mainwindow.cpp Example File

 /****************************************************************************
 **
 ** Copyright (C) 2015 The Qt Company Ltd.
 ** Contact: http://www.qt.io/licensing/
 **
 ** 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 The Qt Company Ltd 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 <QtGui>

 #include "addtorrentdialog.h"
 #include "mainwindow.h"
 #include "ratecontroller.h"
 #include "torrentclient.h"

 // TorrentView extends QTreeWidget to allow drag and drop.
 class TorrentView : public QTreeWidget
 {
     Q_OBJECT
 public:
     TorrentView(QWidget *parent = 0);

 signals:
     void fileDropped(const QString &fileName);

 protected:
     void dragMoveEvent(QDragMoveEvent *event);
     void dropEvent(QDropEvent *event);
 };

 // TorrentViewDelegate is used to draw the progress bars.
 class TorrentViewDelegate : public QItemDelegate
 {
     Q_OBJECT
 public:
     inline TorrentViewDelegate(MainWindow *mainWindow) : QItemDelegate(mainWindow) {}

     inline void paint(QPainter *painter, const QStyleOptionViewItem &option,
                       const QModelIndex &index ) const
     {
         if (index.column() != 2) {
             QItemDelegate::paint(painter, option, index);
             return;
         }

         // Set up a QStyleOptionProgressBar to precisely mimic the
         // environment of a progress bar.
         QStyleOptionProgressBar progressBarOption;
         progressBarOption.state = QStyle::State_Enabled;
         progressBarOption.direction = QApplication::layoutDirection();
         progressBarOption.rect = option.rect;
         progressBarOption.fontMetrics = QApplication::fontMetrics();
         progressBarOption.minimum = 0;
         progressBarOption.maximum = 100;
         progressBarOption.textAlignment = Qt::AlignCenter;
         progressBarOption.textVisible = true;

         // Set the progress and text values of the style option.
         int progress = qobject_cast<MainWindow *>(parent())->clientForRow(index.row())->progress();
         progressBarOption.progress = progress < 0 ? 0 : progress;
         progressBarOption.text = QString().sprintf("%d%%", progressBarOption.progress);

         // Draw the progress bar onto the view.
         QApplication::style()->drawControl(QStyle::CE_ProgressBar, &progressBarOption, painter);
     }
 };

 MainWindow::MainWindow(QWidget *parent)
     : QMainWindow(parent), quitDialog(0), saveChanges(false)
 {
     // Initialize some static strings
     QStringList headers;
     headers << tr("Torrent") << tr("Peers/Seeds") << tr("Progress")
             << tr("Down rate") << tr("Up rate") << tr("Status");

     // Main torrent list
     torrentView = new TorrentView(this);
     torrentView->setItemDelegate(new TorrentViewDelegate(this));
     torrentView->setHeaderLabels(headers);
     torrentView->setSelectionBehavior(QAbstractItemView::SelectRows);
     torrentView->setAlternatingRowColors(true);
     torrentView->setRootIsDecorated(false);
     setCentralWidget(torrentView);

     // Set header resize modes and initial section sizes
     QFontMetrics fm = fontMetrics();
     QHeaderView *header = torrentView->header();
     header->resizeSection(0, fm.width("typical-name-for-a-torrent.torrent"));
     header->resizeSection(1, fm.width(headers.at(1) + "  "));
     header->resizeSection(2, fm.width(headers.at(2) + "  "));
     header->resizeSection(3, qMax(fm.width(headers.at(3) + "  "), fm.width(" 1234.0 KB/s ")));
     header->resizeSection(4, qMax(fm.width(headers.at(4) + "  "), fm.width(" 1234.0 KB/s ")));
     header->resizeSection(5, qMax(fm.width(headers.at(5) + "  "), fm.width(tr("Downloading") + "  ")));

     // Create common actions
     QAction *newTorrentAction = new QAction(QIcon(":/icons/bottom.png"), tr("Add &new torrent"), this);
     pauseTorrentAction = new QAction(QIcon(":/icons/player_pause.png"), tr("&Pause torrent"), this);
     removeTorrentAction = new QAction(QIcon(":/icons/player_stop.png"), tr("&Remove torrent"), this);

     // File menu
     QMenu *fileMenu = menuBar()->addMenu(tr("&File"));
     fileMenu->addAction(newTorrentAction);
     fileMenu->addAction(pauseTorrentAction);
     fileMenu->addAction(removeTorrentAction);
     fileMenu->addSeparator();
     fileMenu->addAction(QIcon(":/icons/exit.png"), tr("E&xit"), this, SLOT(close()));

