Re: GnomeCanvasGroups?

[Lauris Kaplinski <lauris ximian com>]

Hello!

They are used both for management and optimization:
1. Group serves as handle for collection of items, allowing you to
transfrom (move, scale, rotate...) all these together.
2. Group manages its own binding box, thus speeding up display,
if you have many items. If entire group of items is outside of
region of interest (redraw area), the redraw proceeds to next
object of group level without checking its children one-by-one.
The same stands for determining, which item receives mouse events.

Depending on your application, it is usable to group items:
- semantically (make meta-objects consisting of many small items
   to be groups)
- at least to 1:100 ratio - i.e. no more than 100 children on any level
   - adding more grouping levels, if necessary. If items are very
   complex, you may want to reduce that ratio, if very simple, you
   can have more.

Best wishes,
Lauris Kaplinski


On 05 Apr 2001 17:48:57 -0400, David J. Topper wrote:
> 
> Hi everyone,
> 
> What are these used for?  I assumed it was to be able to group / move
> items together.  But I don't think this is correct.
> 
> Advice / input would be appreciated.
> 
> Thanks,
> 
> DT
> --
> Technical Director, Virginia Center for Computer Music
> http://www.people.virginia.edu/~djt7p
> (804) 924-7355
> 
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