[Thunar-dev] PDF Thumbnailer

[Erlend Davidson]

I want to include a simple PDF thumbnailer for thunar, which uses 
ImageMagick.  I know there is already one, but it depends on evince 
being installed which would require a number of gnome libraries - not 
everyone wants to do this, especially not for a simple thumbnail.

The trouble is if I include a thumbnailer which supports a format 
already supported by an existing thumbnailer - what happens?  I presume 
mine (being added to the system later) would override thunar's default, 
which probably isn't the intended option.  If you have evince installed 
then I would say it is the best (fastest) means of thumbnailing a PDF.

This this in mind I want to propose to Benedict that the .desktop files 
for each thumbnailer have another field:
X-Thumbnailer-Priority
which is a number: 1 being a low priority and anything above that 
increasingly higher priority.  The default priority for any thumbnailer 
in thunar should be 10, that way when I want to include (for example) 
the PDF thumbnailer I can set the priority to be 5... when 
/usr/libexec/thunar-vfs-update-thumbnailers-cache-1 is run by the user 
the highest priority thumbnailers which have their TryExec found will be 
added to the thumbnailer cache.

For example if evince is not installed and 
/usr/libexec/thunar-vfs-update-thumbnailers-cache-1 is run it,
1. looks at both thunar-thumbnailers' and thunar's (evince) .desktop files
2. sees that evince has a higher priority (because it is faster it 
should be given the higher priority)
3. sees that evince-thumbnailer is not on tha $PATH, so uses the 
thumbnailer with the next highest priority.

This seems like the simplest solution to me, as it only requires the 
thunar-vfs-update-thumbnailers-cache-1 command to be updated.

This also fixes a problem caused by ffmpeg-thumbnailer, which can 
override totem-thumbnailer.

Erlend