     // Help menu
     QMenu *helpMenu = menuBar()->addMenu(tr("&Help"));
     helpMenu->addAction(tr("&About"), this, SLOT(about()));
     helpMenu->addAction(tr("About &Qt"), qApp, SLOT(aboutQt()));

     // Top toolbar
     QToolBar *topBar = new QToolBar(tr("Tools"));
     addToolBar(Qt::TopToolBarArea, topBar);
     topBar->setMovable(false);
     topBar->addAction(newTorrentAction);
     topBar->addAction(removeTorrentAction);
     topBar->addAction(pauseTorrentAction);
     topBar->addSeparator();
     downActionTool = topBar->addAction(QIcon(tr(":/icons/1downarrow.png")), tr("Move down"));
     upActionTool = topBar->addAction(QIcon(tr(":/icons/1uparrow.png")), tr("Move up"));

     // Bottom toolbar
     QToolBar *bottomBar = new QToolBar(tr("Rate control"));
     addToolBar(Qt::BottomToolBarArea, bottomBar);
     bottomBar->setMovable(false);
     downloadLimitSlider = new QSlider(Qt::Horizontal);
     downloadLimitSlider->setRange(0, 1000);
     bottomBar->addWidget(new QLabel(tr("Max download:")));
     bottomBar->addWidget(downloadLimitSlider);
     bottomBar->addWidget((downloadLimitLabel = new QLabel(tr("0 KB/s"))));
     downloadLimitLabel->setFixedSize(QSize(fm.width(tr("99999 KB/s")), fm.lineSpacing()));
     bottomBar->addSeparator();
     uploadLimitSlider = new QSlider(Qt::Horizontal);
     uploadLimitSlider->setRange(0, 1000);
     bottomBar->addWidget(new QLabel(tr("Max upload:")));
     bottomBar->addWidget(uploadLimitSlider);
     bottomBar->addWidget((uploadLimitLabel = new QLabel(tr("0 KB/s"))));
     uploadLimitLabel->setFixedSize(QSize(fm.width(tr("99999 KB/s")), fm.lineSpacing()));

     // Set up connections
     connect(torrentView, SIGNAL(itemSelectionChanged()),
             this, SLOT(setActionsEnabled()));
     connect(torrentView, SIGNAL(fileDropped(QString)),
             this, SLOT(acceptFileDrop(QString)));
     connect(uploadLimitSlider, SIGNAL(valueChanged(int)),
             this, SLOT(setUploadLimit(int)));
     connect(downloadLimitSlider, SIGNAL(valueChanged(int)),
             this, SLOT(setDownloadLimit(int)));
     connect(newTorrentAction, SIGNAL(triggered()),
             this, SLOT(addTorrent()));
     connect(pauseTorrentAction, SIGNAL(triggered()),
             this, SLOT(pauseTorrent()));
     connect(removeTorrentAction, SIGNAL(triggered()),
             this, SLOT(removeTorrent()));
     connect(upActionTool, SIGNAL(triggered(bool)),
             this, SLOT(moveTorrentUp()));
     connect(downActionTool, SIGNAL(triggered(bool)),
             this, SLOT(moveTorrentDown()));

     // Load settings and start
     setWindowTitle(tr("Torrent Client"));
     setActionsEnabled();
     QMetaObject::invokeMethod(this, "loadSettings", Qt::QueuedConnection);
 }

 QSize MainWindow::sizeHint() const
 {
     const QHeaderView *header = torrentView->header();

     // Add up the sizes of all header sections. The last section is
     // stretched, so its size is relative to the size of the width;
     // instead of counting it, we count the size of its largest value.
     int width = fontMetrics().width(tr("Downloading") + "  ");
     for (int i = 0; i < header->count() - 1; ++i)
         width += header->sectionSize(i);

     return QSize(width, QMainWindow::sizeHint().height())
         .expandedTo(QApplication::globalStrut());
 }

 const TorrentClient *MainWindow::clientForRow(int row) const
 {
     // Return the client at the given row.
     return jobs.at(row).client;
 }

 int MainWindow::rowOfClient(TorrentClient *client) const
 {
     // Return the row that displays this client's status, or -1 if the
     // client is not known.
     int row = 0;
     foreach (Job job, jobs) {
         if (job.client == client)
             return row;
         ++row;
     }
     return -1;
 }

 void MainWindow::loadSettings()
 {
     // Load base settings (last working directory, upload/download limits).
     QSettings settings("Trolltech", "Torrent");
     lastDirectory = settings.value("LastDirectory").toString();
     if (lastDirectory.isEmpty())
         lastDirectory = QDir::currentPath();
     int up = settings.value("UploadLimit").toInt();
     int down = settings.value("DownloadLimit").toInt();
     uploadLimitSlider->setValue(up ? up : 170);
     downloadLimitSlider->setValue(down ? down : 550);

