canvas_view.h

#pragma once
 
#include <QGraphicsView>
#include <QKeyEvent>
#include <QWheelEvent>
 
#include "widgets/settings_manager.h"
 
class Canvas;

class CanvasView : public QGraphicsView
{
  Q_OBJECT
public:
  CanvasView(QWidget* parent = nullptr);

  QPointF getCenter() const;

  qreal getScale() const;

  void setScale(qreal scale);

  void zoom(float scaleFactor);

  void centerOn(const QPointF& pos);

  void centerOn(const QGraphicsItem* item);

  void onSettingsChanged(const AppearanceSettings& settings);
 
protected:
  void keyPressEvent(QKeyEvent*) override;

  void keyReleaseEvent(QKeyEvent*) override;

  void mouseMoveEvent(QMouseEvent*) override;

  void mousePressEvent(QMouseEvent*) override;

  void mouseReleaseEvent(QMouseEvent*) override;

  void wheelEvent(QWheelEvent*) override;

  void drawBackground(QPainter* painter, const QRectF& rect) override;
 
private:
  bool mDoMousePanning;

  bool mDoKeyZoom;

  bool mShowGrid;

  QPoint mLastMousePos;

  qreal mZoomDelta;

  qreal mZoomKey;

  qreal mMinZoom;

  qreal mMaxZoom;

  Qt::MouseButton mPanButton;

  void zoomIn();

  void zoomOut();

  void resetZoom();

  qreal quantisedScale(qreal proposedScale) const;

  void setMaxSize();
};