if (endCR() == 0) {     // sanity check
            setEndElement(startCR());
            setTick2(tick());
            }
      switch (_slurDirection) {
            case Direction::UP:
                  _up = true;
                  break;
            case Direction::DOWN:
                  _up = false;
                  break;
            case Direction::AUTO:
                  {
                  //
                  // assumption:
                  // slurs have only chords or rests as start/end elements
                  //
                  if (startCR() == 0 || endCR() == 0) {
                        _up = true;
                        break;
                        }
                  Measure* m1 = startCR()->measure();

                  Chord* c1 = startCR()->isChord() ? toChord(startCR()) : 0;
                  Chord* c2 = endCR()->isChord()   ? toChord(endCR())   : 0;

                  _up = !(startCR()->up());

                  if ((endCR()->tick() - startCR()->tick()) > m1->ticks()) {
                        // long slurs are always above
                        _up = true;
                        }
                  else
                        _up = !(startCR()->up());

                  if (c1 && c2 && isDirectionMixture(c1, c2) && (c1->noteType() == NoteType::NORMAL)) {
                        // slurs go above if start and end note have different stem directions,
                        // but grace notes are exceptions
                        _up = true;
                        }
                  else if (m1->hasVoices(startCR()->staffIdx()) && c1 && c1->noteType() == NoteType::NORMAL) {
                        // in polyphonic passage, slurs go on the stem side
                        _up = startCR()->up();
                        }
                  else if (c1 && c2 && chordsHaveTie(c1, c2)) {
                        // could confuse slur with tie, put slur on stem side
                        _up = startCR()->up();
                        }
                  }
                  break;
            }

      SlurPos sPos;
      slurPos(&sPos);

      const QList<System*>& sl = score()->systems();
      ciSystem is = sl.begin();
      while (is != sl.end()) {
            if (*is == sPos.system1)
                  break;
            ++is;
            }
      if (is == sl.end())
            qDebug("Slur::layout  first system not found");
      setPos(0, 0);

      //---------------------------------------------------------
      //   count number of segments, if no change, all
      //    user offsets (drags) are retained
      //---------------------------------------------------------

      unsigned nsegs = 1;
      for (ciSystem iis = is; iis != sl.end(); ++iis) {
            if ((*iis)->vbox())
                  continue;
            if (*iis == sPos.system2)
                  break;
            ++nsegs;
            }

      fixupSegments(nsegs);

      for (int i = 0; is != sl.end(); ++i, ++is) {
            System* system  = *is;
            if (system->vbox()) {
                  --i;
                  continue;
                  }
            SlurSegment* segment = segmentAt(i);
            segment->setSystem(system);

            // case 1: one segment
            if (sPos.system1 == sPos.system2) {
                  segment->setSpannerSegmentType(SpannerSegmentType::SINGLE);
                  segment->layoutSegment(sPos.p1, sPos.p2);
                  }
            // case 2: start segment
            else if (i == 0) {
                  segment->setSpannerSegmentType(SpannerSegmentType::BEGIN);
                  qreal x = system->bbox().width();
                  segment->layoutSegment(sPos.p1, QPointF(x, sPos.p1.y()));
                  }
            // case 3: middle segment
            else if (i != 0 && system != sPos.system2) {
                  segment->setSpannerSegmentType(SpannerSegmentType::MIDDLE);
                  qreal x1 = firstNoteRestSegmentX(system);
                  qreal x2 = system->bbox().width();
                  qreal y  = staffIdx() > system->staves()->size() ? system->y() : system->staff(staffIdx())->y();
                  segment->layoutSegment(QPointF(x1, y), QPointF(x2, y));
                  }
            // case 4: end segment
            else {
                  segment->setSpannerSegmentType(SpannerSegmentType::END);
                  qreal x = firstNoteRestSegmentX(system);
                  segment->layoutSegment(QPointF(x, sPos.p2.y()), sPos.p2);
                  }
            if (system == sPos.system2)
                  break;
            }
      setbbox(spannerSegments().empty() ? QRectF() : frontSegment()->bbox());
      }

//---------------------------------------------------------
//   setTrack
//---------------------------------------------------------

void Slur::setTrack(int n)
      {
      Element::setTrack(n);
      for (SpannerSegment* ss : spannerSegments())
            ss->setTrack(n);
      }

//---------------------------------------------------------
//   readProperties
//---------------------------------------------------------

bool Slur::readProperties(XmlReader& e)
      {
      const QStringRef& tag(e.name());

      if (tag == "SlurSegment") {
            int idx = e.intAttribute("no", 0);
            int n = spannerSegments().size();
            for (int i = n; i < idx; ++i)
                  add(new SlurSegment(score()));
            SlurSegment* segment = new SlurSegment(score());
            segment->setAutoplace(false);
            segment->read(e);
            add(segment);
            }
      else if (!SlurTie::readProperties(e))
            return false;
      return true;
      }

}