avoiding drawing tiny objects in foocanvas

[Rob Clack <rnc sanger ac uk>]

I'm drawing tens of thousands of rectangles, using foocanvas to 
(successfully - thanks Jody!) speed things up, but when zooming out I 
would like there to come a time when rectangles too small to be 
correctly rendered are not drawn at all.

At present there seems to be a minimum size beyond which they don't 
shrink, so eventually they all merge into each other.  It's as though 
the code says "OK, this is as small as this one gets" and keeps drawing 
it that size, whatever the zoom factor.  I want it to say "This one's 
too small to bother with, so I won't draw it at all"

I accept I'm going to have to hack the foocanvas source code, but so far 
can't find where it is that this decision is being made.

Anyone know where I should be looking?

Thanks
Rob
--
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 Junk is something you've kept for years and then throw away three weeks
 before you need it.
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 Rob Clack                        Acedb Development,  Informatics Group
 email: rnc sanger ac uk                Wellcome Trust Sanger Institute
 Tel: +44 1223 494883                   Wellcome Trust Genome Campus
 Fax: +44 1223 494919                   Hinxton  Cambridge    CB10 1SA