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.