Switching Form;

Hi all I'm relatively new at this qt programming so please bear with me :)

What I have been trying to do for hours now is close a login dialog and open a Mainwindow.

On the login Dialog i have a button. What i want is for this button to close the login Dialog (logindialog) and open the main form (userwindow). here's my code so far:

main.cpp:

Code:

---

#include <QtGui/QApplication>
#include "logindialog.h"
 
int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
    LoginDialog w;
    w.show();
 
    return a.exec();
}

---

logindialog.h:

Code:

---

#ifndef LOGINDIALOG_H
#define LOGINDIALOG_H
 
#include <QDialog>
 
namespace Ui {
    class LoginDialog;
}
 
class LoginDialog : public QDialog
{
    Q_OBJECT
 
public:
    explicit LoginDialog(QWidget *parent = 0);
    ~LoginDialog();
 
private:
    Ui::LoginDialog *ui;
 
private slots:
    void on_SubmitButton_clicked();
};
 
#endif // LOGINDIALOG_H

---

userwindow.h:

Code:

---

#ifndef USERWINDOW_H
#define USERWINDOW_H
 
#include <QMainWindow>
 
namespace Ui {
    class UserWindow;
}
 
class UserWindow : public QMainWindow
{
    Q_OBJECT
 
public:
    explicit UserWindow(QWidget *parent = 0);
    ~UserWindow();
 
private:
    Ui::UserWindow *ui;
};
 
#endif // USERWINDOW_H

---

logindialog.cpp:

Code:

---

#include "logindialog.h"
#include "ui_logindialog.h"
#include <QtGui>
 
using namespace std;
 
LoginDialog::LoginDialog(QWidget *parent) :
    QDialog(parent),
    ui(new Ui::LoginDialog)
{
    ui->setupUi(this);
}
 
LoginDialog::~LoginDialog()
{
    delete ui;
}
 
void LoginDialog::on_SubmitButton_clicked()
{
    /* Code is here for checking username and password 
        Want the userwindow to open and the logindialog to close */
 
 
 
}

---

userwindow.cpp:

Code:

---

#include "userwindow.h"
#include "ui_userwindow.h"
 
UserWindow::UserWindow(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::UserWindow)
{
    ui->setupUi(this);
}
 
UserWindow::~UserWindow()
{
    delete ui;
}

---

I have tried loads of different things from loads of different posts on loads of different forums. Perhaps i'm doing something fundamentally wrong :S Any code snippets would be greatly appreciated!!


Also on a side note, how come i have to use ui->label->settext() and most of the tutorials just use label->settext() ???

Thanks for your time and trouble. Much appreciated!! :)

hi,
u need to create obj for UserWindow in LoginDialog;
in LoginDialog.h

Code:

---

#ifndef LOGINDIALOG_H
#define LOGINDIALOG_H
 
#include <QDialog>
 
namespace Ui {
    class LoginDialog;
}
 
class LoginDialog : public QDialog
{
    Q_OBJECT
     UserWindow *u;
public:
    explicit LoginDialog(QWidget *parent = 0);
    ~LoginDialog();
 
private:
    Ui::LoginDialog *ui;
 
private slots:
    void on_SubmitButton_clicked();
};
 
#endif // LOGINDIALOG_H

---

and in LoginDialog.cpp

Code:

---

#include "logindialog.h"
#include "ui_logindialog.h"
#include <QtGui>
 
using namespace std;
 
LoginDialog::LoginDialog(QWidget *parent) :
    QDialog(parent),
    ui(new Ui::LoginDialog)
{
    ui->setupUi(this);
}
 
LoginDialog::~LoginDialog()
{
    delete ui;
}
 
void LoginDialog::on_SubmitButton_clicked()
{   
        this->close();            // close the logindialog
        u=new UserWindow;  //create obj for UserWindow
        u->show();    // open userwindow 
}

---

thats it.

and for

Quote:

---

Also on a side note, how come i have to use ui->label->settext() and most of the tutorials just use label->settext() ???

---

when you create the form using ui; you need to use ui->label->setText(); but when you design the form using coding then you need to give label->setText();

hope it helps
Bala

You could do either of these:

• Launch the dialog modally and then create a separate main window object and show() it (all in main()). Look at the QDialog::exec() rather than show() method to get a modal dialog.
  Code:

  ---

  #include <QtGui/QApplication>
  #include "logindialog.h"
   
  int main(int argc, char *argv[])
  {
      QApplication a(argc, argv);
      LoginDialog w;
      w.exec();
   
      MainWindow m;
      m.show();
   
      return a.exec();
  }

  ---

• Launch the main window object which immediately shows a modal login dialog. You could use a number of ways to get this to happen.

Really depends on your exact requirements.

Many Thanks to the both of you. I like the first solution more, as when I implement the second, the main form opens when the login form windows is closed, which is not ideal if you want some form of protection!!

Also thanks for the bit about why 'ui' needs to be used... Like i said I'm new at this and getting my head around everything is taking a bit of time. Thanks again :D

Just a quick question?

The line

Code:

---

UserWindow *u;

---

is this defining a variable? I'm confused! Thanks

I'm going to try my hand at answering this but just to test myself (I'm a newbie also :cool: ). Someone PLEASE correct me if I am wrong.

Code:

---

1.  UserWindow *u;

---

is a forward declaration of a pointer variable "u" of type UserWindow. It is a variable which is seen by the compiler as a pointer so a full declaration is not necessary in the header.

It is the declaration of a private member variable called "u" that is a pointer to an object of type UserWindow. The type UserWindow must be declared earlier in the file either in full or as a forward declaration (which is all that is required for a pointer). As far as I can see, the code in BalaQt's post does not contain the necessary declaration.

For this to compile you would need to add either:

Code:

---

// include the declaration of the UserWindow class
#include "userwindow.h"
OR
// a forward, incomplete declaration
class UserWindow;

---

near the top of LoginDialog.h (adjust the names as needed).

yes chris,

Quote:

---

As far as I can see, the code in BalaQt's post does not contain the necessary declaration.

---

i forget to add that. Thanks for pointing out. :)

@Splatify:
UserWindow *u; here you are declaring the objects for the class UserWindow.

Code:

---

void LoginDialog::on_SubmitButton_clicked()
{   
        this->close();            // close the logindialog
        UserWIndow *u=new UserWindow;  //u need to add UserWindow.h in the top of the cpp file.
        u->show();    // open userwindow 
}

---

if u declare inside a slot or a block of code, like above, the scope is within the block. (i.e) u cannot access this class variable outside the block. In your case, you can simply use this, since you dont need this obj outside the block.

but in some cases we may need a class obj or variable in our entire class functions or other class. In that case, we need to declare in the class declaration itself.

Splatify/ tnowacoski : I recommend you to read the oop concepts. without this Qt is not cute :)

pls go through the following link in your free time.
http://doc.qt.nokia.com/4.7-snapshot...-concepts.html
http://doc.qt.nokia.com/4.7-snapshot...practices.html

and pls read a good c++ book (c++ primer)

I found this link quiet useful, pls go through this
http://silmor.de/41

hope it helps,
Bala