#include "mainwindow.h"
#include "ui_mainwindow.h"

#include <QtCharts/QChartView>
#include <QtCharts/QLineSeries>
#include <QtCharts/QValueAxis>

QT_CHARTS_USE_NAMESPACE

MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::MainWindow)
{
    ui->setupUi(this);

    const int count = 1495;

    //if set series->setUseOpenGL(true);
    //const double _xmin(17249.999500); //don't show chart
    //const double _xmax(17250.000500); //don't show chart
    const double _xmin(17249.999500); //stairs
    const double _xmax(17250.015500); //stairs
    //const double _xmin(17000.999500); //work very well
    //const double _xmax(17500.000500); //work very well

    const double _ymin(4.0);
    const double _ymax(8.0);
    double _xstep((_xmax-_xmin)/count);
    double _ystep((_ymax-_ymin)/count);

    QValueAxis* _axisX = new QValueAxis;
    QValueAxis* _axisY = new QValueAxis;
    _axisX->setRange(_xmin, _xmax);
    _axisY->setRange(_ymin, _ymax);

//![1]
    QLineSeries *series = new QLineSeries();
//![1]

    connect(series, SIGNAL(useOpenGlChanged()), this, SLOT(doUseOpenGlChanged()));

    for(int i=0; i<count; i++) {
        series->append(_xmin + _xstep*i, _ymin + _ystep*i);
    }
    series->setUseOpenGL(true);
    bool useOpenGL = series->useOpenGL();

//![2]
    //series->append(0, 6);
    //series->append(2, 4);
    //series->append(3, 8);
    //series->append(7, 4);
    //series->append(10, 5);
    //*series << QPointF(11, 1) << QPointF(13, 3) << QPointF(17, 6) << QPointF(18, 3) << QPointF(20, 2);
//![2]

//![3]
    QChart *chart = new QChart();

    chart->legend()->hide();
    chart->addSeries(series);
    chart->createDefaultAxes();
    chart->setTitle("Simple line chart example");
//![3]

    chart->setAxisX(_axisX, series);
    chart->setAxisY(_axisY, series);

//![4]
    QChartView *chartView = new QChartView(chart);
    chartView->setRenderHint(QPainter::Antialiasing);
//![4]

    this->setCentralWidget(chartView);
    this->resize(600, 400);
    //this->show();

}

MainWindow::~MainWindow()
{
    delete ui;
}

void MainWindow::doUseOpenGlChanged(void)
{
    QMessageBox msgBox;
    msgBox.setText("signal useOpenGlChanged");
    msgBox.exec();
}

//I can see on help -  https://doc.qt.io/qt-5/qabstractseries.html#useOpenGL-prop
//Signals...
//void	useOpenGLChanged()
//but when I run the application I've got the message
//QObject::connect: No such signal QtCharts::QLineSeries::useOpenGlChanged()