Tab creation in Qt

Question

I wanted to create a new tab dynamically when a button is clicked in the mainwindow.Let this button be NEW. I have placed a QWidget in the mainwindow where I would like the QTabWidget to be visible. I have added a new form with class named TabWidget (QTabWidget) containing my 1st page design.

I did this:

page1 = new TabWidget(ui->widget);  // TabWidget inherits QTabWidget
this->centralWidget()->layout()->addWidget(page1);

Got the 1st page in my QWidget. This is done.

I tried to implement traversing from one tab to other using BACK and NEXT button.

I designed the 2nd tab in a widget (named form2) instead of a QTabWidget and I called this form from my 1st tab using:

page2 = new Form2();   // Form2 contains the tab2 design
TabWidget::addTab(page2,"Scalar Parameters");  // Only this works, I couldn't use objects
TabWidget::setCurrentWidget(page2);

Here comes the problem:
I could not do the same thing for the 3rd tab.

page3 = new Form3();  // Form3 contains the tab3 design
TabWidget *t= new TabWidget();
t->addTab(page3,"Table Parameters");
t->setCurrentWidget(page3);

What am I missing here?

I have these files,

mainframe.h, tabwidget.h (inherits QTabWidget) This is also my 1st tab, tabwidget2.h (inherits QWidget) 2nd tab, tabwidget3.h (inherits QWidget) 3rd tab.

I have included tabwidget.h in mainframe.h and created an object for it, page1. So when a button is clicked on the mainframe, i do this,

TabWidget *page1 = new TabWidget();
this->centralWidget()->layout()->addWidget(page1);

This creates a Tab with my design on the mainframe. This works perfectly. Then I have a NEXT button in this tab page1.So when I click it, I want to add a new tab page2 to this pag1. For this I included tabwidget2.h in tabwidget.h and created an object page2. Now when a button is clicked in my page1, I do this,

tabwidget2 *page2 = new tabwidget2();
tabwidget *t= new tabwidget();
t->addTab(page2,"Scalar Parameters");
t->setCurrentWidget(page2);

But this doesn't work. So I did this,

tabwidget2 *page2 = new tabwidget2(t);
tabwidget::addTab(page2,"Scalar Parameters");
tabwidget::setCurrentWidget(page2);

This worked and I got the 2nd page added to my 1st tab. The problem arises when I add the 3rd page when a NEXT button is clicked from the page2. I did this,

tabwidget3 *page3 = new tabwidget3();
tabWidget *t= new tabWidget();
t->addTab(page3,"Table Parameters");
t->setCurrentWidget(page3);

and didn't work. Program compiles without any error. Mainframe -> (New button) -> page1( which is a QTabWidget displays on Widget on mainframe) -> (NEXT button) -> page2 ( QWidget added as a new tab to page1) -> (NEXT button ) -> nothing happens

I have tried my Best to explain this. Please Help me out.

Code: mainframe.h

#ifndef MAINWINDOW_H
#define MAINWINDOW_H

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


namespace Ui {
class MainWindow;
}

class MainWindow : public QMainWindow
{
    Q_OBJECT

public:
    explicit MainWindow(QWidget *parent = 0);
    TabWidget *page1;
    ~MainWindow();

private slots:
     void on_action_About_triggered();

     void on_action_New_triggered();

private:
     Ui::MainWindow *ui;
};

Tabwidget.h

#ifndef TABWIDGET_H
#define TABWIDGET_H

#include <QTabWidget>
#include "tabwidget2.h"

namespace Ui {
class TabWidget;
}

class TabWidget : public QTabWidget
{
     Q_OBJECT

public:
    explicit TabWidget(QWidget *parent = 0);
    ~TabWidget();
    tabwidget2 *page2;

private slots:
    void on_pushButton_6_clicked();

private:
    Ui::TabWidget *ui;
};

#endif // TABWIDGET_H

tabwidget2.h

#ifndef TABWIDGET2_H
#define TABWIDGET2_H

#include <QWidget>
#include "tabwidget3.h"


namespace Ui {
class tabwidget2;
}

class tabwidget2 : public QWidget
{
   Q_OBJECT

public:
   explicit tabwidget2(QWidget *parent = 0);
   ~tabwidget2();
   tabwidget3 *page3;

private slots:
   void on_pushButton_2_clicked();

private:
   Ui::tabwidget2 *ui;
};

#endif // TABWIDGET2_H

mainframe.cpp

#include "mainwindow.h"
#include "ui_mainwindow.h"
#include "QtWidgets"
#include "qtabwidget.h"
#include "qdialog.h"

MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::MainWindow)
{
     ui->setupUi(this);
}

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

void MainWindow::on_action_New_triggered()
{
   TabWidget *page1 = new TabWidget();
   this->centralWidget()->layout()->addWidget(page1);
}

tabwidget.cpp

#include "tabwidget.h"
#include "ui_tabwidget.h"

TabWidget::TabWidget(QWidget *parent) :
  QTabWidget(parent),
  ui(new Ui::TabWidget)
{
    ui->setupUi(this);
 }

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

void TabWidget::on_pushButton_6_clicked()
{
    tabwidget2 *page2 = new tabwidget2();
    this->addTab(page2,"Scalar Parameters");
    this->setCurrentWidget(page2);
 }

tabwidget2.cpp

#include "tabwidget2.h"
#include "ui_tabwidget2.h"
#include "tabwidget.h"

tabwidget2::tabwidget2(QWidget *parent) :
QWidget(parent),
ui(new Ui::tabwidget2)
{
    ui->setupUi(this);
}

tabwidget2::~tabwidget2()
{
    delete ui;
}

void tabwidget2::on_pushButton_2_clicked()
{

    tabwidget3 *page3 = new tabwidget3();
    TabWidget *t= new TabWidget();
    t->addTab(page3,"Table Parameters");
    t->setCurrentWidget(page3);
}

I just cant bring in my page3.

Answer 1

You have some errors in your code. This is the way you would add tabs to QTabWidget

QTabWidget *tabwidget = new QTabWidget(ui->centralWidget);
tabwidget->setObjectName(QString("tabbar"));

QWidget *tab = new QWidget();
tabwidget->addTab(tab, "tab1");

QWidget *tab2 = new QWidget();
tabwidget->addTab(tab2, "tab2");
tabwidget->setCurrentWidget(tab2);
// etc.

So in your case it will probably be:

page1 = new TabWidget(ui->centralWidget);

page2 = new Form2();
page1->addTab(page2, "Scalar Parameters");
page1->setCurrentWidget(page2);

page3 = new Form3();
page1->addTab(page3, "Table Parameters");
page1->setCurrentWidget(page3);

You have to add tabs (your Form classes) to the QTabWidget which means adding them to page1 object.

If you want to add Tabs from a place where you can't access page1, I'd add ObjectName to page1 so that you can search it later.

TabWidget *page1 = new TabWidget();
this->centralWidget()->layout()->addWidget(page1);
page1->setObjectName("TabWidget"); //name it whatever you want

And then when adding new Tab do:

tabwidget3 *page = new tabwidget3()
TabWidget *temporary = ui->centralWidget->findChild<TabWidget *>("TabWidget");
temporary->addTab(page3, "name");
temoprary->setCurrentWidget(page3);

Don't create new TabWidget. QTabWidget is like a container for tabs, if you want to add a tab you have to add it to and existing one.