Dear Maintainer,

I was not getting thumbnails for heic/heif files.

I would expect that installing the heif-gdk-pixbuf should
be enough to enable support, but it needed editing the file
/usr/share/thumbnailers/gdk-pixbuf-thumbnailer.thumbnailer,
and adding the image/heif Mimetype.

Naturally this change will be lost everytime this package
will be upgraded.

I'd like a clean solution for this issue.

Norbert

Control: reassign -1 heif-gdk-pixbuf 1.10.0-2
Control: retitle -1 heif-gdk-pixbuf: should have Recommends on heif-thumbnailer?

I don't think this is really something that the gdk-pixbuf package can or
should solve on its own. The thumbnailer files in /usr/share/thumbnailers
are static, not dynamic, and gdk-pixbuf-thumbnailer.thumbnailer is
only designed to describe the formats that are supported by the base
gdk-pixbuf library.

One way it can be solved in packages that extend gdk-pixbuf would be for
them to have a Suggests, Recommends or Depends on libgdk-pixbuf2.0-bin, and
install a /usr/share/thumbnailers/foo-gdk-pixbuf.thumbnailer
that runs the same gdk-pixbuf-thumbnailer command, but has MimeType set
according to the MIME types for which this package adds support.
That's a direct equivalent of what happens in the librsvg2-common package,
also from GNOME, to add SVG support to gdk-pixbuf, which suggests that it
is the upstream-supported approach to getting more MIME types thumbnailed
via gdk-pixbuf.

However, in the particular case of libheif it seems that this is
unnecessary, because there is also a heif-thumbnailer package that
provides its own, more specific thumbnailing code (extracting a thumbnail
from metadata if available, rather than loading the entire HEIF image just
to scale it down). I would recommend installing that if you are interested
in HEIF files.

Authors of gdk-pixbuf plugins and .thumbnailer files should be aware that
file managers like Nautilus will trigger thumbnailing for downloaded files
(for example in ~/Downloads), and some web browsers will download files
into ~/Downloads without prompting under some circumstances (a "drive-by
download"). Combining these two factors means that a thumbnailer adds
significant attack surface to the system, so authors of gdk-pixbuf plugins
should not provide a corresponding .thumbnailer file for formats whose
decoder is not written defensively, with maliciously-crafted image files
in mind. Nautilus and libgnome-desktop attempt to mitigate any exploitable
bugs in thumbnailers by running them in a restricted sandbox environment,
but I don't think all consumers of the .thumbnailer mechanism do this.

As a result, even if it was straightforward to implement, I think it would
be inappropriate for gdk-pixbuf to automatically provide thumbnailing
services for unknown gdk-pixbuf plugins: the authors of plugins that
are believed to be robust against maliciously-crafted image files need to
take action to opt-in to participating in the thumbnailing mechanism, and
take responsibility for the consequences.

libheif maintainers: if heif-thumbnailer is considered safe for use,
then I think heif-gdk-pixbuf should probably have a Recommends (or
even Depends?) on heif-thumbnailer, to meet user expectations around
thumbnailing. If it's a Depends, then heif-thumbnailer should probably
become Multi-Arch: foreign, so that it does not prevent heif-gdk-pixbuf
from being Multi-Arch: same.

    smcv

Am Mo., 1. Feb. 2021 um 10:37 Uhr schrieb Simon McVittie <smcv@debian.org>:

Ok, thanks for the Explanation.

Should I open an issue for that package, or on some gnome package?
heif/heic is getting common, would be nice to have support "out of the box"

Norbert

No need, I've reassigned your bug report to heif-gdk-pixbuf already.

Today is the first time I've heard of this image format, so I don't think
it's necessarily key functionality for a desktop environment right now.
However, if you disagree, the place to request this would be a separate
wishlist bug report against one of the desktop metapackages (such as
"gnome").

Thanks,
    smcv

Am Mo., 1. Feb. 2021 um 11:27 Uhr schrieb Simon McVittie <smcv@debian.org>:

Getting pics in this format from my sons kindergarden.
Several Apple and Samsung phones (and I think cameras) use it by default
since a couple years. I am more concerned about the state of support in the
Linux world ;)

Yeah, I am considering doing that.

Thanks for helping,
Norbert.