Re: BonoboPreview initiative - png in a control

[Havoc Pennington <hp redhat com>]

Chris Phelps <chicane reninet com> writes: 
> Ok, so to refocus the topic here -> No thumbnailing will be done...that
> is complete crack and everyone ought to know it.

I don't really agree - saving a preview in image form would be more
robust and more efficient, IMO. Opening a component to render a
spreadsheet would mean essentially loading all of Gnumeric, which is
just going to be too slow and high-overhead for a file selector, and
also means that looking at a file means executing it, so you would
need Gnumeric in some sort of sandbox mode - it's all a big can of
worms.  Moreover you can't do it if you don't have Gnumeric installed
and are e.g. looking at a file someone sent you.

I don't think a preview mechanism is the same as thumbnailing; the
thumbnailing spec is just about how to cache previews to be displayed
in Nautilus or a file selector, i.e. it's a caching mechanism. The
preview mechanism is about how to generate the thumbnail in the first
place, and isn't covered in the thumbnailing spec.

Right now we have an "ad hoc" preview mechanism, which is that
Nautilus knows how to generate previews for many kinds of file
(images, text files, etc.). So it might be nice to have a way to get a
preview-generating component for different sorts of file. But I would
hope that most of those components would extract a pre-saved image
from the file. That is, say Gnumeric would make a preview image and
save that inside the XML file in some way. Then its preview component
would just open the XML file and yank out the relevant part and pass
it back as an image. The thumbnailing spec would then be used by
Nautilus, Konqueror, or file selector to cache that image.

The thumbnail caching allows us to have expensive preview components
when required, but it'd still be nice to make preview-generation as
cheap and robust as it possibly can be.

Anyway, I see no reason to have interactive previews, ergo previews
are just images, which can be cached using the thumbnail spec, and
previews may as well be displayed as images as well, and the
preview-generator components kept simple by returning images.

That will be fast, robust, easy to implement, and a perfectly good UI.

.02,
Havoc