how to modify mainform.ui components from other form, and vice versa

Cuban Akira

i pass like a hour reading online about signals and slot in QT, is amazing,
with this code y can manipulate behaviors on the same form
ex. connect(ui->pushButton,SIGNAL(clicked(bool)),ui->comboBox, SLOT (hide()));
but, working with objects placed in diferent forms i dont know how to reference it
ex. this dont work>
connect(ui->pushButton,SIGNAL(clicked(bool)),Form2.ui->comboBox, SLOT (hide()));
cant reference objects from other forms

mrjj

@Cuban-Akira
Hi
Instead of surfacing all the widgets from form2, you would add access slot function to be triggered from out
side. the slot it self , will then ask the UI elements directly.

So for Form2, you would add
public slots:
void HideSomething() {
ui->button->hide();
}

and from form1, you connect to buttons clicked() to HideSomething()

that way, form1 do not have know every widget that form2 has -
but can use an interface to carry out
any needed call to the actual widgets in form2.
This a better design versus making UI public.

this example seems a bit silly to hide a button and not its something you would need very often.
However, imagine you had a form2, with a lineEdit.
From form1, yo want a persons name to be put in that lineEdit.
Then you add a new slot called
void setName(QString name) {
ui->lineEdit->setText(name);
}

and use that from form1 to make it display name.
Say you later found out, you want to show name in a QLabel.
All you need is to change setName slot to use this label, but
rest of the code will work unmodified as form1, only knows
setName, not that it was an lineEdit in form2.

So this make application far more robust as small changes wont
change how rest of the program uses form2.
Rest of program , only knows the interface for displaying data you defined.
Not how its was build internally.
I hope this makes sense :)

Cuban Akira

@mrjj
i understand your point, but still have errors on my code
after create the signals and slot, i dont know how to write the 3rd argument in connect funtion

connect(ui->pushButton, SIGNAL (click()) , information , SLOT(hideEditar()));

the 3rd parameter (the name of the 2nd form, "information") is wrong,
if i create> information *info= new information();, and putt "info" as the 3rd argument of connect the program launch an exeption, and stop

mrjj

@Cuban-Akira
hi
"information" needs to be a pointer to a class instance. not classname.
So if forms Type/Class is Information
then
information *info= new information(this); // make instance of information form
connect(ui->pushButton, SIGNAL (click()) , info, SLOT(hideEditar()));

Cuban Akira

@mrjj
thanks a lot men, but i dont know what happens
when i put
informacion *info = new informacion(this);

connect(ui->pushButton, SIGNAL (click()) , info , SLOT(hideEditar()));

the app stop, says, > crashed

mrjj

@Cuban-Akira
Hi
Sounds like it crashes.
Can you show the actual code ?
The connect seems fine so its just something else.

can it be in hideEditar it crashes ?

Can it be you fun this code BEFORE the setupUI() in form1 ?

Cuban Akira

@mrjj

i think the mistake is in " informacion *info = new informacion(this);"
cause "this" reference to MainWindow class, not informacion class

this is the constructor of MainWindow.cpp

MainWindow::MainWindow(QWidget *parent) :
QMainWindow(parent),
ui(new Ui::MainWindow)
{

ui->setupUi(this);

QFontDatabase::addApplicationFont(":/fonts/imagenes/usuziv2.ttf");

 Aeropuerto *obj = new Aeropuerto();
 Avion *obj2 = new Avion();

 informacion *info = new informacion(this);
 connect(ui->pushButton, SIGNAL (click()) , info , SLOT(hideEditar()));

 obj->crearFlota();
 obj->flotaAviones.sort(obj2->mayorNombre);

 list<Avion>::iterator it;
 int i = 0;
for(it=obj->flotaAviones.begin(); it!=obj->flotaAviones.end();  it++)
{
ui->comboBox->insertItem(i, (*it).getAerolinea());

i++;
}

 obj->xt = obj->flotaAviones.begin();
 obj->yt = obj->xt;

ui->textBrowser->hide();
ui->mainToolBar->hide();
ui->statusBar->hide();
}

//this is informacion.h

#ifndef INFORMACION_H
#define INFORMACION_H

#include <QDialog>
#include <list>

namespace Ui {
class informacion;
}

class informacion : public QDialog
{
Q_OBJECT

public:
explicit informacion(QWidget *parent = 0);

~informacion();

private slots:
void on_pushButton_clicked();

void on_pushButton_2_clicked();

void on_editar_clicked();

void on_ok_clicked();

public slots:
void hideEditar();

private:
Ui::informacion *ui;

};

//and this is definition of hideEditar() on information.cpp

void informacion::hideEditar()
{
ui->editar->hide();
}

mrjj

Hi
Can you show implementation of
informacion(QWidget *parent = 0);
I suspect the UI is not newed and it crashes with
ui->editar->hide(); as ui might not be setup via the normal
setupUI()
So check if you have code that initilize
Ui::informacion *ui;
like
ui(new Ui::informacion)

Note that
informacion *info = new informacion(this);"
"this" is used as parent as param name of the constructor suggests.

