Hiding QGraphicsRectItems

[ddze]

I am trying to use hide() show() or setVisible(false) function with QGraphicsRectItem objects. I can display them on the scene but no way I can do anything to hide them from screen. I have initialised them in the following code :

rectItems = new QVector<QGraphicsRectItem *>();
 
for (int raw=0;raw<this->qElementsHeight;raw++){
		for(int column=0;column<this->qElementsWidth;column++){
			QRectF rectF( raw*48, column*48, 48, 48 );
			QGraphicsRectItem *rect = new QGraphicsRectItem(rectF);
			rect->setPen(pen);
			rectItems->push_back(rect);
			rectItems->last()->setVisible(false);
			this->addRect(rectItems->last()->rect(),pen);
		}
	}

rectItems = new QVector<QGraphicsRectItem *>();

for (int raw=0;raw<this->qElementsHeight;raw++){
		for(int column=0;column<this->qElementsWidth;column++){
			QRectF rectF( raw*48, column*48, 48, 48 );
			QGraphicsRectItem *rect = new QGraphicsRectItem(rectF);
			rect->setPen(pen);
			rectItems->push_back(rect);
			rectItems->last()->setVisible(false);
			this->addRect(rectItems->last()->rect(),pen);
		}
	}

To copy to clipboard, switch view to plain text mode 

then tried to use hide() in a slot function:

for (int c=0;c<rectItems->count();c++){
		QGraphicsRectItem *temp =rectItems->at(c);
		if(bGrid) {
			//temp->setVisible(true);
			//temp->show();
			rectItems[0].at(c)->setVisible(true);
		}
		else {
			//temp->setVisible(false);
			//temp->hide();
			rectItems[0].at(c)->setVisible(false);
		}
	}

for (int c=0;c<rectItems->count();c++){
		QGraphicsRectItem *temp =rectItems->at(c);
		if(bGrid) {
			//temp->setVisible(true);
			//temp->show();
			rectItems[0].at(c)->setVisible(true);
		}
		else {
			//temp->setVisible(false);
			//temp->hide();
			rectItems[0].at(c)->setVisible(false);
		}
	}

To copy to clipboard, switch view to plain text mode 

none of it hides the rectangles in the scene. Is there a way of hiding them ?

[wysota]

Your code shouldn't even compile. Please check it out.
It should probably be:

rectItems[i]->hide();

rectItems[i]->hide();

To copy to clipboard, switch view to plain text mode 

[ddze]

Well it compiles perfectly.

QVector<QGraphicsRectItem *> *rectItems;

[Lykurg]

First please reconsider what wysota has told you:

rectItems[0].at(c)

rectItems[0].at(c)

To copy to clipboard, switch view to plain text mode 

won't work like you expect it, second your pointer are all meaningless. Why? Because addRect() creates new items which are added to the scene. You have to store the pointers addRect() returns or simply use addItem().

[ddze]

Why should I consider wysota ?

This is corrected code with little bit of mix pointer formats for him and you revising your comments.

Correct Code:

void QSystem::drawGrid() {
	bGrid=!bGrid;
	for (int c=0;c<rectItems->count();c++){
		if(bGrid) {rectItems->at(c)->show();}
		else {rectItems[0].at(c)->hide();}
	}
}

void QSystem::drawGrid() {
	bGrid=!bGrid;
	for (int c=0;c<rectItems->count();c++){
		if(bGrid) {rectItems->at(c)->show();}
		else {rectItems[0].at(c)->hide();}
	}
}

To copy to clipboard, switch view to plain text mode 

Correct addRect:

QGraphicsRectItem *rect=this->addRect(rectF,pen);

QGraphicsRectItem *rect=this->addRect(rectF,pen);

To copy to clipboard, switch view to plain text mode 

My mistake : I was in rush and did not read the QT Class QGraphicsScene addRect properly.
QGraphicsRectItem * QGraphicsScene::addRect ( const QRectF & rect, const QPen & pen = QPen(), const QBrush & brush = QBrush() )
I have mistakenly used QGraphicsRectItem instead of QRectF.

Wrong:

this->addRect(rectItems->last()->rect(),pen);

this->addRect(rectItems->last()->rect(),pen);

To copy to clipboard, switch view to plain text mode