dialog.cpp Example File

loopback/dialog.cpp
/****************************************************************************
**
** Copyright (C) 2013 Digia Plc and/or its subsidiary(-ies).
** Contact: http://www.qt-project.org/legal
**
** This file is part of the examples of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:BSD$
** You may use this file under the terms of the BSD license as follows:
**
** "Redistribution and use in source and binary forms, with or without
** modification, are permitted provided that the following conditions are
** met:
**   * Redistributions of source code must retain the above copyright
**     notice, this list of conditions and the following disclaimer.
**   * Redistributions in binary form must reproduce the above copyright
**     notice, this list of conditions and the following disclaimer in
**     the documentation and/or other materials provided with the
**     distribution.
**   * Neither the name of Digia Plc and its Subsidiary(-ies) nor the names
**     of its contributors may be used to endorse or promote products derived
**     from this software without specific prior written permission.
**
**
** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
** A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
** OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
** SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
** LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
** DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
** THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
** (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
** OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE."
**
** $QT_END_LICENSE$
**
****************************************************************************/

#include <QtWidgets>
#include <QtNetwork>

#include "dialog.h"

static const int TotalBytes = 50 * 1024 * 1024;
static const int PayloadSize = 64 * 1024; // 64 KB

Dialog::Dialog(QWidget *parent)
    : QDialog(parent)
{
    clientProgressBar = new QProgressBar;
    clientStatusLabel = new QLabel(tr("Client ready"));
    serverProgressBar = new QProgressBar;
    serverStatusLabel = new QLabel(tr("Server ready"));

    startButton = new QPushButton(tr("&Start"));
    quitButton = new QPushButton(tr("&Quit"));

    buttonBox = new QDialogButtonBox;
    buttonBox->addButton(startButton, QDialogButtonBox::ActionRole);
    buttonBox->addButton(quitButton, QDialogButtonBox::RejectRole);

    connect(startButton, SIGNAL(clicked()), this, SLOT(start()));
    connect(quitButton, SIGNAL(clicked()), this, SLOT(close()));
    connect(&tcpServer, SIGNAL(newConnection()),
            this, SLOT(acceptConnection()));
    connect(&tcpClient, SIGNAL(connected()), this, SLOT(startTransfer()));
    connect(&tcpClient, SIGNAL(bytesWritten(qint64)),
            this, SLOT(updateClientProgress(qint64)));
    connect(&tcpClient, SIGNAL(error(QAbstractSocket::SocketError)),
            this, SLOT(displayError(QAbstractSocket::SocketError)));

    QVBoxLayout *mainLayout = new QVBoxLayout;
    mainLayout->addWidget(clientProgressBar);
    mainLayout->addWidget(clientStatusLabel);
    mainLayout->addWidget(serverProgressBar);
    mainLayout->addWidget(serverStatusLabel);
    mainLayout->addStretch(1);
    mainLayout->addSpacing(10);
    mainLayout->addWidget(buttonBox);
    setLayout(mainLayout);

    setWindowTitle(tr("Loopback"));
}

void Dialog::start()
{
    startButton->setEnabled(false);

#ifndef QT_NO_CURSOR
    QApplication::setOverrideCursor(Qt::WaitCursor);
#endif

    bytesWritten = 0;
    bytesReceived = 0;

    while (!tcpServer.isListening() && !tcpServer.listen()) {
        QMessageBox::StandardButton ret = QMessageBox::critical(this,
                                        tr("Loopback"),
                                        tr("Unable to start the test: %1.")
                                        .arg(tcpServer.errorString()),
                                        QMessageBox::Retry
                                        | QMessageBox::Cancel);
        if (ret == QMessageBox::Cancel)
            return;
    }

    serverStatusLabel->setText(tr("Listening"));
    clientStatusLabel->setText(tr("Connecting"));
    tcpClient.connectToHost(QHostAddress::LocalHost, tcpServer.serverPort());
}

void Dialog::acceptConnection()
{
    tcpServerConnection = tcpServer.nextPendingConnection();
    connect(tcpServerConnection, SIGNAL(readyRead()),
            this, SLOT(updateServerProgress()));
    connect(tcpServerConnection, SIGNAL(error(QAbstractSocket::SocketError)),
            this, SLOT(displayError(QAbstractSocket::SocketError)));

    serverStatusLabel->setText(tr("Accepted connection"));
    tcpServer.close();
}

void Dialog::startTransfer()
{
    // called when the TCP client connected to the loopback server
    bytesToWrite = TotalBytes - (int)tcpClient.write(QByteArray(PayloadSize, '@'));
    clientStatusLabel->setText(tr("Connected"));
}

void Dialog::updateServerProgress()
{
    bytesReceived += (int)tcpServerConnection->bytesAvailable();
    tcpServerConnection->readAll();

    serverProgressBar->setMaximum(TotalBytes);
    serverProgressBar->setValue(bytesReceived);
    serverStatusLabel->setText(tr("Received %1MB")
                               .arg(bytesReceived / (1024 * 1024)));

    if (bytesReceived == TotalBytes) {
        tcpServerConnection->close();
        startButton->setEnabled(true);
#ifndef QT_NO_CURSOR
        QApplication::restoreOverrideCursor();
#endif
    }
}

void Dialog::updateClientProgress(qint64 numBytes)
{
    // callen when the TCP client has written some bytes
    bytesWritten += (int)numBytes;

    // only write more if not finished and when the Qt write buffer is below a certain size.
    if (bytesToWrite > 0 && tcpClient.bytesToWrite() <= 4*PayloadSize)
        bytesToWrite -= (int)tcpClient.write(QByteArray(qMin(bytesToWrite, PayloadSize), '@'));

    clientProgressBar->setMaximum(TotalBytes);
    clientProgressBar->setValue(bytesWritten);
    clientStatusLabel->setText(tr("Sent %1MB")
                               .arg(bytesWritten / (1024 * 1024)));
}

void Dialog::displayError(QAbstractSocket::SocketError socketError)
{
    if (socketError == QTcpSocket::RemoteHostClosedError)
        return;

    QMessageBox::information(this, tr("Network error"),
                             tr("The following error occurred: %1.")
                             .arg(tcpClient.errorString()));

    tcpClient.close();
    tcpServer.close();
    clientProgressBar->reset();
    serverProgressBar->reset();
    clientStatusLabel->setText(tr("Client ready"));
    serverStatusLabel->setText(tr("Server ready"));
    startButton->setEnabled(true);
#ifndef QT_NO_CURSOR
    QApplication::restoreOverrideCursor();
#endif
}

© 2015 The Qt Company Ltd. Documentation contributions included herein are the copyrights of their respective owners. The documentation provided herein is licensed under the terms of the GNU Free Documentation License version 1.3 as published by the Free Software Foundation. Qt and respective logos are trademarks of The Qt Company Ltd in Finland and/or other countries worldwide. All other trademarks are property of their respective owners.