RE: [XaraXtreme-dev] Text margin support

["Phil Martin" <Phil@xxxxxxxx>]

FYI:

XAR files don't have a "file format version" because that's not a useful
concept when different parts of the format can change at any time and
the rest of the file is loadable by older versions. (We learnt that from
ArtWorks.)

The versioning is done at record level and is entirely based on the
record TAG numbers themselves. Any format changes require a new record
TAG so that older loaders can't be confused by changes in records they
think they understand.

If you add a new compound tag then you should mark it as "Atomic" so
that older loaders will skip that entire subtree.

If you add a new tag that's critical to the correct loading/rendering of
the file you can mark it as "Essential" so that older loaders will abort
if they encounter it.

Phil 

> -----Original Message-----
> From: owner-dev@xxxxxxxxxxxxxxxx 
> [mailto:owner-dev@xxxxxxxxxxxxxxxx] On Behalf Of Martin Wuerthner
> Sent: 19 July 2006 12:40
> To: dev@xxxxxxxxxxxxxx
> Subject: Re: [XaraXtreme-dev] Text margin support
> 
> In message <44BE0495.9030709@xxxxxxxxxxx>
>           Alex Bligh <alex@xxxxxxxxxxx> wrote:
> 
> > Could you fill me in on how the new text margins etc.
> > are saved? Specifically:
> > 
> > * Are they currently saved & loaded?
> 
> Yes.
> 
> > * Is there a file format change?
> 
> If you mean that are there new records in the file, then yes, 
> of course. There are 5 new records:
> - tab node
> - tab ruler attribute
> - left margin attribute
> - first indent attribute
> - right margin attribute
> 
> There has not been a formal file format version change, but 
> it might be a good idea to do that when saving a file with 
> any of the new attributes (remember that default attributes 
> are not saved, so files not using any of the new features 
> will not have any of the new attributes in them). The 
> question is whether we want to prevent previous versions from 
> loading the file altogether.
> 
> > * If so, what happens if you try and load files
> >    with new-style text objects into release Xtreme?
> 
> I have not tried with release Xtreme but XaraLX release 0.6 
> displays a message stating that non-essential data has been 
> ignored. It then reads the file OK, but not surprisingly, all 
> tab characters and the tab ruler/margin attributes have vanished.
> 
> Martin
>