QGraphicsItem's paintEngine changed during program runing

[TZQQ]

Hi guys,

To speed up the QGraphicView system, I render it with OpenGL, set the Viewer's viewport to GLWidget:

setViewport(new QGLWidget(QGLFormat(QGL::DoubleBuffer)));

In the GraphicItem paint function, monitor the paintEngine:

void Item::paint(QPainter *painter, const QStyleOptionGraphicsItem *option, QWidget *widget)
	{
		QWidget* vp = scene()->views().front()->viewport();
		QGLWidget* glw = qobject_cast<QGLWidget*>(vp);
		//qDebug() << "viewport" << glw->format();
		qDebug() << this->parent() << this->parentItem();

		bool ok = false;
		int type = painter->paintEngine()->type();
		if (type == QPaintEngine::OpenGL2)
			ok = true;

		qDebug() << (int)this << type;
}

In the debug output information, at first the type is 14(GL2), after some operation(diffcult to analsys), the output change to 10(Raster).

Any suggestion for debug?

[TZQQ]

Update： the widget changed to 0x0 rather than the QGLWidget when problem occurs.

[SGaist]

Hi and welcome to devnet,

Which version of Qt are you using ? On which OS ?

[TZQQ]

@SGaist
Qt5.5-msvc2013
Win 10

[SGaist]

Can you use a more recent version ?
Also note that QGLWidget has been deprecated for QOpenGLWidget.