Web request with progress bar - c++

Question

This is my code (C++: Qt) for getting webpage source:
QString htmlString;
QEventLoop eventLoop;
QNetworkAccessManager mgr;
QObject::connect(&mgr, SIGNAL(finished(QNetworkReply*)), &eventLoop, SLOT(quit()));
QNetworkRequest req( QUrl( QString( "http://stackoverflow.com" ) ) );
QNetworkReply *reply = mgr.get(req);
eventLoop.exec();
htmlString = reply->readAll();
Is there any way to get webpage source with progress bar ?!

Answer 1

Write special class for this:
#ifndef DOWNLOADER_H
#define DOWNLOADER_H
#include <QObject>
#include <QNetworkAccessManager>
#include <QNetworkRequest>
#include <QNetworkReply>
#include <QUrl>
#include <QDebug>
#include <QProgressBar>
class Downloader : public QObject
{
Q_OBJECT
public:
explicit Downloader(QObject *parent = 0);
void doDownload();
public slots:
void replyFinished (QNetworkReply *reply);
void updateDownloadProgress(qint64, qint64);
private:
QNetworkAccessManager *manager;
QProgressBar *bar;
};
#endif
Cpp:
Downloader::Downloader(QObject *parent) :
QObject(parent)
{
}
void Downloader::doDownload()
{
manager = new QNetworkAccessManager(this);
connect(manager, SIGNAL(finished(QNetworkReply*)),
this, SLOT(replyFinished(QNetworkReply*)));
QNetworkReply * rep = manager->get(QNetworkRequest(QUrl("http://qt-project.org/")));
connect(rep, SIGNAL(downloadProgress(qint64, qint64)),
this, SLOT(updateDownloadProgress(qint64, qint64)));
bar = new QProgressBar;
bar->show();
}
void Downloader::replyFinished (QNetworkReply *reply)
{
if(reply->error())
{
qDebug() << "ERROR!";
qDebug() << reply->errorString();
}
else
{
qDebug() << reply->readAll();
}
reply->deleteLater();
}
void Downloader::updateDownloadProgress(qint64 read, qint64 total)
{
qDebug() << read << total;
bar->setMaximum(total);
bar->setValue(read);
}
Usage:
Downloader down;
down.doDownload();
Main idea here is to use void QNetworkReply::downloadProgress(qint64 bytesReceived, qint64 bytesTotal) [signal] to get progress and show this progress in QProgressBar.
And you can do this with your current code without class:
QString htmlString;
QEventLoop eventLoop;
QNetworkAccessManager mgr;
QObject::connect(&mgr, SIGNAL(finished(QNetworkReply*)), &eventLoop, SLOT(quit()));
QProgressBar *bar = new QProgressBar;
bar->show();
QNetworkRequest req( QUrl( QString( "http://stackoverflow.com" ) ) );
QNetworkReply *reply = mgr.get(req);
QObject::connect(reply,&QNetworkReply::downloadProgress,[=](qint64 bytesReceived, qint64 bytesTotal) {//with lambda
bar->setMaximum(bytesTotal);
bar->setValue(bytesReceived);
});
eventLoop.exec();
htmlString = reply->readAll();
qDebug() << htmlString;
I used here C++11 (CONFIG += c++11 to .pro file) and new syntax of signals and slots.