Re: Proposed new API for libgnomeui

[Alexander Larsson <alexl redhat com>]

On Tue, 17 Sep 2002, Dave Malcolm wrote:

> On Tuesday 17 September 2002 16:48, Alexander Larsson wrote:
> 
> <snip>
> 
> >
> > As a bonus I've added pluggable thumbnailing scripts.
> > By putting this:
> > video/x-msvideo: /home/alex/bin/avithumbnailer %i %o
> > application/pdf,application/postscript: gs  -sDEVICE=png16m -r11
> > -dFirstPage=1 -dLastPage=1 -sOutputFile=%o -dBATCH -dNOPAUSE %i
> >
> > in ~/.gnome2/thumbnailrc i was able to get this:
> > http://people.redhat.com/alexl/files/thumbnails2.png
> >
> 
> <snip>
> 
> Excellent - a few thoughts:
> (i) For the pdf/postcript files, you might want to add "-dSAFER" for 
> paranoia's sake; also -sDEVICE=png256 was a lot faster for me when I was 
> playing around with this, with no appreciable loss of quality (on my test 
> cases, at any rate)

Good stuff.
 
> (ii) Is ~/.gnome2/thumbnailrc just a temporary staging area?  We'd want to be 
> able to install new thumbnail generators on a per-mimetype and possibly 
> per-user basis.

I'm wary about automatically installing these things. They can take a lot 
of time to run and be potential security hazards. I don't think make 
install of some random package should suddenly make me vulnerable to some 
postscript attack. 

I'm willing to discuss the exact behaviour though, but let's first see if 
we can get the API in.
 
> (iii)  I've got a heavily hacked version of libole2 for extracting thumbnails 
> out of MS Office docs.   Where should I be sending patches etc?

No patches necessary. Just add stuff to your ~/.gnome2/thumbnailrc or 
/etc/gnome/thumbnailrc.

> <bluesky-mode>
> (iv) ultimately it might be better to implement thumbnailing as a component 
> rather than script-based system; you ask an activation framework to give you 
> a reference to an object that can thumbnail a particular mime-type.  That way 
> you can amortise startup costs when e.g. generating 10 thumbnails involving 
> something complex e.g. StarOffice, and hopefully avoid them altogether if 
> StarOffice's already been launched (you can hopefully ask it to generate some 
> thumbnails for you, without having to launch it yourself).   Though I'm not 
> familiar enought with Bonobo to implement this myself :-(

I'm not sure this is a good idea. If done in-process it brings in lots of 
libraries that could collide, and may introduce instabilities. Done 
as an out of process component is possible, but it feels quite 
overengineered to me.
 
> (v)  taking things further, this could be generalised to per-mimetype 
> metadata providers:   the component we've launched might be able to tell us 
> the page count of a document, the author, the dimensions in pixels etc.  
> (These could then be displayed in Nautilus - page count is probably more 
> interesting to users like my mother than size in bytes).  Recent versions of 
> the WIn32 Shell Namespace and Explorer collaborate to provide this kind of 
> functionality.
> </bluesky-mode>

I will hopefully soon have some time to work on pluggable property pages 
in Nautilus. These could be per-mimetype and have custom information or 
even editing of the file. They can also be per-filesystem and do stuff 
like ACLs.

-- 
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 Alexander Larsson                                            Red Hat, Inc 
                   alexl redhat com    alla lysator liu se 
He's a suave gay master criminal searching for his wife's true killer. She's a 
warm-hearted mutant socialite with the power to see death. They fight crime!