adding QGraphicsView to QBoxLayout - c++

Question

I am a QT newbie and trying to play around with Apps. I have just coded a very trivial App with some buttons. The main idea is to have a small "logo" in my App. LAter I would like to add some background image as well.
I have coded from an example App with a grid layout within which is a QBoxLayout which groups my buttons.
As you can see in my code, I have tried adding the Logo everywhere. When I added it in main.cpp, I have two views one showing buttons and the other my logo. Of course I do not want this. So I tried adding it in mainwindow.cpp but in this case, I don't see my Logo appearing anywhere at all :(
Please advise.
Here is the code:
main.cpp:
#include <QtGui/QApplication>
#include <QGraphicsScene>
#include <QGraphicsView>
#include <QGraphicsPixmapItem>
#include "mainwindow.h"
int main(int argc, char *argv[])
{
QApplication a(argc, argv);
Window window;
window.show();
/*
QGraphicsScene scene;
QGraphicsView view(&scene);
QGraphicsPixmapItem item(QPixmap("/home/marc/Desktop/Niranjana/Images/logo.9.png"));
scene.addItem(&item);
view.show();
*/
return a.exec();
}
mainwindow.h
#ifndef WINDOW_H
#define WINDOW_H
#include <QWidget>
#include <QRadioButton>
class QGroupBox;
class Window : public QWidget
{
Q_OBJECT
public:
Window(QWidget *parent = 0);
void onCheck_remote(int flag);
void onCheck_local(int flag);
private:
QRadioButton *button_local;
QRadioButton *button_remote;
QGroupBox *createPushButtonGroup();
};
#endif
mainwindow.cpp
#include <QtGui>
#include <QGraphicsScene>
#include <QGraphicsView>
#include <QGraphicsPixmapItem>
#include "mainwindow.h"
Window::Window(QWidget *parent)
: QWidget(parent)
{
QGridLayout *grid = new QGridLayout;
QGraphicsScene scene;
QGraphicsPixmapItem item(QPixmap("/home/test/logo.png"));
QGraphicsView view(&scene);
scene.addItem(&item);
view.show();
grid->addWidget(view.viewport(), 1, 1);
grid->addWidget(createPushButtonGroup(), 2, 1);
setLayout(grid);
setWindowTitle(tr("My App"));
resize(480, 420);
}
QGroupBox *Window::createPushButtonGroup()
{
QGroupBox *groupBox = new QGroupBox();
/*
QGraphicsScene scene;
QGraphicsPixmapItem item(QPixmap("/home/marc/Desktop/Niranjana/Images/logo.9.png"));
QGraphicsView view(&scene);
scene.addItem(&item);
scene.setBackgroundBrush(Qt::white);
view.show();
*/
QPushButton *button1 = new QPushButton(tr("&Start"));
QPushButton *button2 = new QPushButton(tr("&Stop"));
button_local = new QRadioButton(tr("&with power"));
button_remote = new QRadioButton(tr("without power"));
button_local->setChecked(1);
QVBoxLayout *vbox = new QVBoxLayout;
// vbox->addSpacing(10);
// vbox->addWidget(view.viewport());
//vbox->addSpacing(10);
vbox->addWidget(button1);
vbox->addSpacing(10);
vbox->addWidget(button2);
vbox->addSpacing(50);
vbox->addWidget(button_local);
vbox->addWidget(button_remote);
vbox->addStretch(1);
groupBox->setLayout(vbox);
return groupBox;
}

Answer 1

You should
Make your scene, view, item pointer members of your window class
Instantiate them in your Window ctor
do grid->addWidget(view, 1, 1);
Otherwise, all the items instantiated on the stack in the ctor will get deleted when exiting.