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Viewer Behavior. A 'grobject' APS may be selected
by the user ("pick"). The viewer shall decide about the pick selection in the
following manner:
- If the object does not contain a 'region' attribute and contains no a
LinkURI attributes no further action is required.
- If the object contains at least one 'LinkURI' attribute but no
'region' attribute, a click on non-transparent areas of the graphical
elements of the object selects the object. If the object does not contain
any graphical primitives no further action is required. If the object
contains more than one LinkURI attribute, the user shall be given a choice
of which URI to navigate.
- If the object contains a 'region' attribute and contains at
least one LinkURI attribute, then the 'region' shall be used for
selection. If the object contains more than one LinkURI attribute, the
user shall be given a choice of which URI to navigate.
- If the object contains a 'region' attribute but no LinkURI
attributes no further action is required.
It is possible that a user selection ("pick") of a
object in a displayed WebCGM picture may not have a single unambiguous result
- the cursor location may reside within the geometric extent or 'region' of
more than one APS. In such a case, the pick priority is as follows:
- If the pick has selected only one APS (and it contains a linkURI), then
it is the one which is picked;
- If the pick has selected more than one APS (and each contains
a linkURI), and the APSs are not nested, then the APS with the highest
pick priority is the one whose picking region occurs latest in the picture
(see the 'region' APS Attribute for definition of "picking region").
- If the pick has selected more than one APS (and each contains
a linkURI), and the APSs are nested, the user shall be given a choice of
which URI to navigate.
Viewers shall give
visual feedback to the user that a successful pick has occurred, and an
indication of the particular object (or region) which has been picked. The
exact method of feedback is viewer dependent.