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.