RE: [cgmo-webcgm] temporal/spatial priority and Style Properties

["Weidenbrueck, Dieter" <dweidenbrueck@ptc.com>]

Lofton,

in general any change in appearance will affect a certain area of the
viewer rect. Typically you invalidate this area to mark it up for
redraw.
During redraw everything will be redrawn that intersects the invalidated
area.
There are functions in the OS that support this concept.

So there are at least two ways of getting to a correct representation of
a DOM change like the one you described:
- invalidate the affected areas and redraw those
- redraw all

Regards,
Dieter

-----Original Message-----
From: Lofton Henderson [mailto:lofton@rockynet.com] 
Sent: Montag, 23. Februar 2009 20:32
To: cgmo-webcgm@lists.oasis-open.org
Subject: [cgmo-webcgm] temporal/spatial priority and Style Properties

Scenario:  A picture contains 3 APS:  A, B, C.  They occur in that order
in 
the metafile.  Suppose B partially overlaps and partially occludes A,
and C 
partially overlaps and partially occludes B.

Now suppose setStyleProperties changes the appearance of B,
necessitating a 
redraw of B.

Question:  The correct picture requires the redraw of all three APS
(i.e., 
the whole picture) in the proper order (A-B-C), correct?  (I.e., one
cannot 
simply redraw an affected target object, unless one has done some 
optimization calculations to ensure that nothing overlays the affected
object.)

I think the answer has to be "yes", otherwise one would start to get all

sorts of ugly picture damage while doing DOM visual enhancements on a 
picture.

Does anyone disagree?

(I'm just trying to be safe to not say something misleading in some new 
drafting that I'm doing.)

-Lofton.


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