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Subject: another clarification needed

CGM Open Members --

Nothing like writing a test suite to flush out the language of the spec!

Here is another question.  I hope and expect that the answer to this one is 
non-controversial.  The text of 'grobject' (, about picking 
*without* a 'region' APS attribute, says:

"a click on non-transparent areas of the graphical elements of the object 
selects the object"

I believe that our wording is sloppy and we mean this to include the cases 
of filled-area objects with:

1. hollow interior style and non-transparent fill color;
2. or empty interior style with a non-transparent edge.

i.e., picking within the interior of a filled-area object with a visible 
(non-transparent) boundary or edge.

Example.   b/w drawing with a CGM "circle" element, drawn with default 
(hollow) interior style and black fill color on a white 
background.  Picking on the interior would select the object?  I think the 
answer is "yes".  If the answer is "no", then one could achieve the result 
by setting interior style to solid, white.  It would look identical 
(assuming that nothing had been drawn behind).

I seem to remember discussion of this in the past.  If the answer is "no", 
then we start to get onto a slippery slope about things that are visible, 
things that are transparent, things that are "camouflaged" (solid but in 
background color), and things like the above that are part visible, part 
transparent or camouflaged.  (And everyone's "pick" algorithms get very 

Does everyone agree that the answer is: "yes", a hollow or empty 
filled-area object with visible boundary or edge is picked by clicking in 
the interior?


p.s.  I do recall, that we do *not* want it to include the cases of line 
primitives which happen to form something that looks like a polygonal or 
solid object.  I.e., if it is line primitives, and not within a Closed 
Figure, then you must pick on the lines.

Lofton Henderson
1919 Fourteenth St., #604
Boulder, CO   80302

Phone:  303-449-8728
Email:  lofton@rockynet.com

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