mainwindow.cpp Example File

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 #include "mainwindow.h"
 #include "nicselector.h"
 #include "ui_mainwindow.h"

 MainWindow::MainWindow()
     : ui(new Ui::MainWindow)
 {
     ui->setupUi(this);

     connect(&server, &DtlsServer::errorMessage, this, &MainWindow::addErrorMessage);
     connect(&server, &DtlsServer::warningMessage, this, &MainWindow::addWarningMessage);
     connect(&server, &DtlsServer::infoMessage, this, &MainWindow::addInfoMessage);
     connect(&server, &DtlsServer::datagramReceived, this, &MainWindow::addClientMessage);

     updateUi();
 }

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

 void MainWindow::on_startButton_clicked()
 {
     if (!server.isListening()) {
         NicSelector ipDialog;
         if (ipDialog.exec() == QDialog::Accepted) {
             const QHostAddress address = ipDialog.selectedIp();
             const quint16 port = ipDialog.selectedPort();
             if (address.isNull()) {
                 addErrorMessage(tr("Failed to start listening, no valid address/port"));
             } else if (server.listen(address, port)) {
                 addInfoMessage(tr("Server is listening on address %1 and port %2")
                                  .arg(address.toString())
                                  .arg(port));
             }
         }
     } else {
         server.close();
         addInfoMessage(tr("Server is not accepting new connections"));
     }

     updateUi();
 }

 void MainWindow::on_quitButton_clicked()
 {
     QCoreApplication::exit(0);
 }

 void MainWindow::updateUi()
 {
     server.isListening() ? ui->startButton->setText(tr("Stop listening"))
                          : ui->startButton->setText(tr("Start listening"));
 }

 const QString colorizer(QStringLiteral("<font color=\"%1\">%2</font><br>"));

 void MainWindow::addErrorMessage(const QString &message)
 {
     ui->serverInfo->insertHtml(colorizer.arg(QStringLiteral("Crimson"), message));
 }

 void MainWindow::addWarningMessage(const QString &message)
 {
     ui->serverInfo->insertHtml(colorizer.arg(QStringLiteral("DarkOrange"), message));
 }

 void MainWindow::addInfoMessage(const QString &message)
 {
     ui->serverInfo->insertHtml(colorizer.arg(QStringLiteral("DarkBlue"), message));
 }

 void MainWindow::addClientMessage(const QString &peerInfo, const QByteArray &datagram,
                                   const QByteArray &plainText)
 {
     static const QString messageColor = QStringLiteral("DarkMagenta");
     static const QString formatter = QStringLiteral("<br>---------------"
                                                     "<br>A message from %1"
                                                     "<br>DTLS datagram:<br> %2"
                                                     "<br>As plain text:<br> %3");

     const QString html = formatter.arg(peerInfo, QString::fromUtf8(datagram.toHex(' ')),
                                        QString::fromUtf8(plainText));
     ui->messages->insertHtml(colorizer.arg(messageColor, html));
 }