Load and display image in Qt GUI

Question

I work on Qt GUI C++ project. I try to display image from resource files, and there are more requirements like playing slideshow photos. I meet difficult when debugging, it just showed white screen. I thought the image was not loaded to GraphicsView. In in main.cpp and mainwindow.ui, I keep them like default, no editing. So please help me to fix this problem. Thanks in advance

mainwindow.cpp

#include "mainwindow.h"
#include "ui_mainwindow.h"
#include <QPixmap>
#include <QGraphicsPixmapItem>
#include <QMessageBox>
#include <QGraphicsView> 
#include <QStackedWidget>
#include <QGraphicsScene>
#include <QDataStream>
#include <QFile>

MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::MainWindow)
{
    ui->setupUi(this);
    QPixmap file(":/rose.jpg");
    QStackedWidget  *temp = new QStackedWidget();
    QGraphicsScene scene;
    QGraphicsView view(&scene);
        QGraphicsPixmapItem img(file);
        scene.addItem(&img);
        temp->addWidget(&view);
        setCentralWidget(view);
}

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

Answer 1

Your QGraphicsView and QGraphicsScene instance are local variable, they will be destroyed when out of the MainWindow constructor scope.

please try it like this.

QGraphicsScene *scene = new QGraphicsScene(this);
QGraphicsView *view = new QGraphicsView(scene);

If it still does't work, please check your QPixmap file is null or not just like what @Wagmare say.