Grabbing all QGraphicItems current viewable in a QGraphicView

Curtis M. Humphrey — Tue, 07 Apr 2009 18:14:09 +0000

The best way to get a list of all items current displayed inside the QGraphicsView is done through the combination of three steps:

get viewing rectangle
get items intersecting or inside rectangle
check for visibility

QList<QGraphicsItem* > viewItems = m_pView->items(m_pView->rect());
 
for(int i=0; i < viewItems.size(); ++i) {
	if(viewItems.at(i)->isVisible()) {
		//payload
	}
}

Do not use other rectangle functions like sceneRect(), childrenRect(), contentsRect(), etc… as they will not give you the correct bounding region. Also this operation returns all items, so one must check for visibility manually and cast points to any derived class as appropriate.

With casting

QList<QGraphicsItem* > viewItems = m_pView->items(m_pView->rect());
NewType *newType;
 
for(int i=0; i < viewItems.size(); ++i) {
	if(viewItems.at(i)->isVisible()) {
		newType = dynamic_cast<NewType *> (viewItems[i]);
		if(newType != NULL) {
			//payload
		}
	}
}

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Grabbing all QGraphicItems current viewable in a QGraphicView