ISSUE: Object behaviors

[Dieter Weidenbruck <dieter@itedo.com>]

All,

I had the action item to revise the object behaviors after the last telecon
to investigate the best way to incorporate all desired behaviors.

1. WebCGM 1.0 behaviors
The existing behaviors are
	highlight
	highlight_all
	view_context

We decided to deprecate view_context in favor of the new navigation
behaviors.


2. Proposed WebCGM 2.0 behaviors
For WebCGM 2.0, the object behaviors shall be extended to allow for detailed
control regarding navigation and highlighting.

	Navigation variants:
	full			- establish a full (shrink-to-fit) view of the entire picture
	move			- move object(s) into view, reduce scale if objects are bigger than
				  viewer's rectangle
	zoom			- zoom to object(s), fit destination rectangle into viewer's
rectangle


	Highlighting variants:
	highlight		- highlight specified object(s), remove highlighting on other
objects
				  (backward compatible with 1.0)
	highlightadd	- highlight specified object(s), don't remove existing
highlighting on
				  other objects

	All variant:
	all			- apply to all objects with this name.

In addition, there are combinations possible of these atomic behaviors.
After looking
at these combinations in detail, I want to propose a combination of these
atomic
expressions (following Lofton's idea) rather than spelling out a long list
of explicit
keywords.

3. New Proposal
This is my proposal, it comes in two variants:

Variant A:
objBehavior ::= navTerm ("_" highlightTerm)? ("_all")? |
		    highlightTerm ("_all")?
navTerm ::= full | zoom | move
hightlightTerm ::= highlight | highlightadd


Build the actual objectBehavior from a navigation term, a highlighting term,
and the
"all" keyword as desired.
Note that in this variant "highlight" and "highlight_all" could be build
preserving
full backward compatibility.

Variant B:
objBehavior ::= navTerm ("_" highlightTerm)? |
		    highlightTerm
navTerm ::= full | zoom | move
hightlightTerm ::= highlight | highlightadd


Build the actual objectBehavior from a navigation term and a highlighting
term as desired.
This variant doesn't use the keyword "all" anymore.

"All" only makes a difference if the object is specified by name. In WebCGM
1.0, we
had the following:
#name(myName,highlight)		highlight the first object with this name
#name(myName,highlight_all)	highlight all objects with this name

To highlight the first object with this name created a random effect based
on the
Z order in the file, no good control over this behavior. The most commonly
used
variant was "highlight_all". I believe it is safe to assume that if one
addresses
objects by name, that "all" is the desired behavior in all cases.
Hence, we can omit the "all" keyword and assume the associated behavior for
all
cases where addressing by name is used.
Note: This creates a minor issue regarding the definition of "highlight" and
"highlight_all" in WebCGM 1.0, however, I don't believe that we will break
applications by combining highlight and highlight_all into one behavior.


RECOMMENDATION: Variant B.

Regards,
Dieter