How to use methods of an object from a different class?

[jsulm]

@bask185 Can you show the whole code where

Keyboard *Kboard = new Keyboard();
   //connect(Kboard, &Keyboard::KeyPressed, this &MainWindow::send);
   connect(Kboard, &Keyboard::KeyPressed, this, &MainWindow::send);

is embedded?

[bask185]

@jsulm said in How to use methods of an object from a different class?:

@bask185 Can you show the whole code where

Keyboard *Kboard = new Keyboard();
   //connect(Kboard, &Keyboard::KeyPressed, this &MainWindow::send);
   connect(Kboard, &Keyboard::KeyPressed, this, &MainWindow::send);

is embedded?
I don't know what you mean??

I moved Keyboard *Kboard; to the global variables of mainwindow but it seems that does not make a difference. Button 'a' of the keyboard still does not trigger the send function in the main window

[jsulm]

@bask185 Can you please post your code? Else I don't know what is wrong.

[J.Hilk]

@bask185

what @jsulm meant, is, can you post the whole content between the brackets {} where

Keyboard *Kboard = new Keyboard();
   //connect(Kboard, &Keyboard::KeyPressed, this &MainWindow::send);
   connect(Kboard, &Keyboard::KeyPressed, this, &MainWindow::send);

is copied out of.

[bask185]

The one with the comma remains ;)

#include "mainwindow.h" // mainwindow.cpp
#include "ui_mainwindow.h"
#include <QPixmap>
#include <QDebug>
#include <QPalette>
#include <QtSerialPort>
#include "keyboard.h"
#include "numpad.h"
QSerialPort *serial;
void readCommand();

char lettres[5][40][16];     // initializes all to be used variables;
int index1 = 0;
int index2 = 0;
int colom[5];
int row[5];
int colorIndex[5];
char c;
Keyboard *Kboard;

MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::MainWindow)
{
    ui->setupUi(this);
    serial = new QSerialPort();
    serial->setPortName("COM4");
    serial->open(QIODevice::ReadWrite);
    serial->setBaudRate(QSerialPort::Baud115200);
    serial->setDataBits(QSerialPort::Data8);
    serial->setParity(QSerialPort::OddParity);
    serial->setStopBits(QSerialPort::OneStop);
    //serial.setFlowControl(QSerialPort::NoFlowControl);
    //serial.open(QIODevice::ReadWrite);

    QPixmap logo(":/resources/img/logo.jpg");
    int w = ui->label->width();
    int h = ui->label->height();
    ui->label->setPixmap(logo.scaled(w,h,Qt::KeepAspectRatio));

    for(int i=0;i<5;i++) {
        for (int j=0;j<40;j++) {
            for (int k=0;k<16;k++){
                lettres[i][j][k] =' ';   // initializes the letters array
            }
        }
    }
   connect(serial, &QSerialPort::readyRead, this, &MainWindow::serialReceived);

   Kboard = new Keyboard();
   connect(Kboard, &Keyboard::KeyPressed, this, &MainWindow::send);
}

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

void MainWindow::serialReceived()
{
    QByteArray b = serial->readAll();
    qDebug() << b;
}

void MainWindow::send(QString c)
{
  serial->write("c");
  qDebug() << "hello world " << c;
}

#include "keyboard.h" //keyboard.cpp
#include "ui_keyboard.h"
#include <QtSerialPort>
#include "mainwindow.h"


bool caps = true, shift = true;

Keyboard::Keyboard(QWidget *parent) :
    QDialog(parent),
    ui(new Ui::Keyboard)

{
    ui->setupUi(this);
}

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

void Keyboard::on_a_clicked()
{
   QString c;
   c = ui->a->text();
   emit KeyPressed(c);
   qDebug() << c;

   if(caps == true && shift == false){ // disables the effect of the shift key when any lettre has been pressed.
       shift = false;
       on_shift1_clicked();
   }
}

#ifndef MAINWINDOW_H //main window.h
#define MAINWINDOW_H

#include <QMainWindow>
#include "keyboard.h"
#include "numpad.h"


namespace Ui {
class MainWindow;
}

class MainWindow : public QMainWindow
{
    Q_OBJECT

public:
    explicit MainWindow(QWidget *parent = 0);
    ~MainWindow();

private slots:
    void send(QString c);

private:
    Ui::MainWindow *ui;
    Keyboard *keyboard;
    Numpad *numpad;
};

#endif // MAINWINDOW_H

#ifndef KEYBOARD_H
#define KEYBOARD_H

#include <QDialog>

namespace Ui {  //keyboard.h
class Keyboard;
}

class Keyboard : public QDialog
{
    Q_OBJECT

public:
    explicit Keyboard(QWidget *parent = 0);
    ~Keyboard();
signals:
    void KeyPressed(QString);

private slots:
    void on_a_clicked();
    

private:
    Ui::Keyboard *ui;
};

#endif // KEYBOARD_H

[jsulm]

@bask185 One note: why do you use global variables? This is bad habit!
For example Kboard should be a member variable of your MainWindow class.

