How to use Qt classes defined accross multiple files?

MakingTheEight

I'm trying to create my first Qt desktop application. I have managed to create a QMainWindow widget and I am trying to add a menu bar to it. I was able to create a MainWindow with a menu bar that has one menu option. I was able to do this when all my code was in one file, and I was using the MainWindow constructor to set up the whole GUI.

I now would like to separate my GUI/widgets into separate files for maintainability.
Here are my current files:
mainwindow.h

#ifndef MAINWINDOW_H
#define MAINWINDOW_H

#include <QMainWindow>
#include "filesystem.h"

#include "./menu/filemenu.h"

class QString;

class FileMenu;

namespace Ui {
class MainWindow;
}

class MainWindow : public QMainWindow {
    Q_OBJECT

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

    ~MainWindow();

private:
    Ui::MainWindow *ui;
    QString main_title = "";

    int width;
    int height;

    FileMenu *filemenu;

    void setName() {
        this->setWindowTitle(MainWindow::main_title);
    };

    void resizeMainWindow();
    void setUp();

    // void createMenuBar();


};

#endif

mainwindow.cpp

#include <stdlib.h>
#include <QtWidgets>
#include "mainwindow.h"
#include "ui_mainwindow.h"
#include <QDesktopWidget>
#include <QRect>



MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent), ui(new Ui::MainWindow) {
    ui->setupUi(this);
    this->setUp();
    filemenu = new FileMenu(this);
    filemenu->createMenuBar();
}

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

void MainWindow::resizeMainWindow() {
    QRect main_screen = 
   QDesktopWidget().availableGeometry(QDesktopWidget().primaryScreen());
    MainWindow::height = main_screen.height();
    MainWindow::width = main_screen.width();
    this->resize(MainWindow::width, MainWindow::height);
}

void MainWindow::setUp() {
    this->setName();
    this->resizeMainWindow();
}

./menu/filemenu.h

#ifndef FILEMENU_H
#define FILEMENU_H

#include <QMenu>
#include <QAction>
#include <QMenuBar>

#include "../mainwindow.h"

class MainWindow;
class QMenu;
class QMenuBar;

class FileMenu: public QMainWindow {
    Q_OBJECT

    public:
        FileMenu(MainWindow *p);
        ~FileMenu();
        void createMenuBar();

    private:
        MainWindow *parent;

        QMenu *fileOption;
        QAction *newFolder;
        QAction *newFile;
        QAction *newWindow;
        QAction *exitWindow;

        void createFileActions();
    private slots:
        void openNewFolder();
        void openNewWindow();
        void openNewFile();
        void exitWindow();
};

#endif

./menu/filemenu.cpp

#include "filemenu.h"
#include <QMainWindow>

FileMenu::FileMenu(MainWindow *p):
    parent(p) {
    //this->createMenuBar();
    this->createFileActions();

}

void FileMenu::createMenuBar() {
    fileOption = menuBar()->addMenu(tr("&File"));
    fileOption->addAction(newWindow);
    fileOption->addAction(newFolder);
    fileOption->addAction(newFile);
}


void FileMenu::createFileActions() {
    newFolder = new QAction(tr("&New Folder"), this);
    newFolder->setShortcut(tr("Ctrl+Shift+N"));
    newFolder->setStatusTip(tr("Create a new folder"));
    connect(newFolder, &QAction::triggered, this, &FileMenu::openNewFolder);

    newWindow = new QAction(tr("&New Window"), this);
    newWindow->setShortcut(tr("Ctrl+N"));
    newWindow->setStatusTip("Open a new MTX window");
    connect(newWindow,&QAction::triggered, this, &FileMenu::openNewWindow);

    newFile = new QAction(tr("&New File"), this);
    newFile->setShortcut(tr("Shift+N"));
    newFile->setStatusTip("Create a new file");
    connect(newFile, &QAction::triggered, this, &FileMenu::openNewFile);

    exitWindow = new QAction(tr("&Exit"), this);
    exitWindow->setShortcut(tr("Shift+C"));
    exitWindow->setStatusTip("Exit MTX");
    connect(exitWindow, &QAction::triggered, this, &FileMenu::openNewFile);
}
void FileMenu::exitWindow() {
    exit(EXIT_SUCCESS);
}


FileMenu::~FileMenu() {
    delete newFolder;
    delete newFile;
    delete newWindow;
    delete exitWindow;
}

However, when I make and run the project when it's structured as above, the main window loads with no menu. What am I doing wrong?

Thanks for the help.

SGaist

Hi and welcome to devnet,

Because you're not looking at the main window you expect. You did not really separate things here actually, you created a separate QMainWindow based class that you put in the main QMainWindow based class but you don't show it.

MakingTheEight

@SGaist Can you expound on this statement? I'm not sure I understand it exactly as you've phrased it.

You did not really separate things here actually, you created a separate QMainWindow based class that you put in the main QMainWindow based class but you don't show it.

Thanks.

mrjj

@MakingTheEight
Hi
In the old Mainwindow, you do

MainWindow::MainWindow(QWidget *parent) :
QMainWindow(parent), ui(new Ui::MainWindow) {
ui->setupUi(this);
this->setUp();
filemenu = new FileMenu(this); // new main window
filemenu->createMenuBar();
}

But you do not see FileMenu, but the MainWindow ( i assume).

Please try 

filemenu = new FileMenu(); // new main window dont give parent
filemenu->createMenuBar();
filemenu->show();

You should see you actually have 2 MainWindows :)

I assume you want to use FileMenu as the new MainWindow ?

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
    a.setStyleSheet( yourstylesheet );
    MainWindow w; // use FileMenu here instead
    w.show();

    return a.exec();
}

jsulm

@MakingTheEight

class MainWindow : public QMainWindow {
...
class FileMenu: public QMainWindow {

Do you realise that you create TWO QMainWindows?
Why is FileMenu derived from QMainWindow?

MakingTheEight

@jsulm I have tried to have FileMenu inherit from QMenu but I get the following error.
error: ‘menuBar’ was not declared in this scope.

My idea was to have FileMenu inherit QMenu from QMainWindow. How would you suggest I solve my problem.

Thanks for the hel

SGaist

Remove the use of menuBar from it and pass the FileMenu instance to your MainWindow status bar.

MakingTheEight

@jsulm @mrjj @ig Thanks for all the help.
I was able to fix the inheritance issue by creating a new FileMenu instance in the main window.