Fix a bug where generating thumbnails failed for certain images when
using libvips 8.10. Specifically, it failed for single-channel greyscale
images and four-channel CMYK images without an embedded color profile.
In these cases we specified an sRGB fallback profile, but under libvips
8.10 this failed because the sRGB profile was incompatible with
single-channel and four-channel images. Before libvips 8.10 this worked,
but as of 8.10 it's a hard error.
The way libvips handles fallback color profiles differs across versions,
so we have to use different arguments for different versions. In 8.7,
vips doesn't have builtin color profiles, so we have to specify our own
manually. In 8.9, it has builtin profiles, so we can omit the import
profile, but we're still required to set the export profile to sRGB,
otherwise it will leave CMYK images as CMYK when generating thumbnails.
In 8.10, we have to _not_ to set the import or export profile to sRGB,
otherwise it will fail with an incompatible profile error when it tries
to convert CMYK images to RGB.
The builtin sRGB profile used by libvips[1] is different than the one we
used previously[2]. The builtin one comes from LCMS[3], whereas ours
came from ArgyllCMS.[4] Not all sRGB profiles are created the same[5],
so this may result in some imperceptible differences in thumbnail
output. The ArgyllCMS profile was used before because it seemed to be
the best one[6], but realistically it probably doesn't matter.
1: https://github.com/libvips/libvips/blob/v8.10.6/libvips/colour/profiles/sRGB.icm
2: 906eec190d/config/sRGB.icm
3: https://www.littlecms.com/
4: https://www.argyllcms.com/
5: https://ninedegreesbelow.com/photography/srgb-profile-comparison.html
6: https://ninedegreesbelow.com/photography/srgb-profile-comparison.html#addendum
Fix regression in ef2857667 that caused animated GIFs and PNGs to
generate thumbnails that were larger than 150x150.
Also fix a bug with cropped previews not being generated for animated
GIFs and PNGs.
* Move image thumbnail generation code to MediaFile::Image.
* Move video thumbnail generation code to MediaFile::Video.
* Move ugoira->webm conversion code to MediaFile::Ugoira.
This separates thumbnail generation from the upload process so that it's
possible to generate thumbnails outside of uploads.
* Fix corrupted image detection. We were shelling out to vips and trying
to grep for error messages, but the error message for jpeg files changed.
Now we load the file in ruby vips, which raises an error on failure.
* Don't attempt to redownload corrupted images. If a download completes
without any errors yet the downloaded file is corrupt, then something is
wrong at the source and redownloading is unlikely to help. Let the
upload fail and the user retry if necessary.
* Validate that all uploads are uncorrupted, including files uploaded
from a computer, not just files uploaded from a source.