     // Resume all previous downloads.
     int size = settings.beginReadArray("Torrents");
     for (int i = 0; i < size; ++i) {
         settings.setArrayIndex(i);
         QByteArray resumeState = settings.value("resumeState").toByteArray();
         QString fileName = settings.value("sourceFileName").toString();
         QString dest = settings.value("destinationFolder").toString();

         if (addTorrent(fileName, dest, resumeState)) {
             TorrentClient *client = jobs.last().client;
             client->setDownloadedBytes(settings.value("downloadedBytes").toLongLong());
             client->setUploadedBytes(settings.value("uploadedBytes").toLongLong());
         }
     }
 }

 bool MainWindow::addTorrent()
 {
     // Show the file dialog, let the user select what torrent to start downloading.
     QString fileName = QFileDialog::getOpenFileName(this, tr("Choose a torrent file"),
                                                     lastDirectory,
                                                     tr("Torrents (*.torrent);;"
                                                        " All files (*.*)"));
     if (fileName.isEmpty())
         return false;
     lastDirectory = QFileInfo(fileName).absolutePath();

     // Show the "Add Torrent" dialog.
     AddTorrentDialog *addTorrentDialog = new AddTorrentDialog(this);
     addTorrentDialog->setTorrent(fileName);
     addTorrentDialog->deleteLater();
     if (!addTorrentDialog->exec())
         return false;

     // Add the torrent to our list of downloads
     addTorrent(fileName, addTorrentDialog->destinationFolder());
     if (!saveChanges) {
         saveChanges = true;
         QTimer::singleShot(1000, this, SLOT(saveSettings()));
     }
     return true;
 }

 void MainWindow::removeTorrent()
 {
     // Find the row of the current item, and find the torrent client
     // for that row.
     int row = torrentView->indexOfTopLevelItem(torrentView->currentItem());
     TorrentClient *client = jobs.at(row).client;

     // Stop the client.
     client->disconnect();
     connect(client, SIGNAL(stopped()), this, SLOT(torrentStopped()));
     client->stop();

     // Remove the row from the view.
     delete torrentView->takeTopLevelItem(row);
     jobs.removeAt(row);
     setActionsEnabled();

     saveChanges = true;
     saveSettings();
 }

 void MainWindow::torrentStopped()
 {
     // Schedule the client for deletion.
     TorrentClient *client = qobject_cast<TorrentClient *>(sender());
     client->deleteLater();

     // If the quit dialog is shown, update its progress.
     if (quitDialog) {
         if (++jobsStopped == jobsToStop)
             quitDialog->close();
     }
 }

 void MainWindow::torrentError(TorrentClient::Error)
 {
     // Delete the client.
     TorrentClient *client = qobject_cast<TorrentClient *>(sender());
     int row = rowOfClient(client);
     QString fileName = jobs.at(row).torrentFileName;
     jobs.removeAt(row);

     // Display the warning.
     QMessageBox::warning(this, tr("Error"),
                          tr("An error occurred while downloading %0: %1")
                          .arg(fileName)
                          .arg(client->errorString()));

     delete torrentView->takeTopLevelItem(row);
     client->deleteLater();
 }

 bool MainWindow::addTorrent(const QString &fileName, const QString &destinationFolder,
                             const QByteArray &resumeState)
 {
     // Check if the torrent is already being downloaded.
     foreach (Job job, jobs) {
         if (job.torrentFileName == fileName && job.destinationDirectory == destinationFolder) {
             QMessageBox::warning(this, tr("Already downloading"),
                                  tr("The torrent file %1 is "
                                     "already being downloaded.").arg(fileName));
             return false;
         }
     }

