[Thunar-dev] A Standard for Thumbnailers

[Erlend Davidson]

Benedikt Meurer wrote:
> Erlend Davidson wrote:
>   
>>> Checking my own source again... you should be able to store the
>>> thumbnail as JPEG. thunar_vfs_thumb_factory_generate_thumbnail() will
>>> also accept JPEGs and convert them to PNGs internally.
>>>       
>> Ok, I've tested this - it doesn't work.  Thinking about it this makes sense:
>> thunar invokes the raw-thumbnailer, saying "produce a thumbnail of ifile 
>> called ofile".  ofile is a png image, or at least an image with a png 
>> extension.  But if the thumbnailer gives a .png file in which the format 
>> is actually jpg/ppm then pixbuf will get confused. 
>>     
>
> GdkPixbuf does content sniffing, so it'll properly detect the JPEG/PNM
> content. Also note that the extension of the ofile is not .png.
>
>   
>> Also, the 
>> raw-thumbnailer script won't get the chance to resize the image - so 
>> it'll be on the order 3000x2000 pixels!
>>     
>
> Uhm, that's HUGE. Better scale that down in a separate process to avoid
> growing Thunar's heap.
And then we're back to the orignal problem - manipulation I do with 
'convert' is very slow.  The options are probably to:
1. write a version of dcraw that outputs small png thumbnails instead of 
huge jpeg ones
2. have a small program like thunar-vfs-pixbuf-thumbnailer-1 that can 
take input from stdin (as thunar-vfs-pixbuf-thumbnailer-1 is at least 
10x as fast as convert).


The latter would be more useful I think - a kind of faster drop-in 
replacement for convert that only does thumbnails, although am I correct 
in saying pipes (|) are relatively slow?