How to avoid calling boundingRect() & shape()

[marcel]

Well, bitto suggested in a similar post to increase the scene's bspTreeDepth property. If you try this, make sure first that itemIndexMethod is BspTreeIndex.

[nileshsince1980]

By default item index method is BspTreeIndex, but as I want to move rectangles and lines adjoined it, it becomes very slow .
Can you suggest any other method so that I can use to rendering.
Also loading time is also too slow. How we can add items in Scene fastly & render it ?

[marcel]

By default item index method is BspTreeIndex, but as I want to move rectangles and lines adjoined it, it becomes very slow .
Can you suggest any other method so that I can use to rendering.
Also loading time is also too slow. How we can add items in Scene fastly & render it ?

Have you increased bspTreeDepth?

[nileshsince1980]

how to set setBspTreeDepth property for scene items ???
Also I have tried setViewport(new OpenGLWidget) but it slowa down rendering,
Is there is another way to make fast rendering ??

[Gopala Krishna]

http://labs.trolltech.com/page/Proje...ys/DevDays2007
The gv presentation might give you some tips to improve rendering speed.

Have you cached the values to be returned in boundingRect() and shape() ? Probably you can inline them..

Also have you profiled your app and tried to find out where exactly it is being slow ?

P.S: Did you try out all the suggestions mentioned in the previous threads in this forum ?

[Brandybuck]

I have had cases where NoIndex was significantly faster than BspTreeIndex. If not, play around with bspTreeDepth().

Gopala's suggestion to cache bounding rects and shapes is also a good one. Most of the examples show calculating rects and shapes on the fly, but this is not good. Put a QRectF and a QPainterPath member in your item, and return them when requested. Also keep your shapes simple. Sometimes a loose approximation of the shape is sufficient.