qt: unable to read image from url - qt

Question

I have two list of images to be downloaded from network. I use qnetworkaccessmanager to get image from url. But on the reply slot there is no image data with the reply. :( I am not able to figure out where am I going wrong.. If someone is able to figure out, it would be helpful :)
void SyncDialog::getImages()
{
qDebug() << Q_FUNC_INFO << "Invoked";
int groupMasterCount = mSyncMasterData.groupMasterList.count();
qDebug() << Q_FUNC_INFO << "groupmastercout" << groupMasterCount;
for (int i = 0 ; i < groupMasterCount; ++i)
{
GroupMaster groupItem = mSyncMasterData.groupMasterList.at(i);
QNetworkReply *reply =
mImageGetNwMgr.get(QNetworkRequest(QUrl(groupItem.image)));
reply->setProperty("name", QVariant("G_" + groupItem.groupCode));
connect(reply, SIGNAL(readyRead()), this, SLOT(saveImage()));
qDebug() << Q_FUNC_INFO << "get call reply" << reply->readAll();
qDebug() << Q_FUNC_INFO << "get url" << groupItem.image;
mSyncMasterData.groupMasterList[i].image.clear();
#ifdef Q_OS_WIN
mSyncMasterData.groupMasterList[i].image = "C:/POS/Images/G_"
+groupItem.groupCode;
#else
mSyncMasterData.groupMasterList[i].image = "/mnt/sdcard/POS/Images/G_"
+groupItem.groupCode;
#endif
}
int itemMasterCount = mSyncMasterData.itemMasterList.count();
qDebug() << Q_FUNC_INFO << "itemmastercout" << itemMasterCount;
for (int i = 0 ; i < itemMasterCount; ++i)
{
ItemMaster item = mSyncMasterData.itemMasterList.at(i);
QNetworkReply *reply =
mImageGetNwMgr.get(QNetworkRequest(QUrl(item.imagePath)));
reply->setProperty("name", QVariant("I_" + item.itemCode));
connect(reply, SIGNAL(readyRead()), this, SLOT(saveImage()));
qDebug() << Q_FUNC_INFO << "get call reply" << reply->readAll();
qDebug() << Q_FUNC_INFO << "get url" << item.imagePath;
mSyncMasterData.itemMasterList[i].imagePath.clear();
#ifdef Q_OS_WIN
mSyncMasterData.itemMasterList[i].imagePath = "C:/POS/Images/I_"
+item.itemCode;
#else
mSyncMasterData.itemMasterList[i].imagePath = "/mnt/sdcard/POS/Images/G_"
+item.itemCode;
#endif
}
qDebug() << Q_FUNC_INFO << "Exits";
}
In my slot I save images , but in reply->readAll gives me ""
void SyncDialog::saveImage()
{
qDebug() << Q_FUNC_INFO << "Invoked";
QObject *senderObj = sender();
QNetworkReply *reply = qobject_cast<QNetworkReply*>(senderObj);
QImage* img2 = new QImage();
img2->loadFromData(reply->readAll());
qDebug() << Q_FUNC_INFO << "image nw reply" << reply->readAll();
QString imageName = reply->property("name").toString();
qDebug() << Q_FUNC_INFO << "imageName" << imageName;
if(img2->isNull())
{
qDebug() << Q_FUNC_INFO << "image is null";
return;
}
#ifdef Q_OS_WIN
img2->save("C:/POS/Images/" + imageName);
#else
img2->save("/mnt/sdcard/POS/Images/" + imageName);
#endif
qDebug() << Q_FUNC_INFO << "Exits";
}
Also I see in logs "libpng error: Read Error" and the slot is invoked multiple times...

Answer 1

Thanks all,
I resolved the issue with few changes :)
connect(reply, SIGNAL(finished()), this, SLOT(saveImage()));
finished() makes sure complete image data is received from n/w.
QByteArray imageData = reply->readAll();
QImage *image = new QImage();
image->loadFromData(imageData);
reply->readAll() should be saved as first call clears the data after returning it.
image->save("C:/POS/Images/" + imageName + ".png"
don't forget to specify image format (either in filename or as parameter)