how to hide QgraphicsItem !!!

[peace_comp]

Hi..
I have a problem of how to use correcty the QGraphicsItemGroup ..
well. my application is about zooming on a map .. so depending on the zoom I should display or hide some details..
for example to put the names of cities after zooming I used:

void myview::zoomingin(){
 
for (int i=0;i<5;i++){
QGraphicsTextItem * txt=new  QGraphicsTextItem(citiesName[i]);
txt->setPos(citiesX[i],citiesY[i]);
scene->addItem(txt);
group->addToGroup(txt);
  }
graphicsView->scale(1.2,1.2);
}

void myview::zoomingin(){

for (int i=0;i<5;i++){
QGraphicsTextItem * txt=new  QGraphicsTextItem(citiesName[i]);
txt->setPos(citiesX[i],citiesY[i]);
scene->addItem(txt);
group->addToGroup(txt);
  }
graphicsView->scale(1.2,1.2);
}

To copy to clipboard, switch view to plain text mode 

>> citiesName,citiesX,citiesY are QList containin' the names and coordonates of each citie..

then I should hide them when we zoom out .. I try to used:

void myview::zoomingout(){
 
     scene->destroyItemGroup(group);
 
     graphicsView->scale(1/1.2,1/1.2);
     }

void myview::zoomingout(){
   
     scene->destroyItemGroup(group);
  
     graphicsView->scale(1/1.2,1/1.2);
     }

To copy to clipboard, switch view to plain text mode 

but it doesnt work .. nd when the group became empty it stucks!!

plz if someOne have a idea !!!!!!!!!!!!!!!!!!!!!!

[init2null]

Hello peace_comp, here's a quote from the docs about destroyItemGroup:

void QGraphicsScene::destroyItemGroup ( QGraphicsItemGroup * group )
Reparents all items in group to group's parent item, then removes group from the scene, and finally deletes it. The items' positions and transformations are mapped from the group to the group's parent.

So it sounds like you'll need to delete each label individually. If you want to keep using an ItemGroup, just loop through its childItems() and delete them individually before removing the group.

Hope this helps,

Wesley

[aamer4yu]

well, see the 40000 chip demo,,, they hide details depending on zoom level, It might help u.

Also based on zoom level, u can emit a signal from the scene to some handler class. In the handler class, hide the graphic items u want to hide