[bask185]

idk to get it to work I suppose, but I should declare it in the constructor above the connect function??

In processing I sometimes use global variables because I can acces and modify them in every class I write. In Qt I know very little of what the firetruck I am doing. I do know that in Qt it is a lot more work to get an exact same application than in processing..

[J.Hilk]

@bask185 said in How to use methods of an object from a different class?:

Keyboard *keyboard;

I think I found the mixup,

You have Keyboard as a priavte member of your mainwindow.h, as it should be, and as a global Variable too.

I think the instance of your keyboard, that you show and have input of, is not the one you connected your Signal from.

Change that.

[jsulm]

@bask185 said in How to use methods of an object from a different class?:

void MainWindow::send(QString c)
{
serial->write("c");
qDebug() << "hello world " << c;
}

Can you try to comment out serial->write("c"); and try again?
Also: I guess you want to send the string/character entered by user over serial bus, right?
In that case you should change

serial->write("c");

to

serial->write(c.toLatin1()); // If you only use ASCII characters

[Eeli K]

@bask185 I didn't know you know so little about C++ and Qt. It's true that C++ is in many ways a low-level language. Qt takes it a bit higher, but certainly it's still means more work for certain things than many other languages. But on the other hand C++ is on the most popular and used general purpose languages in the world, and unlike with processing, you can call yourself a real programmer if you master C++ and Qt. Every language has its place and has pros and cons. If you want to just get one program done in your life C++ isn't the right language for you, otherwise it pays back what you put into learning it.

[bask185]

@J.Hilk said in How to use methods of an object from a different class?:

@bask185 said in How to use methods of an object from a different class?:

Keyboard *keyboard;

I think I found the mixup,

You have Keyboard as a priavte member of your mainwindow.h, as it should be, and as a global Variable too.

I think the instance of your keyboard, that you show and have input of, is not the one you connected your Signal from.

Change that.

Application Output:  hello world   "a"   // we have a winner!
                     hello world  "A" // < caps works too :D

My thank is great Y'all

@jsulm said in How to use methods of an object from a different class?:

I guess you want to send the string/character entered by user over serial bus, right?

was it that obvious :P?

In that case you should change
serial->write("c");

to
serial->write(c.toLatin1()); // If you only use ASCII characters

Application Output:  "\x06\x04\x01""a"  // < proper respons of the arduino for receiving the 'a'. Tnx ;)

sigh though... in processing or arduino or whatever I usually send.. just integers or longs. Vague Qt syntax with & * :: private public and what if I want to send a long variable over serial port would I need to characterize all 10 numbers and send 10 bytes instead of 4????

@Eeli-K said in How to use methods of an object from a different class?:

@bask185 I didn't know you know so little about C++ and Qt. It's true that C++ is in many ways a low-level language. Qt takes it a bit higher, but certainly it's still means more work for certain things than many other languages. But on the other hand C++ is on the most popular and used general purpose languages in the world, and unlike with processing, you can call yourself a real programmer if you master C++ and Qt. Every language has its place and has pros and cons. If you want to just get one program done in your life C++ isn't the right language for you, otherwise it pays back what you put into learning it.

we had a few lessons in C++ in my first year in visual studios but even there we would not use :: privates and publics, (the latter 2 we got with java). And as said before I only learned how to use pointers with arrays and not with functions.

But regardless, I almost have my bachelor degree in electrical engineering and learning a new programming language from scrap is what we do.

[jsulm]

@bask185 said in How to use methods of an object from a different class?:

we had a few lessons in C++ in my first year in visual studios but even there we would not use :: privates and publics

Then those were not really C++ lessons. public/private (data encapsulation) belong to core concepts in C++ (and any other object oriented programming language).

"what if I want to send a long variable over serial port would I need to characterize all 10 numbers and send 10 bytes instead of 4" - no.
From the user you will get a string like "12345".
Then convert it to int:

long int number = c.toLong();

And then send the number to Arduino.

[J.Hilk]

@bask185 said in How to use methods of an object from a different class?:

sigh though... in processing or arduino or whatever I usually send.. just integers or longs. Vague Qt syntax with & * :: private public and what if I want to send a long variable over serial port would I need to characterize all 10 numbers and send 10 bytes instead of 4????

QSerialPort::writeData has a max length of qint64 , long long int and __int64 respectively so you should be fine sending 'long' variables.