how to update widgets in a tabwidget

Mark58

Hi
I have a tabwidget within my mainwindow. The tabwidget has a QLabel which should be changed. In the mainwindow I have a QLineEdit and a QPushbutton. When I enter a text in the QLineEdit und press the button, the label in the tabwidget should get the value of the lineedit.
The ui of the tabwidget with the QLabel is in a seperate file.
However, the QLabel does not change. Signal/Slot is working, because "qDebug" prints "hallo".

my mainwindow.h:

#ifndef MAINWINDOW_H
#define MAINWINDOW_H

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

QT_BEGIN_NAMESPACE
namespace Ui { class MainWindow; }
QT_END_NAMESPACE

class MainWindow : public QMainWindow
{
    Q_OBJECT

public:
    MainWindow(QWidget *parent = nullptr);
    ~MainWindow();

signals:
    void sendmessage(QString);

private slots:
    void on_pushButton_clicked();

private:
    Ui::MainWindow *ui;
    tab_todo mydo;
};
#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);

    ui->tabWidget->addTab(new tab_todo, "Action_here");

    connect(this, SIGNAL(sendmessage(QString)),&mydo,SLOT(receiver(QString)));

}

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


void MainWindow::on_pushButton_clicked()
{
    QString messagetext = ui->lineEdit->text();
    sendmessage(messagetext);
}

tab_to.h

#ifndef TAB_TODO_H
#define TAB_TODO_H

#include <QWidget>
#include <QDebug>

namespace Ui {
class tab_todo;
}

class tab_todo : public QWidget
{
    Q_OBJECT

public:
    explicit tab_todo(QWidget *parent = nullptr);
    ~tab_todo();


private slots:
    void receiver(QString message);


private:
    Ui::tab_todo *ui;
};

#endif // TAB_TODO_H

tab_todo.cpp

#include "tab_todo.h"
#include "ui_tab_todo.h"

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

}

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

void tab_todo::receiver(QString message)
{
    qDebug() << "now at receiver" << "message:" << message;
    ui->label->setText(message);
}

Thanks for your help.

mrjj

Hi
Adding to @SGaist good points.

The reason the text is not changing is that you have 2 of them

tab_todo mydo; <<< in .h instance 1

//  here you create a new one and not use the one from .h
    ui->tabWidget->addTab(new tab_todo, "Action_here");  

// then connect to the one from .h that is not shown on screen.
 connect(this, SIGNAL(sendmessage(QString)),&mydo,SLOT(receiver(QString)));

SGaist

Hi,

Give your tab_todo class the proper API to do that. Your MainWindow should not care where the text is shown. It should just set it on that widget and that one is responsible to forward it where appropriate.

mrjj

Hi
Adding to @SGaist good points.

The reason the text is not changing is that you have 2 of them

tab_todo mydo; <<< in .h instance 1

//  here you create a new one and not use the one from .h
    ui->tabWidget->addTab(new tab_todo, "Action_here");  

// then connect to the one from .h that is not shown on screen.
 connect(this, SIGNAL(sendmessage(QString)),&mydo,SLOT(receiver(QString)));

Mark58

@mrjj Thank you
Your answer was helpful and understandable.
I changed the .h - file to:

ui->tabWidget->addTab(&mydo, "Action_here");

and it works.