Signals and slots in Mainwindow

[Bharth]

Hi,
how to pass signal to Mainwindow from other class

MainWindow *mn=new MainWindow();
connect(ui->pushButtonclick,SIGNAL(clicked()),mn,SLOT(slotButton3()));
emit clicked();
delete mn;
its not going to slotButton3() method

[aha_1980]

Hi @Bharth,

MainWindow *mn=new MainWindow();
connect(ui->pushButtonclick,SIGNAL(clicked()),mn,SLOT(slotButton3()));
emit clicked();

Shouldn't that be a signal from the button?

delete mn;

You are deleting the window here, therefore the slot is not called.

You should try the connect code in a Qt Widgets Application (File > New File or Project > Applications > Qt Widgets Application) created by Qt Creator.

Regards

[Larvae]

Is this somewhere in MainWindow? To me this looks like it's from main.cpp

connect can't know ui, so you need to do something like

connect(mn->ui->pushButtonclick,SIGNAL(clicked()),mn,SLOT(slotButton3()));

also, which clicked do you emit? I think it sould be

emit mn->ui->pushbupushButtonclick->clicked();

It's either that or you need to post some more code i think

[TobbY]

@Bharth said in Signals and slots in Mainwindow:

MainWindow *mn=new MainWindow();
connect(ui->pushButtonclick,SIGNAL(clicked()),mn,SLOT(slotButton3()))

simply replace emit clicked(); with ui->pushButtonclick->clicked();
will make your example work // if you want to emit click signal from code only

[Bharth]

form.h
///////////////////////////////////////////////
#include <QWidget>

namespace Ui {
class Form;
}

class Form : public QWidget
{
    Q_OBJECT

public:
    explicit Form(QWidget *parent = nullptr);
    ~Form();
     static void doSomething();
public slots:
     void slotButton1();
     void slotButton2();
signals:
      void clicked();

private:
    Ui::Form *ui;
};
form.cpp
/////////////////////////////////////////////////////
#include "form.h"
#include "ui_form.h"
#include "form2.h"
#include "mainwindow.h"
#include "ui_mainwindow.h"

Form::Form(QWidget *parent) :
    QWidget(parent),
    ui(new Ui::Form)
{
    ui->setupUi(this);
    connect(ui->pushButtonclick, SIGNAL(clicked()), this, SLOT(slotButton1()));
}

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



void Form::slotButton1()
{

MainWindow *mn=new MainWindow();

    connect(ui->pushButtonclick,SIGNAL(clicked()),mn,SLOT(slotButton3()));
    emit ui->pushButtonclick->clicked();
    //delete mn;
}
form2.h
////////////////////////////////////////////////////
#ifndef FORM2_H
#define FORM2_H

#include <QWidget>

namespace Ui {
class Form2;
}

class Form2 : public QWidget
{
    Q_OBJECT

public:
    explicit Form2(QWidget *parent = nullptr);
    ~Form2();

private:
    Ui::Form2 *ui;
};


form2.cpp
/////////////////////////////////////////////
#include "form2.h"
#include "ui_form2.h"

Form2::Form2(QWidget *parent) :
    QWidget(parent),
    ui(new Ui::Form2)
{
    ui->setupUi(this);
}

Form2::~Form2()
{
    delete ui;
}
mainwindow.h
//////////////////////////////////
#ifndef MAINWINDOW_H
#define MAINWINDOW_H

#include <QMainWindow>

namespace Ui {
class MainWindow;
}

class MainWindow : public QMainWindow
{
    Q_OBJECT

public:
    explicit MainWindow(QWidget *parent = nullptr);
    ~MainWindow();
public slots:
    void slotButton();
    void slotButton3();
public:
    Ui::MainWindow *ui;
};

#endif // MAINWINDOW_H
mainwindow.cpp
//////////////////////////////////
#include "mainwindow.h"
#include "ui_mainwindow.h"
#include "form.h"
#include "form2.h"


MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::MainWindow)
{
    ui->setupUi(this);
connect(ui->pushButton, SIGNAL(clicked()), this, SLOT(slotButton()));

}

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

void MainWindow::slotButton()
{
    Form *f1=new Form();

    ui->scrollArea->setWidget(f1);


}

void MainWindow::slotButton3()
{

     Form2 *f=new Form2();
     ui->scrollArea_2->setStyleSheet("background-color:red;");

}

[TobbY]

Hi,
Can you provide code tag from editor (Last in row). it's hard to read like that.

[mrjj]

@TobbY
added code tags.

[TobbY]

@Bharth

It won't go to slotButton3();

in your MainWindow make Form1 and Form2 class variable. instead of creating in function.

Class Form
declare signal clicked();
use:
connect(ui->pushButtonclick, SIGNAL(clicked()), this, SIGNAL(clicked()));
instead
connect(ui->pushButtonclick, SIGNAL(clicked()), this, SLOT(slotButton1()));

Class MainWindow:
MainWindow .h
Form *_form1;
Form2 *_form2;

MainWindow constructor
_form1 = new Form();
connect(form, SIGNAL(clicked()), this, SLOT(slotButton3()));

[Bharth]

it is going to slotButton3 in mainwindow i given qDebug<<" " its showing but their its not adding another widget class to mainwindow

[jsulm]

@Bharth

void MainWindow::slotButton3()
{

     Form2 *f=new Form2();
     ui->scrollArea_2->setStyleSheet("background-color:red;");

}

You do not add the widget to any parent widget or layout and you do not call show() on it...