New file downloader class

src/QGCFileDownload.cc

+/*=====================================================================
+
+ QGroundControl Open Source Ground Control Station
+ 
+ (c) 2009, 2015 QGROUNDCONTROL PROJECT <http://www.qgroundcontrol.org>
+ 
+ This file is part of the QGROUNDCONTROL project
+ 
+ QGROUNDCONTROL is free software: you can redistribute it and/or modify
+ it under the terms of the GNU General Public License as published by
+ the Free Software Foundation, either version 3 of the License, or
+ (at your option) any later version.
+ 
+ QGROUNDCONTROL is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ GNU General Public License for more details.
+ 
+ You should have received a copy of the GNU General Public License
+ along with QGROUNDCONTROL. If not, see <http://www.gnu.org/licenses/>.
+ 
+ ======================================================================*/
+
+#include "QGCFileDownload.h"
+
+#include <QFileInfo>
+#include <QStandardPaths>
+
+QGCFileDownload::QGCFileDownload(QObject* parent)
+    : QNetworkAccessManager(parent)
+{
+
+}
+
+bool QGCFileDownload::download(const QString& remoteFile)
+{
+    if (remoteFile.isEmpty()) {
+        qWarning() << "downloadFile empty";
+        return false;
+    }
+    
+    // Split out filename from path
+    QString remoteFileName = QFileInfo(remoteFile).fileName();
+    if (remoteFileName.isEmpty()) {
+        qWarning() << "Unabled to parse filename from downloadFile" << remoteFile;
+        return false;
+    }
+
+    // Determine location to download file to
+    QString localFile = QStandardPaths::writableLocation(QStandardPaths::TempLocation);
+    if (localFile.isEmpty()) {
+        localFile = QStandardPaths::writableLocation(QStandardPaths::DownloadLocation);
+        if (localFile.isEmpty()) {
+            qDebug() << "Unabled to find writable download location. Tried downloads and temp directory.";
+            return false;
+        }
+    }
+    localFile += "/"  + remoteFileName;
+
+    QUrl remoteUrl;
+    if (remoteFile.startsWith("http:")) {
+        remoteUrl.setUrl(remoteFile);
+    } else {
+        remoteUrl = QUrl::fromLocalFile(remoteFile);
+    }
+    if (!remoteUrl.isValid()) {
+        qWarning() << "Remote URL is invalid" << remoteFile;
+        return false;
+    }
+    
+    QNetworkRequest networkRequest(remoteUrl);
+    
+    // Store local file location in user attribute so we can retrieve when the download finishes
+    networkRequest.setAttribute(QNetworkRequest::User, localFile);
+    
+    QNetworkReply* networkReply = get(networkRequest);
+    if (!networkReply) {
+        qWarning() << "QNetworkAccessManager::get failed";
+        return false;
+    }
+
+    connect(networkReply, &QNetworkReply::downloadProgress, this, &QGCFileDownload::downloadProgress);
+    connect(networkReply, &QNetworkReply::finished, this, &QGCFileDownload::_downloadFinished);
+    connect(networkReply, SIGNAL(error(QNetworkReply::NetworkError)), this, SLOT(_downloadError(QNetworkReply::NetworkError)));
+
+    return true;
+}
+
+void QGCFileDownload::_downloadFinished(void)
+{
+    QNetworkReply* reply = qobject_cast<QNetworkReply*>(QObject::sender());
+    
+    // When an error occurs or the user cancels the download, we still end up here. So bail out in
+    // those cases.
+    if (reply->error() != QNetworkReply::NoError) {
+        return;
+    }
+    
+    // Download file location is in user attribute
+    QString downloadFilename = reply->request().attribute(QNetworkRequest::User).toString();
+    Q_ASSERT(!downloadFilename.isEmpty());
+    
+    // Store downloaded file in download location
+    QFile file(downloadFilename);
+    if (!file.open(QIODevice::WriteOnly)) {
+        emit error(QString("Could not save downloaded file to %1. Error: %2").arg(downloadFilename).arg(file.errorString()));
+        return;
+    }
+    
+    file.write(reply->readAll());
+    file.close();
+
+    emit downloadFinished(reply->url().toString(), downloadFilename);
+}
+
+/// @brief Called when an error occurs during download
+void QGCFileDownload::_downloadError(QNetworkReply::NetworkError code)
+{
+    QString errorMsg;
+    
+    if (code == QNetworkReply::OperationCanceledError) {
+        errorMsg = "Download cancelled";
+    } else {
+        errorMsg = QString("Error during download. Error: %1").arg(code);
+    }
+
+    emit error(errorMsg);
+}

src/QGCFileDownload.h

+/*=====================================================================
+ 
+ QGroundControl Open Source Ground Control Station
+ 
+ (c) 2009, 2015 QGROUNDCONTROL PROJECT <http://www.qgroundcontrol.org>
+ 
+ This file is part of the QGROUNDCONTROL project
+ 
+ QGROUNDCONTROL is free software: you can redistribute it and/or modify
+ it under the terms of the GNU General Public License as published by
+ the Free Software Foundation, either version 3 of the License, or
+ (at your option) any later version.
+ 
+ QGROUNDCONTROL is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ GNU General Public License for more details.
+ 
+ You should have received a copy of the GNU General Public License
+ along with QGROUNDCONTROL. If not, see <http://www.gnu.org/licenses/>.
+ 
+ ======================================================================*/
+
+#ifndef QGCFileDownload_H
+#define QGCFileDownload_H
+
+#include <QNetworkReply>
+
+class QGCFileDownload : public QNetworkAccessManager
+{
+    Q_OBJECT
+    
+public:
+    QGCFileDownload(QObject* parent = NULL);
+    
+    /// Download the specified remote file.
+    ///     @param remoteFile File to download. Can be http address or file system path.
+    /// @return true: Asynchronous download has started, false: Download initialization failed
+    bool download(const QString& remoteFile);
+
+signals:
+    void downloadProgress(qint64 curr, qint64 total);
+    void downloadFinished(QString remoteFile, QString localFile);
+    void error(QString errorMsg);
+
+private slots:
+    void _downloadFinished(void);
+    void _downloadError(QNetworkReply::NetworkError code);
+};
+
+#endif