On 2011-04-08 at 11:21, Jake Knickerbocker wrote:
> Emmanuele Bassi さんは書きました:
> >there are hints on how to implement actors that can potentially display
> >large collections:
> >
> >
> >  • do not try to paint actors for items that are offscreen;
> 
> 
> Would setting clipping on a parent group accomplish this?  If I say clipped
> to the size of the stage?

no. clipping has nothing to do with not invoking paint: it just means
that the geometry and state data you just spent time pushing to the
GPU will be discarded. the real advantage is to avoid painting in the
first place.

> >  • try to minimize the text computations by avoiding measuring
> >    text multiple times;
> 
> 
> Could you elaborate on this one a little?  What do you mean by "measuring
> text"?  I'm specifically having issues with text.

every operation that involves changing a PangoLayout, or asking its size
after modifying it, will cause Pango to measure the text inside the
layout. do measuring once, and try to cache as much as possible.
ClutterText already does caching internally - but if you change the
properties of ClutterText and cause many relayouts, you'll end up
measuring the text too many times.

one option in a long list of tabular or list text is to avoid causing
relayouts, and when that happens, try to only allocate the actors that
will end up affecting the visible area.

ciao,
 Emmanuele.

-- 
Emmanuele Bassi,
Intel Open Source Technology Center
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