[Qt-interest] QGraphicsView performance issue

[Alexis Ménard]

On Monday 11 May 2009 17:09:44 Santhosh Y wrote:
> Alexis Ménard wrote:
> > On Monday 11 May 2009 16:10:04 Santhosh Y wrote:
> >> Please read my comments below
> >>
> >> Alexis Ménard wrote:
> >>> On Monday 11 May 2009 15:01:52 Santhosh Y wrote:
> >>>> Santhosh Y wrote:
> >>>>> Hi,
> >>>
> >>> Hi,
> >>>
> >>>>> I added  30,000 items to the scene.
> >>>>> While updating the scene, the response from the view is very slow.
> >>>>>
> >>>>> Among these 30,000 items only 3,000 items have the distinctive
> >>>>> locations and the rest of 27,000 items have the same location of
> >>>>> those 3,000 items.
> >>>>>
> >>>>> In such a scenario to improve the performance, what flags
> >>>>> I should use on the scene to improve the performance.
> >>>
> >>> If the painting (paint method) is slow on items, you can use the cache
> >>> mode, itemCoordinateCache if you have no transformations otherwise
> >>> DeviceCoordinateCache.
> >>
> >> I am not able to find the above flag for setting cache mode.
> >> I am using 4.3.3 version of Qt.
> >> I can use only cacheNone or cacheBackGround.
> >
> > OoOooOOooooOOo. Then i fully encourage you to upgrade to 4.5. Lot of
> > performance improvements has been made since 4.3.3 and those repaint bugs
> > has been
> > probably fixed. And you have more features.
>
> Is 4.5 released for windows version.

Yes and more 4.5.1. As always Qt is cross platform all version are released at 
the same time and it is the same source code anyway.

