Pass data between QWidgets

mandruk1331

I have a little problem, I have a Log_in window which connects to a server when a "Connect to Server" button is pressed, and when the connection is established I want to Register so I could LogIn, but in my new register window, I can't send the data because the Reg form does not contain the info about connection. Question: how I can pass an object(which contains the connection info) from the LogIn window, to the Reg form?

mrjj

Hi
Do you open the Reg.frm from login.form ?

mandruk1331

@mrjj Hello. Yes. Log_In form connects to the server (created a Communication Class), when I press the button, and I want to send the data from the Reg_form to the server, but I don't know how to do this, because the object which contains the connection info is in the Log_in form... I tried to use extern but no luck

mrjj

ok. extern is not a super good choice, you
can give also " Communication Class" to reg.form
when you construct it and show it.

I assume you have something like
Reg_form Reg(this);
Reg.exec() to show the Reg_form on button click

You could just add a public function in Reg.form
void SetComm( CommunicationClass *TheComm )
and let it store a internal pointer to it that u can use in its button click.

so u go something like
Reg_form Reg(this);
Reg->SetComm( TheCommunicationClass );
Reg.exec()
the TheCommunicationClass
should live as member variable in Log_In-form (in the .h file, in the class)
And be the one you do actually open/use. use & if its not a pointer.

It would be better to have CommunicationClass in mainwindow and let the dialogs sends signals to make main
perform the login/send etc. as using a pointer becomes clumsy if u say want to open yet another dialog but
can indeed work for 2.

mandruk1331

@mrjj And Now I want to copy the object stuff like this:
S_Cop is a Communication object which is in MRegForm. In the scope of the function it works good. But in other functions it loses all it's data
void MRegForm::A_obj(Com_Network &obj){
S_Cop = &obj;
}
The previous problem is solved. I was using the Signal/Slot mechanism. In LogIn form I create an instance of RegForm, and when in the LogIn form I connect to the server I emit a signal which will pass the object to the reg form... and it worked. Is it ok if i'll do it like this?
Code:
LogIn:
MLogIn::MLogIn(QWidget *parent) :
QMainWindow(parent),
ui(new Ui::MLogIn)
{
QObject::connect( this, SIGNAL( PassObject(Com_Network&)),&Regs, SLOT( A_obj(Com_Network&)));
ui->setupUi(this);
}
void MLogIn::on_Connect_S_clicked()
{
Conn.Initialize();
Conn.CreateSocket("127.0.0.1",'1400');
Conn.Connect();
emit PassObject(Conn);
}
RegForm:
void MRegForm::A_obj(Com_Network &obj){
qDebug()<<"Signal achieved";
qDebug()<<obj.i;
}

mrjj

@mandruk1331
hi
Good work :)
Yes it seems fine.

mandruk1331

@mrjj And Now I want to copy the object stuff like this:
S_Cop is a Communication object which is in MRegForm. In the scope of the function it works good. But in other functions it loses all it's data
void MRegForm::A_obj(Com_Network &obj){
S_Cop = &obj; // this one is OK!
qDebug()<<S_Cop.i; // i - is 9
}

void MRegForm::on_pushButton_clicked() //Register_button
{
qDebug()<<S_Cop.i; - is 0 // Not good. I think because it's out of scope. But I copied it in the previous slot, and the scope is the class, so it has to contain the data from the object I passed... but there is no data, dunno why
}

mrjj

@mandruk1331
Hi
Im not sure what Com_Network is. Is it your own class?

This statement could make copy of S_Cop if is not type (Com_Network *)
S_Cop = &obj;

For test, try with pointers in signal+slot instead of & reference.
so
emit PassObject( &Conn);
A_obj(Com_Network *obj)
Com_Network *S_Cop
Reference should have worked but since S_Cop seems bad in
on_pushButton_clicked, try with pointers and see if it makes difference.

mandruk1331

@mrjj Com_Network is my own class which I use for Communication between Client and Server. Ok, I will give it a try.

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Pass data between QWidgets