Thread: [Goocanvas-devel] Continual Redrawing of Custom Canvas Item
Status: Beta
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From: Brandon L. <bra...@be...> - 2008-11-04 20:52:23
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While working on a custom canvas item in python, I noticed that the do_simple_create_path method is being called not just when the item changes, but every time a pointer event is sent to the object. This seems rather wasteful...is it a bug in goocanvas, the python bindings, or my code? If it's not a bug, what's the justification? --Brandon |
From: Gustavo J. A. M. C. <gj...@in...> - 2008-11-04 23:00:28
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On Tue, 2008-11-04 at 12:52 -0800, Brandon Lewis wrote: > While working on a custom canvas item in python, I noticed that the > do_simple_create_path method is being called not just when the item > changes, but every time a pointer event is sent to the object. This > seems rather wasteful...is it a bug in goocanvas, the python bindings, > or my code? If it's not a bug, what's the justification? Goocanvas needs to know the path your item will create in order to perform hit testing. I suppose if you do not need hit testing then you could set pointer-events to 0 and goocanvas "should" stop calling it. Additionally, if you set the property 'clip-path' on your item, goocanvas will use the value of this property instead of calling your code every time. This is new to me, and a conclusion from quickly glancing over the code, so I could be wrong. > > --Brandon > > ------------------------------------------------------------------------- > This SF.Net email is sponsored by the Moblin Your Move Developer's challenge > Build the coolest Linux based applications with Moblin SDK & win great prizes > Grand prize is a trip for two to an Open Source event anywhere in the world > http://moblin-contest.org/redirect.php?banner_id=100&url=/ > _______________________________________________ > Goocanvas-devel mailing list > Goo...@li... > https://lists.sourceforge.net/lists/listinfo/goocanvas-devel -- Gustavo J. A. M. Carneiro <gj...@in...> <gu...@us...> "The universe is always one step beyond logic" -- Frank Herbert |
From: Damon C. <da...@ka...> - 2008-11-05 00:12:08
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On Tue, 2008-11-04 at 12:52 -0800, Brandon Lewis wrote: > While working on a custom canvas item in python, I noticed that the > do_simple_create_path method is being called not just when the item > changes, but every time a pointer event is sent to the object. This > seems rather wasteful...is it a bug in goocanvas, the python bindings, > or my code? If it's not a bug, what's the justification? GooCanvas has to keep track of which item the pointer is over, so it can send all sorts of events to the items at appropriate times - enter-notify, leave-notify, motion-notify, etc. I'm not sure if it is a performance issue. Slow redrawing seems more of a problem. Damon |