renderarea.h

#ifndef RENDERAREA_H
#define RENDERAREA_H

#include <QWidget>
#include <QColor>
#include <QPen>
#include <math.h>

class RenderArea : public QWidget
{
    Q_OBJECT
public:
    explicit RenderArea(QWidget *parent = nullptr);

    QSize minimumSizeHint() const Q_DECL_OVERRIDE;
    QSize sizeHint() const Q_DECL_OVERRIDE;

    enum ShapeType {
        Astroid,
        Cycloid,
        HuygensCycloid,
        HypoCycloid,
        Line,
        Circle,
        Ellipse,
        Fancy,
        Starfish,
        Cloud1,
        Cloud2
    };

    void setBackgroundColor (QColor color) { mBackgroundColor = color; }    //  setter
    QColor backgroundColor () const { return mBackgroundColor; }  //  getter

    void setShapeColor (QColor color) { mPen.setColor(color); }
    QColor shapeColor () const { return mPen.color(); }

    void setShape (ShapeType shape) { mShape = shape; on_shape_changed (); }
    ShapeType shape () const { return mShape; }

    void setScale (float scale) { mScale = scale; repaint (); }
    float scale () const { return mScale; }

    void setIntervalLength (float length) { mIntervalLength = length; repaint(); }
    float intervalLength () const { return mIntervalLength; }

    void setStepCount (int count) { mStepCount = count; repaint(); }
    int stepCount () const { return mStepCount; }


signals:

protected:
     void paintEvent(QPaintEvent *event) Q_DECL_OVERRIDE;

private:
     void on_shape_changed ();
     QPointF compute (float t);  //  dispatch function based on mShape's type
     QPointF compute_astroid (float t);
     QPointF compute_cycloid (float t);
     QPointF compute_huygens (float t);
     QPointF compute_hypo (float t);
     QPointF compute_line (float t);
     QPointF compute_circle(float t);
     QPointF compute_ellipse(float t);
     QPointF compute_fancy(float t);
     QPointF compute_starfish(float t);
     QPointF compute_cloud1 (float t);
     QPointF compute_cloud2 (float t);
     QPointF compute_cloud_with_sign (float t, float sign);

private:
     QColor mBackgroundColor;
     QPen   mPen;
     ShapeType mShape;

     double mIntervalLength;
     double mScale;
     int   mStepCount;

public slots:
};

#endif // RENDERAREA_H