Specifying thumbnailers as a service
l.lunak at suse.cz
Mon Sep 1 01:25:36 PDT 2008
On Friday 29 of August 2008, Philip Van Hoof wrote:
> Hi there,
> Not only filemanagers want to request the creation of a thumbnail. For
> example desktop search engines like Strigi and Tracker want to schedule
> the creation of thumbnails for certain of the contents that they find,
> ahead of time (not sure about Strigi, as one of Tracker's developers
> myself I'm sure about Tracker).
> This is why we would like to have a desktop wide DBus API for requesting
> the creation of a thumbnail. Not just a specification about how to store
> the thumbnails and where you can find them , but also a method to
> request thumbnails.
> We want to reuse the infrastructure that is available.
> We want to request the creation of a thumbnail for rather a lot of items
> so this API would have to accept a an array of paths to thumbnail-able
> items. When finished it would return an array of paths to the
Is this API also intended to be used by filemanagers? It appears to have
several performance problems for use in those:
- there is no notification about progress (i.e. when a thumbnail is done), so
a filemanager showing a directory would have to wait for all thumbnails
created there (unless it wants to watch the thumbnail directories for a
change). Also, even if there was such a signal, it would probably be nice to
also have a request for cancelling the create request, in order to change
what should be generated when the user scrolls around in a view with many
- not in your original proposal, but in the thread it is said that the create
request should not request a specific size, instead the thumbnailer should
handle sizes normally according to the thumbnailing spec. This would make the
generation take longer and presumably waste space with unused sizes.
- thumbnail generators usually don't go via saving to disk but use some more
efficient way (e.g. pass data in-process)
- also, it is not really necessary to actually keep thumbnails on the disk, I
use my image browser with the disk cache turned off, as that's generally
faster that way. The API however cannot work this way.
Since all applications using this API need to be handle the thumbnail spec
anyway, wouldn't it be better to have the API like
image create_thumbnail( string file, int size )
? Plus some simple way how to find which .so to load for this entry hook?
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