>
> >>> If you trigger full updates on the scene, then you need to set the
> >>> viewportUpdate to fullviewport update because sometimes it is slower to
> >>> caculate the exact dirty area than repainting the all scene (aka
> >>> OpenGL).
> >>>
> >>>> To add to the above issue, what I have observed is that, paintEvent()
> >>>> on QGraphicsview is being called multiple times
> >>>> which is taking around 3 sec for each call to pick the items from the
> >>>> visible region for sending to
> >>>
> >>> That why we are working on an API to allow you to create your custom
> >>> indexing where you can skip some parts of the scene or skipping items
> >>> that you don't need.
> >>>
> >>>> QGraphicsScene::drawItems(QPainter* p, int numItems, QGraphicsItem**
> >>>> items, const QStyleOptionGraphicsItem* options )
> >>>>  function dispatch.
> >>>>
> >>>> Can anybody tell me how to track from where this paintEvent call is
> >>>> dispatched so many times.
> >>>
> >>> recalculateContentSize can be the source of those calls because you
> >>> query a full update (see below).
> >>>
> >>>> I have no QGraphicsView::update() calls in my code, but I have the
> >>>> QGraphicsScene::update() calls.
> >>>
> >>> Calling update on the scene is not a good idea unless you give a
> >>> rectangle to update(). Without parameter it will redraw everything...
> >>> Why do you need to update the whole scene? Updating the content should
> >>> triggers updates on items for you...
> >>
> >> I removed all the QGraphicsScene::update () calls. Still the performance
> >> have not improved.
> >>
> >>>> But none of the QGraphicsScene::update () call is immediately
> >>>> resulting a QGraphicsView::paintEvent(QPaintEvent*)
> >>>>
> >>>> My observation is that all the mutliple calls on
> >>>> QGraphicsView::paintEvent(QPaintEvent*) are resulting from the
> >>>> following stack.
> >>>> ----------------------------------------------------------------------
> >>>>-- --- ---------------------------
> >>>> QGraphicsView::paintEvent(QPaintEvent * e=0x0012b550)  Line 1282   
> >>>> C++ QtGuid4.dll!QWidget::event(QEvent * event=0x0012b550)  Line 6256  
> >>>>  C++ QtGuid4.dll!QFrame::event(QEvent * e=0x0012b550)  Line 641    C++
> >>>> QtGuid4.dll!QAbstractScrollArea::viewportEvent(QEvent *
> >>>> e=0x0012b550)  Line 909 + 0xc bytes    C++
> >>>>      QtGuid4.dll!QGraphicsView::viewportEvent(QEvent *
> >>>> event=0x0012b550)  Line 2324    C++
> >>>>      QtGuid4.dll!QAbstractScrollAreaPrivate::viewportEvent(QEvent *
> >>>> event=0x0012b550)  Line 78 + 0x28 bytes    C++
> >>>>      QtGuid4.dll!QAbstractScrollAreaFilter::eventFilter(QObject *
> >>>> o=0x08705aa0, QEvent * e=0x0012b550)  Line 89 + 0x29 bytes    C++
> >>>>      QtGuid4.dll!QApplicationPrivate::notify_helper(QObject *
> >>>> receiver=0x08705aa0, QEvent * e=0x0012b550)  Line 3533 + 0x1b bytes
> >>>> C++ QtGuid4.dll!QApplication::notify(QObject * receiver=0x08705aa0,
> >>>> QEvent * e=0x0012b550)  Line 3482 + 0x10 bytes    C++
> >>>>      QtCored4.dll!QCoreApplication::notifyInternal(QObject *
> >>>> receiver=0x08705aa0, QEvent * event=0x0012b550)  Line 516    C++
> >>>>      QtCored4.dll!QCoreApplication::sendSpontaneousEvent(QObject *
> >>>> receiver=0x08705aa0, QEvent * event=0x0012b550)  Line 188 + 0x38
> >>>> bytes    C++
> >>>>      QtGuid4.dll!qt_sendSpontaneousEvent(QObject *
> >>>> receiver=0x08705aa0, QEvent * event=0x0012b550)  Line 1182 + 0xe bytes
> >>>>    C++
> >>>>      QtGuid4.dll!QWidgetPrivate::drawWidget(QPaintDevice *
> >>>> pdev=0x02a0a878, const QRegion & rgn={...}, const QPoint &
> >>>> offset={...}, int flags=4)  Line 1195 + 0xd bytes    C++
> >>>>
> >>>> QtGuid4.dll!QWidgetBackingStore::paintSiblingsRecursive(QPaintDevice *
> >>>> pdev=0x02a0a878, const QList<QObject *> & siblings={...}, int index=0,
> >>>> const QRegion & rgn={...}, const QPoint & offset={...}, int flags=4)
> >>>> Line 1099    C++
> >>>>      QtGuid4.dll!QWidgetPrivate::drawWidget(QPaintDevice *
> >>>> pdev=0x02a0a878, const QRegion & rgn={...}, const QPoint &
