- From: Lofton Henderson <lofton@rockynet.com>
- Date: Thu, 04 Dec 2008 10:19:01 -0700
- To: "WebCGM WG" <public-webcgm-wg@w3.org>
- Message-Id: <5.1.0.14.2.20081204101539.03c1a450@localhost>
All -- This is a dangling open piece of Benoit's setView() questions. We closed the other piece (about different aspect ratios). I can't find any thread discussion about this piece, after Benoit's message below (top), and it apparently remains open. Discussion? -Lofton. At 09:44 AM 11/19/2008 -0500, Bezaire, Benoit wrote: >I remember this thread. I don't want to reopen old issues. > >However, for this particular API, a script writer can easily loose the >display (zooming on a very small rectangle or zooming our far enough that >nothing is displayed). I think the API should at least return a more >meaningful value. > >Some options: >i) boolean: TRUE if new view was set; FALSE is rectangle was invalid. >ii) float: returns the scale factor between the old view and the new >view. > 0 is successful, failed otherwise. >iii) WebCGMRect: a rectangle defining the old view. > >Any of those would help the script writer understand what went wrong, >instead of getting in touch with technical support. > >Benoit. > > >---------- >From: Lofton Henderson [mailto:lofton@rockynet.com] >Sent: Tuesday, November 18, 2008 7:08 PM >To: Bezaire, Benoit; WebCGM WG >Subject: Re: Question about setView() > >At 08:57 AM 11/18/2008 -0500, Bezaire, Benoit wrote: >>I'm wondering if the wording of setView() is not a bit short? The draft >>doesn't say anything about invalid rectangles being passed in for example. >> >>Should more feedback be sent to the user? Currently, the function >>prototype has a void return type. Should we change that to a boolean or >>something else? or throw an exception perhaps. > >Dieter raised and we discussed a similar question a few months back. As a >general rule, CGM and WebCGM say what happens with valid input but have >been relatively silent about error fallbacks, viewer error reactions, >etc. What we have done most recently is say something like "...has no >effect". We generally have not gone to more extensive error >reactions. See for example the 'grnode' stuff that we added to the interfaces. > >My view is that, if we start opening the door to saying what viewers do >for this and that bad input, where do we stop? Should we go back and >define mandatory error responses for all bad input? > >Note that the profile (Ch.6) *does* talk a lot about "degeneracies". It >says what is the graphical effect of a degenerate primitive, etc., and >this is what is *suggested* in CGM:1999 itself -- WebCGM just makes it >normative. (But says nothing more about what the viewer should do when >encountering degeneracies. Silent? Warning? Task-bar "abnormality" icon?) > >I guess I favor "...invalid input has no effect, neither graphical nor to >the DOM tree." Then leave it to the implementor, what else the viewer >might do in the way of error response to the user. > >> >>I also question the possibility of a major scale change, ex: scaling in >>by a factor of 100 (and loosing sight of the overall picture). Should the >>user be told that such a change occurred? > >I guess I view this as another choice for implementors. > >I could also live with putting some valid limits on it. "Valid rectangles >shall not change the scale by more than ...blah..." > >-Lofton.
Received on Thursday, 4 December 2008 18:26:56 UTC