is it possible to using QNetworkAccessManager in subclass of QGraphicsRectItem?

[FkZsd]

Hi everyone,

I have the problem to using QNetworkAccessManager in QGraphicsRectItem.

Here is my code snapshot

ThRect.h

class ThRect : public QObject, public QGraphicsRectItem
{
	Q_OBJECT

public:
	ThRect();
	~ThRect();

	void paint(QPainter *painter, const QStyleOptionGraphicsItem *option, QWidget *widget);

	void mousePressEvent(QGraphicsSceneMouseEvent *e);
	void mouseMoveEvent(QGraphicsSceneMouseEvent *e);
	void hoverEnterEvent(QGraphicsSceneHoverEvent * e);
	void hoverLeaveEvent(QGraphicsSceneHoverEvent * e);

	void Prediction(QImage src);
private:
	QNetworkAccessManager *m_networkManager;

	bool m_ishover = false;
private slots:
	void uploadDone(QNetworkReply*);
};

ThRect.cpp

#include "ThRect.h"
#include <QHttpMultiPart>
#include <QBuffer>
#include <QNetworkReply>
#include <QCoreApplication>

ThRect::ThRect()
	:QObject()
{
	QGraphicsRectItem::QGraphicsRectItem();
	setFlags(QGraphicsItem::ItemSendsGeometryChanges | QGraphicsItem::ItemIsFocusable);
	m_networkManager = new QNetworkAccessManager();
	//-----------------------console output-----------------------------
	//
	//QEventLoop: Cannot be used without QApplication
	//QObject::connect: Cannot connect (null)::aboutToQuit() to QNativeWifiEngine::closeHandle()
	//
	setAcceptHoverEvents(true);
	prepareGeometryChange();
	connect(m_networkManager, SIGNAL(finished(QNetworkReply*)), this, SLOT(uploadDone(QNetworkReply*)));
}

ThRect::~ThRect()
{
	
}

void ThRect::paint(QPainter *painter, const QStyleOptionGraphicsItem *option, QWidget *widget)
{
	//normal
	setPen(QPen(Qt::blue, 4));
	
	//hover
	if (m_ishover)
	{
		setPen(QPen(Qt::cyan, 4));
	}

	//focus
	if (hasFocus())
	{
		setPen(QPen(Qt::yellow, 4));
	}
	QGraphicsRectItem::paint(painter, option, widget);
}

void ThRect::mousePressEvent(QGraphicsSceneMouseEvent *e)
{
	setFocus();
	QGraphicsRectItem::mousePressEvent(e);
}

void ThRect::mouseMoveEvent(QGraphicsSceneMouseEvent *e)
{
	QGraphicsRectItem::mouseMoveEvent(e);
}

void ThRect::hoverEnterEvent(QGraphicsSceneHoverEvent * e)
{
	m_ishover = true;
	QGraphicsRectItem::hoverEnterEvent(e);
}

void ThRect::hoverLeaveEvent(QGraphicsSceneHoverEvent * e)
{
	m_ishover = false;
	QGraphicsRectItem::hoverLeaveEvent(e);
}



void ThRect::Prediction(QImage src)
{
	QRect ROI(this->rect().x(), this->rect().y(), this->rect().width(), this->rect().height());
	QImage img = src.copy(ROI);

	QHttpMultiPart *multiPart = new QHttpMultiPart(QHttpMultiPart::FormDataType);
	QHttpPart imagePart;
	imagePart.setHeader(QNetworkRequest::ContentTypeHeader, QVariant("image/jpeg"));
	imagePart.setHeader(QNetworkRequest::ContentDispositionHeader, QVariant("form-data; name=\"file\"; filename=\"0.jpg\""));
	QByteArray ba;
	QBuffer buffer(&ba);
	buffer.open(QIODevice::WriteOnly);
	img.save(&buffer, "jpg"); // writes image into ba in PNG format
	imagePart.setBody(ba);
	multiPart->append(imagePart);

	QUrl url("http://192.168.1.52:5000/upload");
	QNetworkRequest request(url);

	QNetworkAccessManager *networkManager = new QNetworkAccessManager(this);
	QNetworkReply *reply = networkManager->post(request, multiPart); //Critical error detected c0000374 crash
	qDebug() << QString(multiPart->boundary());
	multiPart->setParent(reply); // delete the multiPart with the reply

	connect(networkManager, SIGNAL(finished(QNetworkReply*)), this, SLOT(uploadDone(QNetworkReply*)));

	
}

void ThCADxRect::uploadDone(QNetworkReply *reply)
{
	//reply->open(QIODevice::ReadOnly);

	//// if the response is correct
	//if (reply->error() == QNetworkReply::NoError)
	//{
	//	QByteArray str = (reply->readAll());
	//	QString response = QString::fromUtf8(str.data(), str.size());
	//	qDebug() << " re " << response;
	//}
	////error sever
	//else
	//	qDebug() << "error response server";
	//qDebug() << reply;
}

Thansks in advance

[jsulm]

@FkZsd From software design point of view it does not make sense to have network functionality inside a GraphicsRectItem.
Also you create a new QNetworkAccessManager in ThRect::Prediction instead of using the one you created in the constructor.

[Pablo J. Rogina]

@FkZsd +1 to the reply from @jsulm but just to better understand your issue, what's your exact error...?

[FkZsd]

Thanks @jsulm and @Pablo-J-Rogina ,
Finally I found the reason. It's caused by wrong lib include.
I'm running at debug mode and using release mode lib.
All I done is change Qt5Network.lib to Qt5Networkd.lib everything is well.

Thanks you guys again.