     // Create a new torrent client and attempt to parse the torrent data.
     TorrentClient *client = new TorrentClient(this);
     if (!client->setTorrent(fileName)) {
         QMessageBox::warning(this, tr("Error"),
                              tr("The torrent file %1 cannot not be opened/resumed.").arg(fileName));
         delete client;
         return false;
     }
     client->setDestinationFolder(destinationFolder);
     client->setDumpedState(resumeState);

     // Setup the client connections.
     connect(client, SIGNAL(stateChanged(TorrentClient::State)), this, SLOT(updateState(TorrentClient::State)));
     connect(client, SIGNAL(peerInfoUpdated()), this, SLOT(updatePeerInfo()));
     connect(client, SIGNAL(progressUpdated(int)), this, SLOT(updateProgress(int)));
     connect(client, SIGNAL(downloadRateUpdated(int)), this, SLOT(updateDownloadRate(int)));
     connect(client, SIGNAL(uploadRateUpdated(int)), this, SLOT(updateUploadRate(int)));
     connect(client, SIGNAL(stopped()), this, SLOT(torrentStopped()));
     connect(client, SIGNAL(error(TorrentClient::Error)), this, SLOT(torrentError(TorrentClient::Error)));

     // Add the client to the list of downloading jobs.
     Job job;
     job.client = client;
     job.torrentFileName = fileName;
     job.destinationDirectory = destinationFolder;
     jobs << job;

     // Create and add a row in the torrent view for this download.
     QTreeWidgetItem *item = new QTreeWidgetItem(torrentView);

     QString baseFileName = QFileInfo(fileName).fileName();
     if (baseFileName.toLower().endsWith(".torrent"))
         baseFileName.remove(baseFileName.size() - 8);

     item->setText(0, baseFileName);
     item->setToolTip(0, tr("Torrent: %1<br>Destination: %2")
                      .arg(baseFileName).arg(destinationFolder));
     item->setText(1, tr("0/0"));
     item->setText(2, "0");
     item->setText(3, "0.0 KB/s");
     item->setText(4, "0.0 KB/s");
     item->setText(5, tr("Idle"));
     item->setFlags(item->flags() & ~Qt::ItemIsEditable);
     item->setTextAlignment(1, Qt::AlignHCenter);

     if (!saveChanges) {
         saveChanges = true;
         QTimer::singleShot(5000, this, SLOT(saveSettings()));
     }
     client->start();
     return true;
 }

 void MainWindow::saveSettings()
 {
     if (!saveChanges)
       return;
     saveChanges = false;

     // Prepare and reset the settings
     QSettings settings("Trolltech", "Torrent");
     settings.clear();

     settings.setValue("LastDirectory", lastDirectory);
     settings.setValue("UploadLimit", uploadLimitSlider->value());
     settings.setValue("DownloadLimit", downloadLimitSlider->value());

     // Store data on all known torrents
     settings.beginWriteArray("Torrents");
     for (int i = 0; i < jobs.size(); ++i) {
         settings.setArrayIndex(i);
         settings.setValue("sourceFileName", jobs.at(i).torrentFileName);
         settings.setValue("destinationFolder", jobs.at(i).destinationDirectory);
         settings.setValue("uploadedBytes", jobs.at(i).client->uploadedBytes());
         settings.setValue("downloadedBytes", jobs.at(i).client->downloadedBytes());
         settings.setValue("resumeState", jobs.at(i).client->dumpedState());
     }
     settings.endArray();
     settings.sync();
 }

 void MainWindow::updateState(TorrentClient::State)
 {
     // Update the state string whenever the client's state changes.
     TorrentClient *client = qobject_cast<TorrentClient *>(sender());
     int row = rowOfClient(client);
     QTreeWidgetItem *item = torrentView->topLevelItem(row);
     if (item) {
         item->setToolTip(0, tr("Torrent: %1<br>Destination: %2<br>State: %3")
                          .arg(jobs.at(row).torrentFileName)
                          .arg(jobs.at(row).destinationDirectory)
                          .arg(client->stateString()));

         item->setText(5, client->stateString());
     }
     setActionsEnabled();
 }

 void MainWindow::updatePeerInfo()
 {
     // Update the number of connected, visited, seed and leecher peers.
     TorrentClient *client = qobject_cast<TorrentClient *>(sender());
     int row = rowOfClient(client);

