Qt 5.6 | Qt Network | Torrent Example | mainwindow.cpp Example File

Qt 5.6.3 Reference Documentation

# mainwindow.cpp Example File

torrent/mainwindow.cpp

      /****************************************************************************
      **
      ** 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 <QtWidgets>

      #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);

      #ifndef QT_NO_DRAGANDDROP
      signals:
          void fileDropped(const QString &fileName);

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

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

          void paint(QPainter *painter, const QStyleOptionViewItem &option,
                     const QModelIndex &index ) const Q_DECL_OVERRIDE
          {
              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::asprintf("%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()));

      #ifdef Q_OS_OSX
          setUnifiedTitleAndToolBarOnMac(true);
      #endif

          // 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("QtProject", "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("QtProject", "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);
          const QString num = QString::asprintf("%.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);
          const QString num = QString::asprintf("%.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::asprintf("%4d", rate)));
          RateController::instance()->setUploadLimit(rate * 1024);
      }

      void MainWindow::setDownloadLimit(int value)
      {
          int rate = rateFromValue(value);
          downloadLimitLabel->setText(tr("%1 KB/s").arg(QString::asprintf("%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)
      {
      #ifndef QT_NO_DRAGANDDROP
          setAcceptDrops(true);
      #endif
      }

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

      #include "mainwindow.moc"