QDialogButtonBox的用法

#include "dialog.h"

#include <QtNetwork>
#include <QtWidgets>

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, &QAbstractButton::clicked, this, &Dialog::start);
connect(quitButton, &QAbstractButton::clicked, this, &QWidget::close);
connect(&tcpServer, &QTcpServer::newConnection,
this, &Dialog::acceptConnection);
connect(&tcpClient, &QAbstractSocket::connected, this, &Dialog::startTransfer);
connect(&tcpClient, &QIODevice::bytesWritten,
this, &Dialog::updateClientProgress);
connect(&tcpClient, QOverload<QAbstractSocket::SocketError>::of(&QAbstractSocket::error),
this, &Dialog::displayError);

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();
if (!tcpServerConnection) {
serverStatusLabel->setText(tr("Error: got invalid pending connection!"));
return;
    }

connect(tcpServerConnection, &QIODevice::readyRead,
this, &Dialog::updateServerProgress);
connect(tcpServerConnection,
QOverload<QAbstractSocket::SocketError>::of(&QAbstractSocket::error),
this, &Dialog::displayError);
connect(tcpServerConnection, &QTcpSocket::disconnected,
tcpServerConnection, &QTcpSocket::deleteLater);

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)
{
// called 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 -= 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
}