     QTreeWidgetItem *item = torrentView->topLevelItem(row);
     item->setText(1, tr("%1/%2").arg(client->connectedPeerCount())
                   .arg(client->seedCount()));
 }

 void MainWindow::updateProgress(int percent)
 {
     TorrentClient *client = qobject_cast<TorrentClient *>(sender());
     int row = rowOfClient(client);

     // Update the progressbar.
     QTreeWidgetItem *item = torrentView->topLevelItem(row);
     if (item)
         item->setText(2, QString::number(percent));
 }

 void MainWindow::setActionsEnabled()
 {
     // Find the view item and client for the current row, and update
     // the states of the actions.
     QTreeWidgetItem *item = 0;
     if (!torrentView->selectedItems().isEmpty())
         item = torrentView->selectedItems().first();
     TorrentClient *client = item ? jobs.at(torrentView->indexOfTopLevelItem(item)).client : 0;
     bool pauseEnabled = client && ((client->state() == TorrentClient::Paused)
                                        ||  (client->state() > TorrentClient::Preparing));

     removeTorrentAction->setEnabled(item != 0);
     pauseTorrentAction->setEnabled(item != 0 && pauseEnabled);

     if (client && client->state() == TorrentClient::Paused) {
         pauseTorrentAction->setIcon(QIcon(":/icons/player_play.png"));
         pauseTorrentAction->setText(tr("Resume torrent"));
     } else {
         pauseTorrentAction->setIcon(QIcon(":/icons/player_pause.png"));
         pauseTorrentAction->setText(tr("Pause torrent"));
     }

     int row = torrentView->indexOfTopLevelItem(item);
     upActionTool->setEnabled(item && row != 0);
     downActionTool->setEnabled(item && row != jobs.size() - 1);
 }

 void MainWindow::updateDownloadRate(int bytesPerSecond)
 {
     // Update the download rate.
     TorrentClient *client = qobject_cast<TorrentClient *>(sender());
     int row = rowOfClient(client);
     QString num;
     num.sprintf("%.1f KB/s", bytesPerSecond / 1024.0);
     torrentView->topLevelItem(row)->setText(3, num);

     if (!saveChanges) {
         saveChanges = true;
         QTimer::singleShot(5000, this, SLOT(saveSettings()));
     }
 }

 void MainWindow::updateUploadRate(int bytesPerSecond)
 {
     // Update the upload rate.
     TorrentClient *client = qobject_cast<TorrentClient *>(sender());
     int row = rowOfClient(client);
     QString num;
     num.sprintf("%.1f KB/s", bytesPerSecond / 1024.0);
     torrentView->topLevelItem(row)->setText(4, num);

     if (!saveChanges) {
         saveChanges = true;
         QTimer::singleShot(5000, this, SLOT(saveSettings()));
     }
 }

 void MainWindow::pauseTorrent()
 {
     // Pause or unpause the current torrent.
     int row = torrentView->indexOfTopLevelItem(torrentView->currentItem());
     TorrentClient *client = jobs.at(row).client;
     client->setPaused(client->state() != TorrentClient::Paused);
     setActionsEnabled();
 }

 void MainWindow::moveTorrentUp()
 {
     QTreeWidgetItem *item = torrentView->currentItem();
     int row = torrentView->indexOfTopLevelItem(item);
     if (row == 0)
         return;

     Job tmp = jobs.at(row - 1);
     jobs[row - 1] = jobs[row];
     jobs[row] = tmp;

     QTreeWidgetItem *itemAbove = torrentView->takeTopLevelItem(row - 1);
     torrentView->insertTopLevelItem(row, itemAbove);
     setActionsEnabled();
 }

 void MainWindow::moveTorrentDown()
 {
     QTreeWidgetItem *item = torrentView->currentItem();
     int row = torrentView->indexOfTopLevelItem(item);
     if (row == jobs.size() - 1)
         return;

     Job tmp = jobs.at(row + 1);
     jobs[row + 1] = jobs[row];
     jobs[row] = tmp;

