QCustomParabola

// qcustomparabola.h
#ifndef QCUSTOMPARABOLA_H
#define QCUSTOMPARABOLA_H

#include <qcustomplot.h>

class QCustomParabola
{
    QVector < double > x, y;
    double x_min, x_max,
    a, b, c, y_min, y_max;
    int accuracy;
    QCPGraph *parabola;
    QCustomPlot *plot;
    QString name;
    void fillXY();
    QBrush brush;
    QPen pen;
    QColor color;
    QCPItemText *headLabel;
public:
    QCustomParabola( double __x_min,
                     double __x_max,
                     int __accuracy,
                     double __a,
                     double __b,
                     double __c, QString __name,
                     QCustomPlot *__plot );
    QCustomParabola( QCustomPlot *__plot );
    ~ QCustomParabola();

public slots:
    void setXRange( double __x_min, double __x_max );
    void setAccuracy( int __accuracy );
    void setABC( double __a,
                 double __b,
                 double __c );
    void setName( QString __name );
    void setBrush( QBrush __brush );
    void setPen( QPen __pen );
    void setColor( QColor __color );
    void show();
    void showHead( bool visible );

    double getXMIN();
    double getXMAX();
    double getYMAX();
    double getYMIN();
    double getA();
    double getB();
    double getC();
    QString getName();
    double getHeadX();
    double getHeadY();
    double getDiscriminant();
    QVector < double > getX();
    QVector < double > getY();
    QCPGraph *getGraph();
    QBrush getBrush();
    QPen getPen();
};

#endif // QCUSTOMPARABOLA_H

//--------------------------------------------------------------------------------------------------------------------

// qcustomparabola.cpp
#include "qcustomparabola.h"

void QCustomParabola::fillXY()
{
    int k = 0;
    y_min = 0;
    for ( double i = x_min * accuracy; i <= x_max * accuracy; ++i ) {
        x.push_back( i/accuracy) ;
        y.push_back( a * x[k] * x[k] + b * x[k] + c);
        if (y[k] < y_min)
            y_min = y[k];
        k++;
    }
    y_max = y[y.size() - 1];
}

QCustomParabola::QCustomParabola(double __x_min,
                                 double __x_max,
                                 int __accuracy,
                                 double __a,
                                 double __b,
                                 double __c,
                                 QString __name,
                                 QCustomPlot *__plot )
{
    x.clear(); y.clear();
    x_min = __x_min;
    x_max = __x_max;
    accuracy = __accuracy;
    a = __a;
    b = __b;
    c = __c;
    name = __name;

    fillXY();
    plot = __plot;
    parabola = plot->addGraph();
    parabola->setName( __name );
    brush = parabola->brush();
    pen = parabola->pen();
    parabola->setData( x, y );
}

QCustomParabola::QCustomParabola( QCustomPlot *__plot )
{
    plot = __plot;
    parabola = plot->addGraph();
}

QCustomParabola::~QCustomParabola()
{

}

void QCustomParabola::setXRange(double __x_min,
                                double __x_max)
{
    x_min = __x_min;
    x_max = __x_max;
}

void QCustomParabola::setAccuracy(int __accuracy)
{
    accuracy = __accuracy;
}

void QCustomParabola::setABC(double __a, double __b, double __c)
{
    a = __a;
    b = __b;
    c = __c;
}

void QCustomParabola::setName(QString __name)
{
    name = __name;
    parabola->setName( name );
}

void QCustomParabola::setBrush(QBrush __brush)
{
    brush = __brush;
    parabola->setBrush( brush );
}

void QCustomParabola::setPen(QPen __pen)
{
    pen = __pen;
    parabola->setPen( pen );

}

void QCustomParabola::setColor(QColor __color)
{
    color = __color;
    pen = QPen( color );
    parabola->setPen( QPen( color ) );
}

void QCustomParabola::show()
{
    x.clear(); y.clear();
    fillXY();
    parabola->setData( x, y );
}

void QCustomParabola::showHead(bool visible)
{
    if ( visible == true ) {
        headLabel = new QCPItemText( plot );
        plot->addItem( headLabel );
        headLabel->position->setCoords( this->getHeadX(),
                                        this->getHeadY() - 2);
        headLabel->setText("[" + QString::number( this->getHeadX()  )
                           + ";" + QString::number( this->getHeadY() ) + "]");
    } else {
        delete headLabel;
    }
}

double QCustomParabola::getXMIN()
{
    return x_min;
}

double QCustomParabola::getXMAX()
{
    return x_max;
}

double QCustomParabola::getYMAX()
{
    return y_max;
}

double QCustomParabola::getYMIN()
{
    return y_min;
}

double QCustomParabola::getA()
{
    return a;
}

double QCustomParabola::getB()
{
    return b;
}

double QCustomParabola::getC()
{
    return c;
}

QString QCustomParabola::getName()
{
    return name;
}

double QCustomParabola::getHeadX()
{
    return ( -b/(2 * a) );
}

double QCustomParabola::getHeadY()
{
    return ( -getDiscriminant() / (4 * a) );
}

double QCustomParabola::getDiscriminant()
{
    return ( b * b - 4 * a * c );
}

QVector<double> QCustomParabola::getX()
{
    return x;
}

QVector<double> QCustomParabola::getY()
{
    return y;
}

QCPGraph *QCustomParabola::getGraph()
{
    return parabola;
}

QBrush QCustomParabola::getBrush()
{
    return brush;
}

QPen QCustomParabola::getPen()
{
    return pen;
}