qgsdecoratedscrollbar.h

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/***************************************************************************
    qgsdecoratedscrollbar.h
     --------------------------------------
    Date                 : May 2024
    Copyright            : (C) 2024 by Nyall Dawson
    Email                : nyall dot dawson at gmail dot com
 ***************************************************************************
 *                                                                         *
 *   This program is free software; you can redistribute it and/or modify  *
 *   it under the terms of the GNU General Public License as published by  *
 *   the Free Software Foundation; either version 2 of the License, or     *
 *   (at your option) any later version.                                   *
 *                                                                         *
 ***************************************************************************/
 
#ifndef QGSDECORATEDSCROLLBAR_H
#define QGSDECORATEDSCROLLBAR_H
 
#include "qgis_gui.h"
#include "qgis_sip.h"
 
#include <QColor>
#include <QHash>
#include <QMap>
#include <QPointer>
#include <QWidget>
 
class QScrollBar;
class QAbstractScrollArea;
class QgsScrollBarHighlightOverlay;
 
// ported from QtCreator's HighlightScrollBarController implementation

class GUI_EXPORT QgsScrollBarHighlight
{
  public:
    enum class Priority : int
    {
      Invalid = -1,       
      LowPriority = 0,    
      NormalPriority = 1, 
      HighPriority = 2,   
      HighestPriority = 3 
    };

    QgsScrollBarHighlight( int category, int position, const QColor &color, QgsScrollBarHighlight::Priority priority = QgsScrollBarHighlight::Priority::NormalPriority );
 
    QgsScrollBarHighlight() = default;

    int category = -1;

    int position = -1;

    QColor color;

    QgsScrollBarHighlight::Priority priority = QgsScrollBarHighlight::Priority::Invalid;
};

class GUI_EXPORT QgsScrollBarHighlightController
{
  public:
    QgsScrollBarHighlightController();
    ~QgsScrollBarHighlightController();

    QScrollBar *scrollBar() const;

    QAbstractScrollArea *scrollArea() const;

    void setScrollArea( QAbstractScrollArea *scrollArea );

    double lineHeight() const;

    void setLineHeight( double height );

    double visibleRange() const;

    void setVisibleRange( double visibleRange );

    double margin() const;

    void setMargin( double margin );

    QHash<int, QVector<QgsScrollBarHighlight>> highlights() const SIP_SKIP;

    void addHighlight( const QgsScrollBarHighlight &highlight );

    void removeHighlights( int category );

    void removeAllHighlights();
 
  private:
    QHash<int, QVector<QgsScrollBarHighlight>> mHighlights;
    double mLineHeight = 0.0;
    double mVisibleRange = 0.0; // in pixels
    double mMargin = 0.0;       // in pixels
    QAbstractScrollArea *mScrollArea = nullptr;
    QPointer<QgsScrollBarHighlightOverlay> mOverlay;
};

#ifndef SIP_RUN
class QgsScrollBarHighlightOverlay : public QWidget
{
    Q_OBJECT
 
  public:
    QgsScrollBarHighlightOverlay( QgsScrollBarHighlightController *scrollBarController );
 
    void doResize();
    void doMove();
    void scheduleUpdate();
 
  protected:
    void paintEvent( QPaintEvent *paintEvent ) override;
    bool eventFilter( QObject *object, QEvent *event ) override;
 
  private:
    void drawHighlights( QPainter *painter, int docStart, int docSize, double docSizeToHandleSizeRatio, int handleOffset, const QRect &viewport );
    void updateCache();
    QRect overlayRect() const;
    QRect handleRect() const;
 
    // line start to line end
    QMap<QgsScrollBarHighlight::Priority, QMap<QRgb, QMap<int, int>>> mHighlightCache;
 
    inline QScrollBar *scrollBar() const { return mHighlightController->scrollBar(); }
    QgsScrollBarHighlightController *mHighlightController = nullptr;
    bool mIsCacheUpdateScheduled = true;
};
#endif
 
#endif // QGSDECORATEDSCROLLBAR_H