Cuban Akira

@mrjj said in how to modify mainform.ui components from other form, and vice versa:

spect

//information.cpp constructor

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

Aeropuerto *obj = new Aeropuerto();
list<Avion>::iterator it;

//visual
ui->aerolineaLE->hide();
ui->aerolineaEditarLabel->hide();
ui->codigoLE->hide();
ui->asientosLE->hide();
ui->equipajeLE->hide();
ui->pilotoLE->hide();
ui->editarHeadLine->hide();

ui->ok->hide();

obj->xt=obj->flotaAviones.begin();

ui->aerolinealabel->setText((*obj->xt).getAerolinea());
ui->asientosRed->setText(QString::number((*obj->xt).getCantidadAsientos()));
ui->asientoslabel->setText(QString::number((*obj->xt).getCantidadAsientos()));
ui->equipajelabel->setText(QString::number((*obj->xt).getCapacidadEquipajeRestante()));
ui->codigolabel->setText((*obj->xt).getCodigo());
ui->pilotolabel->setText((*obj->xt).getNombrePiloto());
ui->equipajeNRed->setText(QString::number((*obj->xt).getCapacidadEquipajeRestante()));
ui->aerolineaRed->setText((*obj->xt).getAerolinea());

//mostrando
ui->aerolinealabel->show();
ui->codigolabel->show();
ui->asientoslabel->show();
ui->equipajelabel->show();
ui->pilotolabel->show();
ui->aerolinealabel->show();
ui->aerolineaRed->show();
ui->equipajeNRed->show();
ui->pushButton->show();
ui->pushButton_2->show();
ui->editar->show();

//numeros rojos
if((*obj->xt).getCantidadAsientos()==0)
{
ui->aerolinealabel->hide();
ui->label_4->hide();
ui->asientoslabel->hide();
}
if((*obj->xt).getCapacidadEquipajeRestante()==0)
{
ui->aerolinealabel->hide();
ui->label_3->hide();
ui->equipajelabel->hide();
}

}

mrjj

@Cuban-Akira
Ok, that looks all right as far as i can see.
You have to find out what line it crash on so its time to use the debugger and
single step through MainWindow and see what makes it crash.
Seems to be fine with the connect . So i assume its something else.

Cuban Akira

@mrjj said in how to modify mainform.ui components from other form, and vice versa:
when i comment
/* informacion info = new informacion(this);
connect(ui->pushButton, SIGNAL (click()) , info , SLOT(hideEditar()));/

debuging i found why crashes, and fix it, i testing right now

Cuban Akira

@mrjj
i test the signal slot system in my app, and i have gaps, thing i dont understand yet, i solved all the remaining problem and task taking other ways,
i have this questions unclear:
1 - if i want to connect a button.clicked() signal to a x slot, i have to declare it(the signal) in the class.h and class.cpp or the moc file create it ???
2 - in the funtion connect, i use 4 arguments, (object, signal, recObject, slot ), if the signal es from a button, the object may be the formclass or the button
3 - i see a lot examples with the word "emit", i have to use always?, all the bodys of slots funtion may have "emit"?
4 - how to create a signal, ?? cause i cannnot implemet a body in the class.cpp, just declare it in the class.h

mrjj

Hi
1:
Always in the .cpp and .h for the slots.
the moc files are generated and will override any changes you make for them.
Notice that a slot always have its header in .h and the body in .cpp
A custom signal on the other hand, only has header in .h as it has no body.
Terms used:
header = the signature of the function/method/slot like
void SomeSlot(int param);
Body = the actual implementation of the slot
void Classsname::SomeSlot(int param) {
---code--
}
on the other hand a signal would just be
void SomeSignal(int param); in .h and nothing in .cpp.

2:
You may send a signal to any other class that inherit QObject and has Q_OBJECT macro and the slot that matches
class Someclass: public QObject {
Q_OBJECT

3:
emit is used to send the signal.
So if you create new signals, its how you "send" them
emit MySignal()

4:
a signal is just a method header/signature and listed under signals:
signals:
void MySignal(); // your custom signal.

Did you read
http://doc.qt.io/qt-5/signalsandslots.html
?