Re: [Gnome-print] Universal binary file format
- From: Damien Diederen <dash linuxbe org>
- To: Lauris Kaplinski <lauris ariman ee>
- Cc: gnome-print helixcode com
- Subject: Re: [Gnome-print] Universal binary file format
- Date: Wed, 19 Apr 2000 12:09:56 +0200
On Wed, Apr 19, 2000 at 11:10:04AM +0200, Lauris Kaplinski wrote:
> On 19 Apr 2000, Miguel de Icaza wrote:
> > > Then we'll start having compatibility problems - what if a program creates
> > > gnome-print-metafile-1.2, but renderer can handle only 1.1? Current format
> > > does not allow it to skip unknown commands, so it has simply give up -
> > > thing I hate with most commercial programs/file formats - they refuse to
> > > open file which contains only one bit information they cannot handle.
> > Lauris, but this will happen with many many things more.
Could you elaborate on this one, please ? I don't quite understand.
> > Ie, consider that one such command is "rotate 90 degrees", the output
> > will be completely messed.
> I hope that basic display capabilities will soon be good enough, that we
> does not need to change anything in foreseeable future. And while
> introducing new capabilities, it is usually possible to have nice backdrop
> capability. That problem with current file format is, that ANY new command
> will break completely the ability of older app/lib to render it.
> Just imagine something like:
> Command: set_hint
> Value: "Use envelope feeder for this page"
> It will break DISPLAY compatibility :(
Perhaps we should go the PNG way :
Size: XXX bytes
Value: Use envelope feeder
Size: XXX bytes
Value: 90° CCW
We can either encode the "Type" header in a bitfield, or use a fun hack like
the PNG people to name the chunks in mixed-case.
I think we should design *all* of our file formats such as it would be
possible for Gnumeric 2.0 to open Gnumeric 3.0 files, while dropping
unknown "features" if they are optional/recommanded but not mandatory.
Of course, unknown mandatory features could cause the loading to fail,
but that's life (and most new features in Word 97 vs Word 95 are certainly
* Pétition contre les brevets logiciels : http://lln.udev.org/sign.php3
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