A Standard for Thumbnailers

[Erlend Davidson]

Carsten Haitzler (The Rasterman) wrote:
> On Tue, 09 Jan 2007 12:08:46 +0100 Benedikt Meurer <benny at xfce.org> babbled:
>
>   
>> Stanislav Brabec wrote:
>>     
>>> - Image files in public directories are thumbnailed many times:
>>>   once for each accessing user.
>>>       
>> Sharing thumbnails might be a security problem.
>>
>>     
>>> - Thumbnails on removable media are thumbnailed many times: once for
>>>   each machine, where medium is accessed
>>>       
>> IIRC the standard already covers this, tho it's not implemented in Xfce
>> and GNOME.
>>
>>     
>>> - Thumbnail files are often larger than images itself, especially for
>>>   jpeg images below 20kB in size.
>>>       
>> The software can detect this and load the JPEG directly.
>>
>>     
>>> - There is a very small chance to detect deleted images and delete
>>>   corresponding thumbnail.
>>>       
>> The file manager should clean up the thumbnails when deleting files.
>>
>>     
>>> Use unique inode_number/volume_id instead of file_path.
>>>       
>> This will not work with certain FUSE file systems, that generate unique
>> inodes on-demand, because it's likely that the inodes will be different
>> each time the file system is mounted.
>>
>>     
>>> Haw widely used desktop-neutral thumbnailing library understanding many
>>> embedded thumbnails and providing thumbnailing for images without
>>> embedded thumbnail.
>>>       
>> I think external thumbnailer as used by Thunar/Nautilus are better,
>> because it's more flexible and avoids loading various libraries required
>> to generate thumbnails for different formats into the processes.
>>
>> Using .desktop files to register thumbnailers instead of GConf should be
>> fine for desktop-neutral usage.
>>
>>     
>>> Allow jpeg thumbnails.
>>>       
>> Aside from maybe a few bytes saved per thumbnail, why would you want to
>> do this?
>>     
>
> it's nto a few bytes. for 128x128 sizes thumbs a thumbnail can go from a 20k
> png to a 2k jpeg very very very easily. the jpeg thumbs invariably are
> significantly smaller than the png ones (depending on the quality level you are
> happy with). over the space of a few thousand thumbnails this make a BIG
> difference.
>   
I have 6731 thumbnails in ~/thumbnails/normal.  This directory has a 
size of 110MB, so that's about 15KB a file.  My home directory has 25GB 
of used space, with all pictures, latex files, postscript files, pdf 
files (which I have a lot of) being thumbnailed, so that seems quite 
small to me.

Thumbnails are quite a high-end feature anyway - even on a fast computer 
they take a little time to produce.
>   
>>> Thumbnails can use file system extended attributes.
>>>       
>> Not every file system supports that. What would be stored in the
>> extended attributes anyway?
>>
>> Benedikt
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>>
>>     
>
>
>