How to set property of button to visible from widget in Qt

Question

I have one window which includes all the buttons and there are some buttons that are hidden.

Now I want set visibility to true from another dialog.

How to do it? I have googled it but I am unable to solve this problem.

#include "mainwindow.h"
#include "ui_mainwindow.h"
#include "rams.h"
#include "abtdev.h"
#include "syllabus.h"
#include "login.h"

MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::MainWindow)
{
    ui->setupUi(this);
    setWindowFlags(Qt::Window | Qt::FramelessWindowHint);
    QMainWindow::showFullScreen();

    **ui->but_save->setHidden(true);
    ui->but_delete1->setHidden(true);
    ui->but_delete2->setHidden(true);
    ui->but_upload1->setHidden(true);
    ui->but_upload2->setHidden(true);**
}

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

void MainWindow::on_but_abt_clicked()
{
    abtdev a;
    a.exec();
}

void MainWindow::on_but_Syllabus_clicked()
{
    syllabus s;
    s.showFullScreen();
    s.exec();
}

void MainWindow::on_but_admin_clicked()
{
    login objlogin;
    objlogin.exec();
}

void MainWindow::on_but_rams_clicked()
{
    // rams ramswin;
    // ramswin.showFullScreen();
    // ramswin.exec();
}

And I want it appear after this dialog box get completed!

#include "login.h"
#include "ui_login.h"
#include<QTimer>
#include "mainwindow.h"
#include "ui_mainwindow.h"
#include<QObject>

login::login(QWidget *parent) :
    QDialog(parent),
    ui(new Ui::login)
{
    ui->setupUi(this);
    setWindowFlags(Qt::Window | Qt::FramelessWindowHint);
    QTimer::singleShot(60000, this, SLOT(close()));
    ui->password->setEchoMode(QLineEdit::Password);
}

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

void login::on_ok_clicked()
{
    QString username = ui->username->text();
        QString password = ui->password->text();

        if(username ==  "123" && password == "123")
        {


       ***HERE, after this block executed i want that buttons visible on mainwindow***

          }
        else
        {
            ui->label_4->setText("Username and password is not correct !!");
        }
}

Answer 1

The code you need is next:

Supposing that you call your dialog for example from MainWindow::on_but_admin_clicked() function:

On mainwindow.cpp

void MainWindow::on_but_admin_clicked()
{
    //Declare a private object in your mainwindow.h like this:
    //login* objlogin; 
    objlogin = new login();
    //Connect signals to later call the method setHiden(false)
    QObject::connect(objlogin, SIGNAL(stackoverflowAnswer()), this, SLOT(makeVisible()));
    objlogin->show();
}

//...
// The function that will be called from login dialog to enable hidden buttons
void MainWindow::makeVisible()
{
    ui->but_save->setHidden(false);
    ui->but_delete1->setHidden(false);
    ui->but_delete2->setHidden(false);
    ui->but_upload1->setHidden(false);
    ui->but_upload2->setHidden(false);
}

On login.cpp (on_ok_clicked() function):

void login::on_ok_clicked()
{
    QString username = ui->username->text();
        QString password = ui->password->text();

        if(username ==  "123" && password == "123")
        {


       ***HERE, after this block executed i want that buttons visible on mainwindow***

            emit stackoverflowAnswer();
            //...

Remember to declare in login.h the signals and slots:

signals:
    void stackoverflowAnswer();
private slots:
    void on_ok_clicked();