Adding pixmap to scene* gives segfault

Akito_Kami

I have code to load from a filepath into a QGraphicsView, a image file as so:

void PDF::disp(QGraphicsView *view, QGraphicsScene *scene, const QString path)
{
    QImage image(path);
    QFile f(path);
    QGraphicsPixmapItem* item = new QGraphicsPixmapItem(QPixmap::fromImage(image));
    scene->addItem(item);
    view->setScene(scene);
    view->show();
 //   imageVector.push_back(scene);
}

In one of my projects, this works. In my current project, it gives me a segmentation fault. I have tried other methods to load the exact same image but also gives me a segementation fault.
My current usage example is

void PDF::on_pageListView_currentRowChanged(int index)
{
    QGraphicsScene* l;
    gen.removeAt(3);
    gen.insert(3, list.at(index));
    const QString i = gen.join("");
    disp(ui->leftView, l, i);
}

Other method that also gives a segfault:


void Reader::DisplayPages(QGraphicsScene *source, QGraphicsView *target, QString imgSrc) {
    if (!imgSrc.isEmpty()) {
        QPixmap pix = QPixmap(imgSrc);
        source->addPixmap(pix);
    }

    target->setScene(source);
    target->fitInView(target->sceneRect(), Qt::KeepAspectRatioByExpanding);
    target->verticalScrollBar()->setValue(0);
    target->show();
    imageVector.push_back(source);
}

jsulm

@Akito_Kami Here you did not create a QGraphicsScene instance, so you pass a dangling pointer to disp:

void PDF::on_pageListView_currentRowChanged(int index)
{
    QGraphicsScene* l; // new ...?
    gen.removeAt(3);
    gen.insert(3, list.at(index));
    const QString i = gen.join("");
    disp(ui->leftView, l, i); // l points to nowhere
}

Besides that you should first debug step by step to see where exactly it crashes.

Akito_Kami

@jsulm Thanks for the reply. On my other program, this didn't occur. So I was thinking that wouldn't be the case. It now works.