[Qt-interest] setParentItem() is hanging

[trinathpujari]

Hi Andre,

             Thanks for your replies....
             I will elaborate what i am trying to do with my code.

            I have one symbol screen and on the top of that screen, one 
symbol line is there where i will show the symbols which is selected in 
the symbol screen.
            symbol screen as well as symbol line are both derived from 
qgraphicswidget.
            I am creating the symbol line and adding that it to the 
symbol screen, so i can display on the screen at a time.
            And any update to symbol screen automatically updates the 
symbol line also.In this scenario i am using setParentItem( )
            
           And the function where i am using the same is in below, I 
tried to elaborate in the function which line is doing what...
           Hope this will clarify and solve the problem....
           If you have any kind of clarification then please reply me....

> void CPanel::setSymbolMode( )
> {
>            /* Creating the symbol overlay */
>            if ( m_pSymbolOverlay == NULL )
>            {
>                /*Creating the object of SymbolOverlay and screenInfo 
> will hold the geometry of symbol screen*/;
>                SCREEN_SIZE screenInfo = 
> CViewManager::getVM()->getDisplayInfo();
>                m_pSymbolOverlay = new CSymbolOverlay();
>                /*Setting up the geometry for OverlayScreen*/
>                
> m_pSymbolOverlay->setGeometry(screenInfo.apparea.symbolarea_dim.left,
>                                                                       
> screenInfo.apparea.symbolarea_dim.top,
>                                                                       
> width,
>                                                                       
> height);
     /* first we tried this setParentItem,but it was hanging at this 
particular line.
*     m_pSymbolOverlay->setParentItem(m_pSelf); //*m_pSelf is a pointer 
to current screen*//*
 
                         }
/* setParentItem() was hanging so , we tried this alternate way to add 
this symbol screen to the scene*/
           if ( m_pSymbolOverlay != NULL )
           {                             /* Attach and show the symbol 
window */
               // Add CSymbolOverlay to scene
               
if(!CQTSurface::getQTSurface()->m_pScene->items().contains(m_pSymbolOverlay)) 

               {
                  /*Adding Overlay object to the scene*/
                   
CQTSurface::getQTSurface()->m_pScene->addItem(m_pSymbolOverlay);
               }
               m_pSymbolOverlay->setZValue(5);
               m_pSymbolOverlay->setVisible(true);
               m_pSymbolOverlay->show();

           }
        /*repainting the Overlay screen*/
       m_pSymbolOverlay->repaint();
   }
   
Regards
 Trinath



André Somers wrote:
> Warnings in the documentation don't magically show up in the code, or in the
> compiler output. 
> I would like to suggest that you show us what you try to do, with code,
> because there are many users that successfully use QGraphicsView, add items
> to scenes and parents, etc. I guess you're doing something wrong, but it's
> hard to see what if you don't show it to us. 
>
> Note that an "undefined behavior" warning in the documentation is to be
> taken very seriously. You want to stay away from that. Really. Your program
> might end up eating your babies, so to speak. 
>
> André
>
>
> -----Oorspronkelijk bericht-----
> Van: trinathpujari [mailto:trinathpujari at tataelxsi.co.in] 
> Verzonden: donderdag 18 februari 2010 12:41 
> Aan: Andre Somers
> CC: Qt-interest
> Onderwerp: Re: [Qt-interest] setParentItem() is hanging
>
> Hi Andre,
>
> Thanks for your earliest reply....
>             
>              Actually we are now trying to replace 
> QGraphicsItem::setParentItem( ) with QGraphicsScene::addItem(object) 
> which will add the object directly to the scene but this is also not 
> working and regarding your query about warning,
>
>   
>> Calling this function on an item that is an ancestor of parent have 
>>     
> undefined behaviour.
>
> No warning is coming in my code. If you know some alternative solution 
> for the same please help me.
>
> Regards
>  Trinath
>
>
>
> Andre Somers wrote:
>   
>> trinathpujari wrote:
>>   
>>     
>>> Hi All,
>>>       
>>>        When i am using setParentItem(), screen is hanging at the point 
>>> of setParentItem() function call.
>>>        Can anybody tell any other way of implementing the setParentItem( 
>>> ) function.
>>>
>>> Thanking in Advance
>>>
>>> Regards
>>>  Trinath
>>>   
>>>     
>>>       
>> It would have been helpful if you would have given slightly more 
>> context, but I will assume for now that you are refering to 
>> QGraphicsItem::setParentItem, as that seems to be the only function with 
>> that name in Qt.
>>
>> Did you head the warning in the documentation?
>>  > Calling this function on an item that is an ancestor of parent have 
>> undefined behaviour.
>>
>> André
>>
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>>
>>   
>>     
>
>
>
>
>
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