    //=============================================================================
    //  MuseScore
    //  Music Composition & Notation
    //
    //  Copyright (C) 2002-2009 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
    //=============================================================================

    #ifndef __SCANVAS_H__
    #define __SCANVAS_H__

    #include "globals.h"
    #include "libmscore/element.h"
    #include "libmscore/durationtype.h"
    #include "libmscore/mscore.h"
    #include "libmscore/mscoreview.h"
    #include "libmscore/pos.h"

    namespace Ms {

    class ChordRest;
    class Rest;
    class Element;
    class Page;
    class XmlWriter;
    class Note;
    class Lasso;
    class FotoLasso;
    class ShadowNote;
    class Segment;
    class Measure;
    class System;
    class Score;
    class ScoreView;
    class Text;
    class MeasureBase;
    class Staff;
    class OmrView;
    class PositionCursor;
    class ContinuousPanel;
    class Tuplet;
    class FretDiagram;
    class Bend;
    class TremoloBar;

    #ifdef Q_OS_MAC
    #define CONTROL_MODIFIER Qt::AltModifier
    #else
    #define CONTROL_MODIFIER Qt::ControlModifier
    #endif

    enum class Grip : int;
    enum class POS : char;
    enum class MagIdx : char;

    //---------------------------------------------------------
    //   ViewState
    //---------------------------------------------------------

    enum class ViewState {
          NORMAL,
          DRAG,
          DRAG_OBJECT,
          EDIT,
          DRAG_EDIT,
          LASSO,
          NOTE_ENTRY,
          PLAY,
          ENTRY_PLAY,

          FOTO,
          FOTO_DRAG,
          FOTO_DRAG_EDIT,
          FOTO_DRAG_OBJECT,
          FOTO_LASSO,
          };

    enum class TEXT : char {
          TITLE,
          SUBTITLE,
          COMPOSER,
          POET,
          PART,
          SYSTEM,
          STAFF,
          EXPRESSION,
          REHEARSAL_MARK,
          INSTRUMENT_CHANGE,
          FINGERING
          };

    //---------------------------------------------------------
    //   ScoreView
    //---------------------------------------------------------

    class ScoreView : public QWidget, public MuseScoreView {
          Q_OBJECT

          ViewState state;
          OmrView* _omrView;

          // the next elements are used during dragMove to give some visual
          // feedback:
          //    dropTarget:       if valid, the element is drawn in a different color
          //                      to mark it as a valid drop target
          //    dropRectangle:    if valid, the rectangle is filled with a
          //                      color to visualize a valid drop area
          //    dropAnchor:       if valid the line is drawn from the current
          //                      cursor position to the current anchor point
          // Note:
          //    only one of the elements is active during drag

          const Element* dropTarget;    ///< current drop target during dragMove
          QRectF dropRectangle;         ///< current drop rectangle during dragMove
          QLineF dropAnchor;            ///< line to current anchor point during dragMove

          QTransform _matrix, imatrix;
          MagIdx _magIdx;

          QFocusFrame* focusFrame;

          EditData editData;

          //--input state:
          PositionCursor* _cursor;
          ShadowNote* shadowNote;

          // Realtime state:      Note: always set allowRealtimeRests to desired value before starting a timer.
          QTimer* realtimeTimer;   // multi-shot timer for advancing in automatic realtime mode
          QTimer* extendNoteTimer; // single-shot timer for initial advancement when a note is held
          bool allowRealtimeRests; // Allow entering rests in realtime mode? (See note above)

          // Loop In/Out marks in the score
          PositionCursor* _curLoopIn;
          PositionCursor* _curLoopOut;

          // Continuous panel
          ContinuousPanel* _continuousPanel;

          Lasso* lasso;           ///< temporarily drawn lasso selection
          FotoLasso* _foto;

          QColor _bgColor;
          QColor _fgColor;
          QPixmap* _bgPixmap;
          QPixmap* _fgPixmap;

          virtual void paintEvent(QPaintEvent*);
          void paint(const QRect&, QPainter&);

          void objectPopup(const QPoint&, Element*);
          void measurePopup(const QPoint&, Measure*);

          void saveChord(XmlWriter&);

          virtual bool event(QEvent* event) override;
          virtual bool gestureEvent(QGestureEvent*);            // ??
          virtual void resizeEvent(QResizeEvent*) override;
          virtual void dragEnterEvent(QDragEnterEvent*) override;
          virtual void dragLeaveEvent(QDragLeaveEvent*) override;
          virtual void dragMoveEvent(QDragMoveEvent*) override;
          virtual void dropEvent(QDropEvent*) override;
          virtual void focusInEvent(QFocusEvent*) override;
          virtual void focusOutEvent(QFocusEvent*) override;

