Re[2]: [cgmo-webcgm] Question: object onload param

[Benoit Bezaire <benoit@itedo.com>]

Hi Lofton,

As far as I can remember:

 - the initial intent was just to have an onload event (plain and
 simple).
 - then we realized that by the time a user added the onload event
 listener, the CGM was done loading (the event was dispatched too
 late). (this is happening because scripts are always executed on the
 outside).
 - so we opted for the 'onload' object param, which lets
 implementation more options on when to dispatch the event.
 - now it turns out that the spec is unclear, is the 'onload' event
 dispatch when IE is done parsing the 'object' tag or is it
 dispatched when a WebCGM illustration is loaded.
 - note 1: it is possible to parse the 'object' tag without loading a
 CGM file (ex: no 'data' attribute on the object tag)
 - note 2: 'onload' being dispatched after a CGM file is loaded
 _could_ imply that it is dispatched every time the 'src' attribute is
 changed. 

 I hope this recaps well the situation.
 
 I think the way forward is to nail down what is most useful for the
 users.

-- 
Regards,
 Benoit   mailto:benoit@itedo.com
 
Friday, December 9, 2005, 11:59:54 AM, you wrote:

> ALL --

> I need help finding documented history of this...

> At 02:14 PM 12/7/2005 -0500, Benoit Bezaire wrote:
>>[...]I haven't heard anything about anyone regarding the onload issue.
>>
>>Could we simply start by having everyone describe what they wish to
>>accomplish with the onload event (i.e., what do you want to do with
>>it)?

> I have started one step further back -- to see if I could find 
> *documentation* about why we added it (the onload <param> of <object>) in
> the first place.  I.e., there must have been something that we wanted to
> do, but couldn't do with addEventListener() on the Metafile interface, right?

> For reference, Benoit submitted the proposed text to the TC list on 
> 6/29/05.  I have done a little searching of the archives, and found one
> message thread that contains some hints:

> http://lists.oasis-open.org/archives/cgmo-webcgm/200503/msg00032.html

> ALL -- can anyone find either a mail archive ISSUE, or  telecon minutes,
> which documents the resolution to add the <param> onload element?

> Or can you remember clearly, why we thought we needed it, when we decided
> to add it, in the Mar-Jun timeframe?

> Regards,
> -Lofton.




>>Friday, November 25, 2005, 7:43:12 AM, you wrote:
>>
>> > Hi,
>>
>> >   The current WebCGM 2.0 specification says the following about the
>> >   'onload' param (of the Object tag):
>> >   - [...] allows script writers to manipulate the WebCGM DOM at the
>> >   point at which the user agent has fully parsed the object tag and
>> >   its descendants and is ready to render the object to the screen.
>>
>> >   Ralf and I interpreted this differently. One of us thought it meant
>> >   that the onload would be dispatch when the ActiveX is loaded, and
>> >   the other thought that it meant the onload is dispatched when the
>> >   Metafile is loaded? There is a difference. From a technical
>> >   perspective the ActiveX can be loaded without a CGM file (as long as
>> >   the MIME type is specified on the 'object' tag, the ActiveX will be
>> >   created).
>>
>> >   We noticed the problem when trying the WebCGMEvent test. The 'src'
>> >   attribute is actually set in the script that is called via the
>> >   onload param.
>>
>> >   So when should we dispatch the onload event?
>>
>> >   We see advantages to both interpretations:
>> >   i) When the ActiveX is loaded... allows to set the 'src' parameter
>> >   in the onload event handler or alternatively, possibly modify via
>> >   the DOM the CGM before the first display.
>>
>> >   ii) When the Metafile is loaded... is like a DOM Mutation event
>> >   where you get notified that the document has change. In this case
>> >   you would get the onload every time the 'src' attribute is set or
>> >   for each internal link to a new WebCGM file. The use case here is to
>> >   extract metadata information to be interpreted by the host
>> >   application following each load.
>>
>> >   What was the intent?
>> >   Which is needed?
>>
>> >   Regards,