Thumbnails

[pcercuei]

It should be possible to support thumbnails by implementing the "Representative Sample" object properties.

The thumbnailing process itself should be deferred to an external program, pointed to in the config.

[jfdelnero]

@pcercuei which way should we use to pass the thumbnail image data to the uMTP daemon ?

[pcercuei]

@jfdelnero there is a Freedesktop standard for that; The directory /usr/share/thumbnailers contains *.thumbnailer files with the following schema (example):

[Thumbnailer Entry]
TryExec=/usr/bin/gdk-pixbuf-thumbnailer
Exec=/usr/bin/gdk-pixbuf-thumbnailer -s %s %u %o
MimeType=image/svg+xml;image/svg+xml-compressed;

The Exec= line tells you how the thumbnailer should be called, (%s: size; %u: url/filepath; %o: output file). It will write the thumbnail to the given output PNG file.

However I believe it's not umtprd's job to create the thumbnails (there is probably an existing daemon for that). Umtprd should only have to open the thumbnails from ~/.cache/thumbnails/normal/{md5 of file}.png, and if it exist, use this PNG as the thumbnail for the MTP object.