#ifndef MYSERVER_H
#define MYSERVER_H

#include <QMainWindow>
#include <QTcpServer>
#include <QTcpSocket>

class myServer: public QTcpServer
{
    Q_OBJECT

public:
    myServer();
    ~myServer();

public:

    QTcpSocket* socket;
    QByteArray Data;
    MainWindow* instance = MainWindow::GetInstance();

public slots:
    void startServer();
    void incomingConnection(int socketDescriptor);
    void sockReady();
    void sockDisc();
};

#endif // MYSERVER_H

#include "myserver.h"
#include "mainwindow.h"
#include "ui_mainwindow.h"
#include <QWidget>
#include <QGraphicsItem>

myServer::myServer(){}
myServer::~myServer(){}

void myServer::startServer()
{
    if(this->listen(QHostAddress::Any,5555))
    {
        qDebug()<<"LISTEN";
    }
    else{
        qDebug()<<"NOT LISTEN";
    }
}

void myServer::incomingConnection(int socketDescriptor)
{
    socket = new QTcpSocket(this);
    socket->setSocketDescriptor(socketDescriptor);

    connect(socket,SIGNAL(readyRead()),this,SLOT(sockReady()));
    connect(socket,SIGNAL(disconnected()),this,SLOT(sockDisc()));

    qDebug()<<socketDescriptor<< "Client connected";
    socket->write("You are connect");
    qDebug()<<"Send client connect status - YES";
}

void myServer::sockReady()
{
    instance->drawConnection();
    instance->drawingenemyLife();
    instance->show();
}

void myServer::sockDisc()
{
    qDebug()<<"DISCONECT";
    instance->drawDisConnection();
    instance->show();
    socket->deleteLater();
}

void MainWindow::mousePressEvent(QMouseEvent *ev)
{
    //Здесь надо вызвать socket->write("SOME TEXT");
}

class MainWindow : public QMainWindow
{
    Q_OBJECT
    ...
signals:
    void messageCreated(const QString& str);
    ...
};

class myServer : public QObject
{
    Q_OBJECT
    ...
public slots:
    void slotSendMessage(const QString& str)
    {
        socket->write(str.toUtf8())
    }
    ...
};

void MainWindow::mousePressEvent(QMouseEvent* ev)
{
    emit messageCreated("Very important message");
}

MainWindow w;
myServer s;
...
QObject::connect(&m, &MainWindow::messageCreated, &s, &myServer::slotSendMessage);