Qt menubar disappears when I use scroll area

[Sai Kamat]

I want to implement a vertical scroll bar. I have implemented layouts for this(see the attached layouts.jpg), and also scroll area(see snippet in below code). Yet, when I run, the window does not have menubar. What am I missing here? I tried adding the menubar and submenus through Qt designer, as well as through code, but the window does not show the menubar.

If i use scroll area snippet, i can use the scrollbar, but don't see menubar. However If i comment out the scroll area snippet, i can see the menubar, but lose the scroll bar. I need both of them. How to solve this?

"Your text to link here...":http://i.stack.imgur.com/Nj9OG.jpg

Here is the code:-
mainwindow.h
@#ifndef MAINWINDOW_H
#define MAINWINDOW_H

#include <QMainWindow>
#include <QScrollArea>
namespace Ui {
class MainWindow;
}

class MainWindow : public QMainWindow
{
Q_OBJECT

public:
explicit MainWindow(QWidget *parent = 0);
~MainWindow();

private:
Ui::MainWindow *ui;

};

#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);
layout()->setMenuBar(menuBar());
QMenu *viewMenu;
viewMenu = menuBar()->addMenu("VIEW");
QMenu *resolutionSubMenu = viewMenu->addMenu("Resolution");
QAction *QVGA = resolutionSubMenu->addAction("QVGA");

QImage image(":\\image.jpg");
ui->referenceImageLabel->setPixmap(QPixmap::fromImage(image));
ui->deltaImageLabel->setPixmap(QPixmap::fromImage(image));
ui->reconstructedImageLabel->setPixmap(QPixmap::fromImage(image));
ui->referenceImageLabel->setMinimumSize(480, 640);ui->referenceImageLabel->setMinimumSize(480, 640);ui->referenceImageLabel->setMinimumSize(480, 640);

/*Scroll area snippet*/
QScrollArea *p_ScrollArea = new QScrollArea(this);
p_ScrollArea->setAutoFillBackground(true);
p_ScrollArea->setMinimumSize(width(), height());
p_ScrollArea->setWidget(ui->centralWidget);

}

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

main.cpp
@
#include "mainwindow.h"
#include <QApplication>

int main(int argc, char *argv[])
{
QApplication a(argc, argv);
MainWindow w;
w.show();

return a.exec();

}@

[SGaist]

Hi,

Why ?

@layout()->setMenuBar(menuBar());@

The menu bar is already put at the right place for you when you use a QMainWindow

@
QScrollArea *p_ScrollArea = new QScrollArea(this);
p_ScrollArea->setAutoFillBackground(true);
p_ScrollArea->setMinimumSize(width(), height());
p_ScrollArea->setWidget(ui->centralWidget);
@

You scroll area is just floating.

Since you already use Designer to create your UI, why don't you also setup the scroll area and menus there ?

[Sai Kamat]

Hi SGaist,
For the 1st question, when i added menubar through the designer, and run the program, the menubar was not there. so i added the line programmatically, but that did not help either.

For the 2nd question, i do not know how to implement scroll bar for three qlabels through designer mode. If you have a tutorial where multiple qlables can be scrolled using a single vertical or horizontal scrollbar, through designer mode, and can share, i'd be most grateful.

Also, what's a floating scroll area?

[SGaist]

The first thing you should do is have a look at Qt's example and tutorials you should then be able to create your widget.

It's floating in the sense that you didn't set it as central widget nor in a layout thus you have to handle it's size and position by hand.