graphicsView->setScene causes SIGSEGV

micha_eleric

#include <QApplication>
#include <QCoreApplication>
#include <QDebug>
#include <QtGui>
#include <QMainWindow>
#include <QSerialPort>
#include <QThread>
#include <cstring>
#include <fstream>
#include <functional>
#include <iostream>
#include <sstream>
#include <string>
#include "Ui_MainWindow.h"
Ui_MainWindow *m_ui;
QGraphicsScene * m_GScene;
m_GScene = new QGraphicsScene();
m_ui->graphicsView->setScene(m_GScene);

?graphicsView->setScene causes SIGSEGV?

not sure where i got graphicsView->setScene

what is causing SIGSEGV? how to fix?

micha_eleric

order
it was the order
m_ui got assigned after m_ui got called.

JoeCFD

This may not crash. But you know if m_ui and m_ui->graphicsView are defined.

Ui_MainWindow *m_ui;
auto m_GScene = new QGraphicsScene;
if ( nullptr != m_ui && nullptr != m_ui->graphicsView ) {
    m_ui->graphicsView->setScene(m_GScene);
}

micha_eleric

#include <QApplication>

#include <QGraphicsView>
#include <QGraphicsScene>
#include <QPointF>
#include <QVector>

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
    QVector <QPointF> points;

    // Fill in points with n number of points
    for(int i = 0; i< 100; i++)
       points.append(QPointF(i*5, i*5));

    // Create a view, put a scene in it and add tiny circles
    // in the scene
    QGraphicsView * view = new QGraphicsView();
    QGraphicsScene * scene = new QGraphicsScene();
    view->setScene(scene);

    for(int i = 0; i< points.size(); i++)
        scene->addEllipse(points[i].x(), points[i].y(), 1, 1);

    // Show the view
    view->show();

    // or add the view to the layout inside another widget

    return a.exec();
}

this is from stackoverflow, and runs
what is based my code bit on

JoeCFD

show more of your code if you want to be helped.

micha_eleric

@JoeCFD said in graphicsView->setScene causes SIGSEGV:

show more of your code if you want to be helped.

ok. i included the include files

micha_eleric

order
it was the order
m_ui got assigned after m_ui got called.