          virtual void wheelEvent(QWheelEvent*) override;
          virtual void mouseMoveEvent(QMouseEvent*) override;
          virtual void mousePressEvent(QMouseEvent*) override;
          virtual void mouseReleaseEvent(QMouseEvent*) override;
          virtual void mouseDoubleClickEvent(QMouseEvent*);

          virtual void keyPressEvent(QKeyEvent*) override;
          virtual void keyReleaseEvent(QKeyEvent*) override;

          virtual void contextMenuEvent(QContextMenuEvent*) override;

          void mousePressEventNormal(QMouseEvent*);
          void escapeCmd();

          void constraintCanvas(int *dxx, int *dyy);
          void contextItem(Element*);
          void lassoSelect();

          void setShadowNote(const QPointF&);
          void drawElements(QPainter& p,const QList<Element*>& el);
          bool dragTimeAnchorElement(const QPointF& pos);
          bool dragMeasureAnchorElement(const QPointF& pos);
          void updateGrips();
          virtual void lyricsTab(bool back, bool end, bool moveOnly) override;
          virtual void lyricsReturn() override;
          virtual void lyricsEndEdit() override;
          virtual void lyricsUpDown(bool up, bool end) override;
          virtual void lyricsMinus() override;
          virtual void lyricsUnderscore() override;
          void harmonyEndEdit();
          void harmonyTab(bool back);
          void harmonyBeatsTab(bool noterest, bool back);
          void harmonyTicksTab(int ticks);
          void figuredBassTab(bool meas, bool back);
          void figuredBassTicksTab(int ticks);
          void figuredBassEndEdit();
          void realtimeAdvance(bool allowRests);
          void cmdAddFret(int fret);
          void cmdAddChordName();
          void cmdAddText(TEXT style);
          void cmdEnterRest(const TDuration&);
          void cmdEnterRest();
          void cmdTuplet(int n, ChordRest*);
          void cmdTuplet(int);
          void cmdCreateTuplet(ChordRest* cr, Tuplet* tuplet);
          void cmdRepeatSelection();
          void cmdChangeEnharmonic(bool);

          MeasureBase* insertMeasure(ElementType, MeasureBase*);
          MeasureBase* checkSelectionStateForInsertMeasure();

          void appendMeasures(int, ElementType);
          MeasureBase* appendMeasure(ElementType);
          void cmdInsertMeasure(ElementType);
          void createElementPropertyMenu(Element* e, QMenu*);
          void genPropertyMenu1(Element* e, QMenu* popup);
          void genPropertyMenuText(Element* e, QMenu* popup);
          void elementPropertyAction(const QString&, Element* e);
          void paintPageBorder(QPainter& p, Page* page);
          bool dropCanvas(Element*);
          void editCmd(const QString&);
          void setLoopCursor(PositionCursor* curLoop, int tick, bool isInPos);
          void cmdMoveCR(bool left);
          void cmdGotoElement(Element*);
          bool checkCopyOrCut();
          QVariant inputMethodQuery(Qt::InputMethodQuery query) const;
          void startFotomode();
          void stopFotomode();
          void startFotoDrag();
          void endFotoDrag();
          void endFotoDragEdit();

          virtual void startEdit();
          void endEdit();

          void startDrag();
          void endDrag();

          void endDragEdit();

          void startNoteEntry();
          virtual void startNoteEntryMode() override;
          void endNoteEntry();

          void endLasso();

       private slots:
          void posChanged(POS pos, unsigned tick);
          void loopToggled(bool);
          void triggerCmdRealtimeAdvance();
          void cmdRealtimeAdvance();
          void extendCurrentNote();
          void seqStopped();

       public slots:
          void setViewRect(const QRectF&);

          void deselectAll();

          void editCopy();
          void editCut();
          void editPaste();
          void editSwap();

          void normalCut();
          void normalCopy();
          void fotoModeCopy();
          bool normalPaste();
          void normalSwap();

          void cloneElement(Element* e);
          void doFotoDragEdit(QMouseEvent* ev);

          void updateContinuousPanel();
          void ticksTab(int ticks);     // helper function

       signals:
          void viewRectChanged();
          void scaleChanged(double);
          void offsetChanged(double, double);
          void sizeChanged();

       public:
          ScoreView(QWidget* parent = 0);
          ~ScoreView();

          QPixmap* fgPixmap() { return _fgPixmap; }

          virtual void startEdit(Element*, Grip) override;
          virtual void startEditMode(Element*) override;

          void moveCursor(int tick);
          int cursorTick() const;
          void setCursorOn(bool);
          void setBackground(QPixmap*);
          void setBackground(const QColor&);
          void setForeground(QPixmap*);
          void setForeground(const QColor&);

