Send data on Button click via TCP. How to trigger my send method via button click?

ven1ceBeach

Hello guys,

I am a qt beginner so please don't blame me for my question.

I have a simple UI and a server running in the background (in a thread) which should send some data when a button is clicked. The server code is in another class which also contains the sendData method. Now I am looking for the best practice to trigger the sendData method with a button.

Actually, in the thread.cpp I wanted to do something like:

 connect(ui->button1, SIGNAL(clicked()), this, SLOT(sendData()));

But I can not access the ui from my thread class.

I think this is kinda easy to solve but I really couldn't find any solutions.

Here is the full code:

Thread.h

#ifndef THREAD_H
#define THREAD_H

#include <QThread>
#include <QTcpSocket>
#include <QDebug>

class Thread : public QThread
{
    Q_OBJECT
public:
    explicit Thread(int ID, QObject *parent = 0);
    void run();
    void sendData();

signals:
    void error(QTcpSocket::SocketError socketerror);

public slots:
    void readyRead();
    void disconnected();

private:
    QTcpSocket *socket;
    int socketDescriptor;


};

#endif // THREAD_H

Thread.cpp

#include "thread.h"

Thread::Thread(int ID, QObject *parent) : QThread(parent)
{
    this->socketDescriptor = ID;
}

void Thread::run()
{
    qDebug() << socketDescriptor << " Starting Thread";
    socket = new QTcpSocket();

    if(!socket->setSocketDescriptor(this->socketDescriptor))
    {
        emit error(socket->error());
        return;
    }

    connect(socket, SIGNAL(readyRead()), this, SLOT(readyRead()), Qt::DirectConnection);
    connect(socket, SIGNAL(disconnected()), this, SLOT(disconnected()), Qt::DirectConnection);
    // Here is where i wanted to access the buttons signal and trigger the sendData method.

    qDebug() << socketDescriptor << " Client connected";

    exec();

}

void Thread::sendData()
{
    socket->write("Data test");
}

void Thread::readyRead()
{
    QByteArray data = socket->readAll();
    qDebug() << socketDescriptor << " Data in: " << data;
    socket->write(data);
}

void Thread::disconnected()
{
    qDebug() << socketDescriptor << " Client disconnected";
    socket->deleteLater();
    exit(0);
}

MainWindow.h

#ifndef MAINWINDOW_H
#define MAINWINDOW_H

#include "server.h"

#include <QMainWindow>
#include <QFileDialog>
#include <QMessageBox>

QT_BEGIN_NAMESPACE
namespace Ui { class MainWindow; }
QT_END_NAMESPACE

class MainWindow : public QMainWindow
{
    Q_OBJECT

public:
    MainWindow(QWidget *parent = nullptr);
    ~MainWindow();
private slots:


    void on_btn_lightOff_clicked();

private:
    Ui::MainWindow *ui;

};
#endif // MAINWINDOW_H

MainWindow.cpp

#include "mainwindow.h"
#include "ui_mainwindow.h"
#include "server.h"

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

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




void MainWindow::on_btn_lightOff_clicked()
{

}

main.cpp

#include "tcpsocket.h"
#include "server.h"
#include "mainwindow.h"



#include <QApplication>

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
    MainWindow w;
    Server server;
    server.startServer();
    w.show();
    return a.exec();
}

Server.h

#ifndef SERVER_H
#define SERVER_H

#include <QTcpServer>
#include <QDebug>
#include <thread.h>


class Server : public QTcpServer
{
    Q_OBJECT
public:
    explicit Server(QObject *parent = 0);
    void startServer();

signals:

protected:
    void incomingConnection(qintptr  socketDescriptor);

};

#endif // SERVER_H

Server.cpp

#include "server.h"

Server::Server(QObject *parent) : QTcpServer(parent)
{

}

void Server::startServer()
{
    if(!this->listen(QHostAddress::Any,1337))
    {
       qDebug() << "Error starting Server...";
    }
    else
    {
        qDebug() << "Listening...";
    }
}

void Server::incomingConnection(qintptr  socketDescriptor)
{
    qDebug() << socketDescriptor << " Connecting...";
    Thread *thread = new Thread(socketDescriptor,this);
    connect(thread, SIGNAL(finished()), thread, SLOT(deleteLater()));
    thread->start();
}

Christian Ehrlicher

Then do the connect where you have access to both classes. For instance in main when MainWindow returns a pointer of your widget or better somewhere in MainWindow (then MainWindow needs a pointer to the thread).
Why using threads at all here? It's not needed.