如何在客户端连接时在QT中更新QGraphicsView

How to update QGraphicsView in QT when client is connected?

本文关键字：更新 QT QGraphicsView 连接 客户端      更新时间：2023-10-16

我在更新QGraphicsView时遇到问题。当我在类 myServer 中调用我的函数 void drawConnection(( 时，我必须更新我的 QGraphicsView 它不起作用，但在函数中我有 qDeubg(( 并且正在调用。据我了解，问题不在于函数调用。

主窗口.h

#ifndef MAINWINDOW_H
#define MAINWINDOW_H
#include <QMainWindow>
#include <QtGui>
#include <QtCore>
#include <QGraphicsScene>
#include <QMouseEvent>
#include <QEvent>
namespace Ui {
class MainWindow;
}
class MainWindow : public QMainWindow
{
Q_OBJECT
public:
explicit MainWindow(QWidget *parent = 0);
~MainWindow();
static MainWindow* GetInstance(QWidget* parent = 0);
int matrix_[10][10];
int fire_[10][10];
int mylife = 10;
public:
Ui::MainWindow *ui;
static MainWindow* mainInstance;
QGraphicsScene *scene;
QGraphicsEllipseItem *ellipse;
QGraphicsRectItem *rectangle;
QGraphicsTextItem *text_;
QGraphicsTextItem *connection;
void mousePressEvent(QMouseEvent *ev);
public:
    //matrix
    void drawing();
    void createMatrix();
    void creatShip();
    //fire
    void createFireMatrix();
    void drawingFire();
    //life
    void drawingYourLife();
public:
    //conection
    void drawConnection();
    void drawDisConnection();
};
#endif // MAINWINDOW_H

主窗口.cpp

MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::MainWindow)
{
    ui->setupUi(this);
}
MainWindow* MainWindow::mainInstance = 0;
MainWindow* MainWindow::GetInstance(QWidget *parent)
{
    if(mainInstance == NULL)
    {
        mainInstance = new MainWindow(parent);
    }
    return mainInstance;
}
void MainWindow::drawConnection()
{
    qDebug()<<"LOL";
    scene = new QGraphicsScene(this);
    ui->graphicsView_5->setScene(scene);
    QFont seriFont("Times",30,QFont::Bold);
    connection = scene->addText("Client is connecting",seriFont);
}

我的服务器.h

#ifndef MYSERVER_H
#define MYSERVER_H
#include <QMainWindow>
#include <QTcpServer>
#include <QTcpSocket>
#include <QDebug>
#include "mainwindow.h"
#include "ui_mainwindow.h"
#include <QMainWindow>
namespace Ui { class MainWindow; }
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

我的服务器.cpp

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

不要表明你的意思qDebug()，在我的情况下，在我的情况下没有调用连接。另外，我看到您正在实现不必要的方法，您可以查看以下示例：财富服务器示例。

我没有实现incomingConnection()方法，但我只使用了信号newConnection和方法nextPendingConnection()。

我的服务器.h 

#ifndef MYSERVER_H
#define MYSERVER_H
#include "mainwindow.h"
#include <QTcpServer>
class MyServer : public QTcpServer
{
public:
    using QTcpServer::QTcpServer;
    void startServer();
private:
    MainWindow* instance = MainWindow::instance();
    void sockReady();
    void sockDisc();
};
#endif // MYSERVER_H

我的服务器.cpp

#include "myserver.h"
#include <QDebug>
#include <QTcpSocket>
void MyServer::startServer()
{
    if(listen(QHostAddress::Any,5555))
        qDebug()<<"LISTEN";
    else
        qDebug()<<"NOT LISTEN";
    connect(this,&QTcpServer::newConnection,this,&MyServer::sockReady);
}
void MyServer::sockReady()
{
    QTcpSocket *socket = nextPendingConnection();
    qDebug()<<"CONNECTED";
    instance->drawConnection();
    connect(socket, &QTcpSocket::disconnected, this, &MyServer::sockDisc);
}
void MyServer::sockDisc()
{
    QTcpSocket *socket = qobject_cast< QTcpSocket *>(sender());
    qDebug()<<"DISCONECT";
    if(socket)
        socket->deleteLater();
}

我已经重新排序了主窗口代码。

主窗口.h

#ifndef MAINWINDOW_H
#define MAINWINDOW_H
#include <QMainWindow>
class QGraphicsTextItem;
class QGraphicsScene;
namespace Ui {
class MainWindow;
}
class MainWindow : public QMainWindow
{
    Q_OBJECT
public:
    static MainWindow *instance(QWidget* parent = 0);
    ~MainWindow();
    void drawConnection();
private:
    MainWindow(QWidget *parent = 0);
    Ui::MainWindow *ui;
    static MainWindow* mInstance;
    QGraphicsScene *scene;
    QGraphicsTextItem *connection;
};
#endif // MAINWINDOW_H

主窗口.cpp

#include "mainwindow.h"
#include "ui_mainwindow.h"
#include <QGraphicsScene>
#include <QGraphicsView>
MainWindow* MainWindow::mInstance = 0;
MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::MainWindow)
{
    ui->setupUi(this);
    scene = new QGraphicsScene(this);
    ui->graphicsView->setScene(scene);
}
MainWindow *MainWindow::instance(QWidget *parent)
{
    if(mInstance == NULL)
        mInstance = new MainWindow(parent);
    return mInstance;
}
MainWindow::~MainWindow()
{
    delete ui;
}
void MainWindow::drawConnection()
{
    QFont seriFont("Times", 30, QFont::Bold);
    connection = scene->addText("Client is connecting",seriFont);
}

完整的示例可以在以下链接中找到。

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