Why numerator function doesn't work?

[ddryomyss]

This program should add enumerated points on screen on every left button press. Points are ellipses painted on the scene, numbering should be done by new labels creation.

mainwindow.h:

#ifndef MAINWINDOW_H
#define MAINWINDOW_H

#include <QMainWindow>
#include <QLabel>
#include <QTimer>
#include <QResizeEvent>

#include <paintscene.h>


//QT_BEGIN_NAMESPACE
namespace Ui { class MainWindow; }
//QT_END_NAMESPACE

class MainWindow : public QMainWindow
{
    Q_OBJECT

public:
    explicit MainWindow(QWidget *parent = nullptr);
    ~MainWindow();

    void numerator(int num, qreal x, qreal y);

private:
    Ui::MainWindow *ui;
    QTimer *timer;
    paintScene *scene;

    void resizeEvent(QResizeEvent * event);


    int j = 1;
    bool ind = true;


private slots:
    void slotTimer();

};

#endif // MAINWINDOW_H

mainwindow.cpp:

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

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

    scene = new paintScene();
    ui->graphicsView->setScene(scene);

    timer = new QTimer();
    connect(timer, &QTimer::timeout, this, &MainWindow::slotTimer);
    timer->start(100);
}

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

void MainWindow::numerator(int num, qreal x, qreal y)
{
    QLabel *label = new QLabel(this);
    label->setText(QString("%1").arg(num));
    label->setGeometry(x+10,y-20,20,20);
    label->show();
}

void MainWindow::slotTimer()
{
    timer->stop();
    scene->setSceneRect(0,0, ui->graphicsView->width() - 20, ui->graphicsView->height() - 20);
}


void MainWindow::resizeEvent(QResizeEvent *event)
{
    timer->start(100);
    QWidget::resizeEvent(event);
}

paintscene.h

#ifndef PAINTSCENE_H
#define PAINTSCENE_H

#include <QGraphicsScene>
#include <QGraphicsSceneMouseEvent>
#include <QTimer>

#include <QLabel>

class paintScene : public QGraphicsScene
{

    Q_OBJECT

public:
    paintScene(QObject *parent = 0);
    ~paintScene();

    void addPoint(qreal x, qreal y);

private:
    void mousePressEvent(QGraphicsSceneMouseEvent * event);


    QVector<qreal> coord_x, coord_y, distances;
    bool ind = true;
    const qreal rad = 5.0;
    qreal last_pt_x, last_pt_y;
    int i = 1;


};

#endif // PAINTSCENE_H

paintscene.cpp

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

//#include <QLabel>

paintScene::paintScene(QObject *parent) : QGraphicsScene(parent)
{
    
}

paintScene::~paintScene()
{

}

void paintScene::addPoint(qreal x, qreal y)
{
    coord_x.push_back(x);
    coord_y.push_back(y);
}

void paintScene::mousePressEvent(QGraphicsSceneMouseEvent *event)
{
    MainWindow mw;
    if (event->button() == Qt::LeftButton && ind == true)
        {
        addEllipse(event->scenePos().x() - rad,
                   event->scenePos().y() - rad,
                   2*rad,
                   2*rad,
                   QPen(Qt::NoPen),
                   QBrush(Qt::red));
        mw.numerator(i,event->scenePos().x(), event->scenePos().y());
        ++i;
        addPoint(event->scenePos().x(), event->scenePos().y());

        }
    else if (event->button() == Qt::RightButton && ind == true)
        {
        addEllipse(event->scenePos().x() - rad,
                   event->scenePos().y() - rad,
                   2*rad,
                   2*rad,
                   QPen(Qt::NoPen),
                   QBrush(Qt::black));
        ind = false;
        last_pt_x = event->scenePos().x();
        last_pt_y = event->scenePos().y();
    }
}

[J.Hilk]

@ddryomyss said in Why numerator function doesn't work?:

please read up on the c++ basics, about object instances, scopes, heap and stack

because this

void paintScene::mousePressEvent(QGraphicsSceneMouseEvent *event)
{
MainWindow mw;

is != to

to the MainWindow that you have inside main.cpp and that you actually show.