Re: [Shotwell] Shotwell importing thumbnails from Nexus 7

[Jim Nelson <jim yorba org>]

On Thu, May 22, 2014 at 1:58 PM, Colin Law <clanlaw gmail com> wrote:

OK, I have tried that, but still no joy. It had not occurred to me that it is up to the tablet, I had assumed that Shotwell was iterating the folders looking for image files. I have set the tablet up to use MTP, Shotwell did not see it at all when I tried PTP.

Loading images and previews off of devices is a bizarre and opaque dance between Shotwell, gphoto2, and the device itself.

The USB device gets to choose what part of its filesystem it wants to expose via USB.  It doesn't have to expose any of it, or it can "fake" a filesystem that maps to some other internal structure.  The iPhone used to work like this, as I recall.

gphoto2 adds a layer of intelligence for multipurpose devices like phones and tablets.  For example, most Android phones expose their entire filesystem which gphoto2 used to dutifully expose to the application.  This meant Shotwell was finding images stored in the browser cache, which obviously isn't very useful.  gphoto2 attempts to find the root of the device's stored photos using a combination of device-detection and well-known paths.  I don't know all the details, but that's what I've picked up over the years.

Finally, since even that's not perfect, Shotwell also looks for well-known paths to iterate from.  Some high-end cameras store video metadata in special locations, and we need to do this as well for RAW+JPEG matching.

The variation you're seeing between your devices (and perhaps due to cyanogemod) is probably due to one or more factors above.

I don't know if it is relevant, but in the import preview in Shotwell it shows the thumbnails as a red circle and diagonal line on a grey background rather than the actual image.

That means Shotwell requested a preview for the image from the device and it didn't return one.  This is common with RAW photos as well as some devices where gphoto2 doesn't know where thumbnails are stored.  Shotwell doesn't generate previews from the device photos because that means downloading the entire image.

-- Jim