View source for Download Data from URL

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[[Category:Snippets]]
[[Category:Tutorial]]
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<div style="float:left;padding:14px;">__TOC__</div>

'''English''' [[Download_Data_from_URL_Bulgarian|Български]] [[Download_Data_from_URL_Korean|한국어]][[Download_Data_from_URL_Persian|فارسی]]

== Download Data from URL ==

The following code snippet demonstrates how to download data as {{DocLink|QBteArray}} from URL. The downloaded data can be saved as a file or converted to appropriate object. For example if an image is downloaded it can be converted to {{DocLink|QPixmap}} or {{DocLink|QImage}} using method [http://doc.qt.io/qt-5/qimage.html#loadFromData loadFromData()]

Please note that although the name of the class is FileDownloader the downloaded data is not saved on the disk as file!

== Important Classes ==

* {{DocLink|QNetworkAccessManager}}
* {{DocLink|QNetworkRequest}}
* {{DocLink|QNetworkReply}}
* {{DocLink|QUrl}}

== .pro File ==

<code>
QT ''= network
</code>

If you are targeting Symbian devices remember to add the capability for network services.

<code>
symbian:TARGET.CAPABILITY''= NetworkServices
</code>

== filedownloader.h ==

<code>
#ifndef FILEDOWNLOADER_H
#define FILEDOWNLOADER_H

#include <QObject>
#include <QByteArray>
#include <QNetworkAccessManager>
#include <QNetworkRequest>
#include <QNetworkReply>

class FileDownloader : public QObject
{
 Q_OBJECT
public:
 explicit FileDownloader(QUrl imageUrl, QObject '''parent = 0);

 virtual ~FileDownloader();

 QByteArray downloadedData() const;

signals:
 void downloaded();

private slots:

 void fileDownloaded(QNetworkReply''' pReply);

private:

QNetworkAccessManager m_WebCtrl;

QByteArray m_DownloadedData;

};

#endif // FILEDOWNLOADER_H
</code>

== filedownloader.cpp ==

<code>
#include "filedownloader.h"

FileDownloader::FileDownloader(QUrl imageUrl, QObject '''parent) :
 QObject(parent)
{
 connect(&amp;m_WebCtrl, SIGNAL (finished(QNetworkReply*)),
 SLOT (fileDownloaded(QNetworkReply*)));

 QNetworkRequest request(imageUrl);
 m_WebCtrl.get(request);
}

FileDownloader::~FileDownloader()
{

}

void FileDownloader::fileDownloaded(QNetworkReply''' pReply)
{
 m_DownloadedData = pReply->readAll();
 //emit a signal
 pReply->deleteLater();
 emit downloaded();
}

QByteArray FileDownloader::downloadedData() const
{
 return m_DownloadedData;
}
</code>

= Usage =

== Load Pixmap from URL ==

* Declare slot

<code>
private slots:

void loadImage();
</code>

* Connect signal '''downloaded()''' to the slot

<code>
QUrl imageUrl("http://qt.digia.com/Documents/1/QtLogo.png");
m_pImgCtrl = new FileDownloader(imageUrl, this);

connect(m_pImgCtrl, SIGNAL (downloaded()), SLOT (loadImage()));
</code>

* Load QPixmap from the downloaded data

<code>
void MainWindow::loadImage()
{
 QPixmap buttonImage;
 buttonImage.loadFromData(m_pImgCtrl->downloadedData());
}
</code>