     QTreeWidgetItem *itemAbove = torrentView->takeTopLevelItem(row + 1);
     torrentView->insertTopLevelItem(row, itemAbove);
     setActionsEnabled();
 }

 static int rateFromValue(int value)
 {
     int rate = 0;
     if (value >= 0 && value < 250) {
         rate = 1 + int(value * 0.124);
     } else if (value < 500) {
         rate = 32 + int((value - 250) * 0.384);
     } else if (value < 750) {
         rate = 128 + int((value - 500) * 1.536);
     } else {
         rate = 512 + int((value - 750) * 6.1445);
     }
     return rate;
 }

 void MainWindow::setUploadLimit(int value)
 {
     int rate = rateFromValue(value);
     uploadLimitLabel->setText(tr("%1 KB/s").arg(QString().sprintf("%4d", rate)));
     RateController::instance()->setUploadLimit(rate * 1024);
 }

 void MainWindow::setDownloadLimit(int value)
 {
     int rate = rateFromValue(value);
     downloadLimitLabel->setText(tr("%1 KB/s").arg(QString().sprintf("%4d", rate)));
     RateController::instance()->setDownloadLimit(rate * 1024);
 }

 void MainWindow::about()
 {
     QLabel *icon = new QLabel;
     icon->setPixmap(QPixmap(":/icons/peertopeer.png"));

     QLabel *text = new QLabel;
     text->setWordWrap(true);
     text->setText("<p>The <b>Torrent Client</b> example demonstrates how to"
                   " write a complete peer-to-peer file sharing"
                   " application using Qt's network and thread classes.</p>"
                   "<p>This feature complete client implementation of"
                   " the BitTorrent protocol can efficiently"
                   " maintain several hundred network connections"
                   " simultaneously.</p>");

     QPushButton *quitButton = new QPushButton("OK");

     QHBoxLayout *topLayout = new QHBoxLayout;
     topLayout->setMargin(10);
     topLayout->setSpacing(10);
     topLayout->addWidget(icon);
     topLayout->addWidget(text);

     QHBoxLayout *bottomLayout = new QHBoxLayout;
     bottomLayout->addStretch();
     bottomLayout->addWidget(quitButton);
     bottomLayout->addStretch();

     QVBoxLayout *mainLayout = new QVBoxLayout;
     mainLayout->addLayout(topLayout);
     mainLayout->addLayout(bottomLayout);

     QDialog about(this);
     about.setModal(true);
     about.setWindowTitle(tr("About Torrent Client"));
     about.setLayout(mainLayout);

     connect(quitButton, SIGNAL(clicked()), &about, SLOT(close()));

     about.exec();
 }

 void MainWindow::acceptFileDrop(const QString &fileName)
 {
     // Create and show the "Add Torrent" dialog.
     AddTorrentDialog *addTorrentDialog = new AddTorrentDialog;
     lastDirectory = QFileInfo(fileName).absolutePath();
     addTorrentDialog->setTorrent(fileName);
     addTorrentDialog->deleteLater();
     if (!addTorrentDialog->exec())
         return;

     // Add the torrent to our list of downloads.
     addTorrent(fileName, addTorrentDialog->destinationFolder());
     saveSettings();
 }

 void MainWindow::closeEvent(QCloseEvent *)
 {
     if (jobs.isEmpty())
         return;

     // Save upload / download numbers.
     saveSettings();
     saveChanges = false;

     quitDialog = new QProgressDialog(tr("Disconnecting from trackers"), tr("Abort"), 0, jobsToStop, this);

     // Stop all clients, remove the rows from the view and wait for
     // them to signal that they have stopped.
     jobsToStop = 0;
     jobsStopped = 0;
     foreach (Job job, jobs) {
         ++jobsToStop;
         TorrentClient *client = job.client;
         client->disconnect();
         connect(client, SIGNAL(stopped()), this, SLOT(torrentStopped()));
         client->stop();
         delete torrentView->takeTopLevelItem(0);
     }

     if (jobsToStop > jobsStopped)
         quitDialog->exec();
     quitDialog->deleteLater();
     quitDialog = 0;
 }

 TorrentView::TorrentView(QWidget *parent)
     : QTreeWidget(parent)
 {
     setAcceptDrops(true);
 }

 void TorrentView::dragMoveEvent(QDragMoveEvent *event)
 {
     // Accept file actions with a '.torrent' extension.
     QUrl url(event->mimeData()->text());
     if (url.isValid() && url.scheme().toLower() == "file"
             && url.path().toLower().endsWith(".torrent"))
         event->acceptProposedAction();
 }

 void TorrentView::dropEvent(QDropEvent *event)
 {
     // Accept drops if the file has a '.torrent' extension and it
     // exists.
     QString fileName = QUrl(event->mimeData()->text()).path();
     if (QFile::exists(fileName) && fileName.toLower().endsWith(".torrent"))
         emit fileDropped(fileName);
 }

 #include "mainwindow.moc"