          Page* addPage();
          void modifyElement(Element* obj);
          virtual void setScore(Score* s);
          virtual void removeScore()  { _score = 0; }

          void setMag(qreal m);
          bool navigatorVisible() const;
          void cmd(const QAction*);
          void cmd(const char*);

          void startUndoRedo(bool);
          void zoomStep(qreal step, const QPoint& pos);
          void zoom(qreal _mag, const QPointF& pos);
          void contextPopup(QContextMenuEvent* ev);
          bool editKeyLyrics(QKeyEvent*);
          void dragScoreView(QMouseEvent* ev);
          void doDragElement(QMouseEvent* ev);
          void doDragLasso(QMouseEvent* ev);
          void doDragFoto(QMouseEvent* ev);
          void doDragEdit(QMouseEvent* ev);
          bool testElementDragTransition(QMouseEvent* ev);
          bool fotoEditElementDragTransition(QMouseEvent* ev);
          bool editScoreViewDragTransition(QMouseEvent* e);
          bool editSelectTransition(QMouseEvent* me);
          void addSlur();
          virtual void cmdAddSlur(ChordRest*, ChordRest*) override;
          virtual void cmdAddHairpin(HairpinType) override;
          void cmdAddNoteLine();

          bool noteEntryMode() const { return state == ViewState::NOTE_ENTRY; }
          bool editMode() const      { return state == ViewState::EDIT; }
          bool fotoMode() const;

          virtual void setDropRectangle(const QRectF&);
          virtual void setDropTarget(const Element*) override;
          void setDropAnchor(const QLineF&);
          const QTransform& matrix() const  { return _matrix; }
          qreal mag() const;
          qreal lmag() const;
          MagIdx magIdx() const             { return _magIdx; }
          void setMag(MagIdx idx, double mag);
          qreal xoffset() const;
          qreal yoffset() const;
          void setOffset(qreal x, qreal y);
          QSizeF fsize() const;
          void pageNext();
          void pagePrev();
          void pageTop();
          void pageEnd();
          QPointF toLogical(const QPoint& p) const   { return imatrix.map(QPointF(p)); }
          QPointF toPhysical(const QPointF& p) const {return _matrix.map(p); }
          QRectF toLogical(const QRectF& r) const    { return imatrix.mapRect(r); }
          QRect toPhysical(const QRectF& r) const    { return _matrix.mapRect(r).toRect(); }

          bool searchMeasure(int i);
          bool searchPage(int i);
          bool searchRehearsalMark(const QString& s);
          void gotoMeasure(Measure*);
          void setFocusRect();
          void changeVoice(int voice);
          virtual void drawBackground(QPainter* p, const QRectF& r) const;
          bool fotoScoreViewDragTest(QMouseEvent*);
          bool fotoScoreViewDragRectTest(QMouseEvent*);
          void doDragFotoRect(QMouseEvent*);
          void fotoContextPopup(QContextMenuEvent*);
          bool fotoRectHit(const QPoint& p);
          void paintRect(bool printMode, QPainter& p, const QRectF& r, double mag);
          bool saveFotoAs(bool printMode, const QRectF&);
          void fotoDragDrop(QMouseEvent*);
          void changeEditElement(Element*);

          void cmdAppendMeasures(int, ElementType);
          void cmdInsertMeasures(int, ElementType);

          void cmdAddRemoveBreaks();
          void cmdCopyLyricsToClipboard();

          ScoreState mscoreState() const;
          void setCursorVisible(bool v);
          void showOmr(bool flag);
          void midiNoteReceived(int pitch, bool chord, int velocity);

          virtual void moveCursor() override;

          virtual void layoutChanged();
          virtual void dataChanged(const QRectF&);
          virtual void updateAll()    { update(); }
          virtual void adjustCanvasPosition(const Element* el, bool playBack, int staff = -1) override;
          virtual void setCursor(const QCursor& c) { QWidget::setCursor(c); }
          virtual QCursor cursor() const { return QWidget::cursor(); }
          void loopUpdate(bool val)   {  loopToggled(val); }

          void updateShadowNotes();

          OmrView* omrView() const        { return _omrView; }
          void setOmrView(OmrView* v)     { _omrView = v;    }
          FotoLasso* fotoLasso() const    { return _foto;    }
          Element* getEditElement();

          virtual Element* elementNear(QPointF);
          void editFretDiagram(FretDiagram*);
          void editBendProperties(Bend*);
          void editTremoloBarProperties(TremoloBar*);
          EditData& getEditData()        { return editData; }
          void changeState(ViewState);

          virtual const QRect geometry() const override { return QWidget::geometry(); }
          };

    } // namespace Ms
    #endif

↑ V762 It is possible a virtual function was overridden incorrectly. See third argument of function 'adjustCanvasPosition' in derived class 'ScoreView' and base class 'MuseScoreView'.