> >>>> offset={...}, int flags=4)  Line 1231 + 0x2e bytes    C++
> >>>>
> >>>> QtGuid4.dll!QWidgetBackingStore::paintSiblingsRecursive(QPaintDevice *
> >>>> pdev=0x02a0a878, const QList<QObject *> & siblings={...}, int index=2,
> >>>> const QRegion & rgn={...}, const QPoint & offset={...}, int flags=4)
> >>>> Line 1099    C++
> >>>>
> >>>> QtGuid4.dll!QWidgetBackingStore::paintSiblingsRecursive(QPaintDevice *
> >>>> pdev=0x02a0a878, const QList<QObject *> & siblings={...}, int index=3,
> >>>> const QRegion & rgn={...}, const QPoint & offset={...}, int flags=4)
> >>>> Line 1089 + 0x20 bytes    C++
> >>>>
> >>>> QtGuid4.dll!QWidgetBackingStore::paintSiblingsRecursive(QPaintDevice *
> >>>> pdev=0x02a0a878, const QList<QObject *> & siblings={...}, int index=4,
> >>>> const QRegion & rgn={...}, const QPoint & offset={...}, int flags=4)
> >>>> Line 1089 + 0x20 bytes    C++
> >>>>      QtGuid4.dll!QWidgetPrivate::drawWidget(QPaintDevice *
> >>>> pdev=0x02a0a878, const QRegion & rgn={...}, const QPoint &
> >>>> offset={...}, int flags=4)  Line 1231 + 0x2e bytes    C++
> >>>>
> >>>> QtGuid4.dll!QWidgetBackingStore::paintSiblingsRecursive(QPaintDevice *
> >>>> pdev=0x02a0a878, const QList<QObject *> & siblings={...}, int
> >>>> index=13, const QRegion & rgn={...}, const QPoint & offset={...}, int
> >>>> flags=4) Line 1099    C++
> >>>>      QtGuid4.dll!QWidgetPrivate::drawWidget(QPaintDevice *
> >>>> pdev=0x02a0a878, const QRegion & rgn={...}, const QPoint &
> >>>> offset={...}, int flags=4)  Line 1231 + 0x2e bytes    C++
> >>>>
> >>>> QtGuid4.dll!QWidgetBackingStore::paintSiblingsRecursive(QPaintDevice *
> >>>> pdev=0x02a0a878, const QList<QObject *> & siblings={...}, int index=5,
> >>>> const QRegion & rgn={...}, const QPoint & offset={...}, int flags=4)
> >>>> Line 1099    C++
> >>>>      QtGuid4.dll!QWidgetPrivate::drawWidget(QPaintDevice *
> >>>> pdev=0x02a0a878, const QRegion & rgn={...}, const QPoint &
> >>>> offset={...}, int flags=4)  Line 1231 + 0x2e bytes    C++
> >>>>
> >>>> QtGuid4.dll!QWidgetBackingStore::paintSiblingsRecursive(QPaintDevice *
> >>>> pdev=0x02a0a878, const QList<QObject *> & siblings={...}, int
> >>>> index=40, const QRegion & rgn={...}, const QPoint & offset={...}, int
> >>>> flags=4) Line 1099    C++
> >>>>
> >>>> QtGuid4.dll!QWidgetBackingStore::paintSiblingsRecursive(QPaintDevice *
> >>>> pdev=0x02a0a878, const QList<QObject *> & siblings={...}, int
> >>>> index=41, const QRegion & rgn={...}, const QPoint & offset={...}, int
> >>>> flags=4) Line 1089 + 0x20 bytes    C++
> >>>>
> >>>> QtGuid4.dll!QWidgetBackingStore::paintSiblingsRecursive(QPaintDevice *
> >>>> pdev=0x02a0a878, const QList<QObject *> & siblings={...}, int
> >>>> index=42, const QRegion & rgn={...}, const QPoint & offset={...}, int
> >>>> flags=4) Line 1089 + 0x20 bytes    C++
> >>>>      QtGuid4.dll!QWidgetPrivate::drawWidget(QPaintDevice *
> >>>> pdev=0x02a0a878, const QRegion & rgn={...}, const QPoint &
> >>>> offset={...}, int flags=5)  Line 1231 + 0x2e bytes    C++
> >>>>      QtGuid4.dll!QWidgetBackingStore::cleanRegion(const QRegion &
> >>>> rgn={...}, QWidget * widget=0x0012fd58, bool
> >>>> recursiveCopyToScreen=false)  Line 1000    C++
> >>>>      QtGuid4.dll!qt_syncBackingStore(QRegion rgn={...}, QWidget *
> >>>> widget=0x0012fd58, bool recursive=false)  Line 230    C++
> >>>>      QtGuid4.dll!QETWidget::translatePaintEvent(const tagMSG &
> >>>> msg={...})  Line 3094 + 0x2b bytes    C++
> >>>>      QtGuid4.dll!QtWndProc(HWND__ * hwnd=0x000a1118, unsigned int
> >>>> message=15, unsigned int wParam=0, long lParam=0)  Line 1680 + 0xc
> >>>> bytes    C++
> >>>> ----------------------------------------------------------------------
> >>>>-- --- ---------------------------
> >>>>
> >>>> Please tell me how to track the event call of paint over
> >>>> QGraphicsView.

-- 

Alexis Ménard
Software Engineer, Widgets Team 1
Qt Software, Nokia Norge AS, Sandakerveien 116, 0484 Oslo, Norway
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://lists.qt-project.org/pipermail/qt-interest-old/attachments/20090511/26ea5882/attachment.html