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posts: add 720x720 thumbnail size.

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This is used to provide higher resolution thumbnails for high pixel
density displays, such as phones or laptops. If your screen has a 2x
pixel density ratio, then 360x360 thumbnails will be rendered at 720x720
resolution.

We use WebP here because it's about 15% smaller than the equivalent
JPEG, and because if a device has a high enough pixel density to use
this, then it probably supports WebP.

720x720 thumbnails average about 36kb in size, compared to 20.35kb for
360x360 thumbnails and 7.55kb for 180x180 thumbnails.
This commit is contained in:
evazion
2021-12-05 08:23:49 -06:00
parent 92906f7d39
commit 9cb70fa632
4 changed files with 32 additions and 21 deletions
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12
app/logical/media_file/image.rb
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@@ -44,7 +44,7 @@ class MediaFile::Image < MediaFile
image.interpretation
end
def resize(max_width, max_height, format: :jpeg, **options)
def resize(max_width, max_height, format: :jpeg, quality: 85, **options)
# @see https://www.libvips.org/API/current/Using-vipsthumbnail.md.html
# @see https://www.libvips.org/API/current/libvips-resample.html#vips-thumbnail
if colorspace == :srgb
@@ -63,17 +63,21 @@ class MediaFile::Image < MediaFile
raise NotImplementedError
end
if resized_image.has_alpha?
resized_image = resized_image.flatten(background: 255)
end
output_file = Tempfile.new(["image-preview-#{md5}", ".#{format.to_s}"])
case format.to_sym
when :jpeg
# https://www.libvips.org/API/current/VipsForeignSave.html#vips-jpegsave
resized_image.jpegsave(output_file.path, Q: 85, background: 255, strip: true, interlace: true, optimize_coding: true, optimize_scans: true, trellis_quant: true, overshoot_deringing: true, quant_table: 3)
resized_image.jpegsave(output_file.path, Q: quality, strip: true, interlace: true, optimize_coding: true, optimize_scans: true, trellis_quant: true, overshoot_deringing: true, quant_table: 3)
when :webp
# https://www.libvips.org/API/current/VipsForeignSave.html#vips-webpsave
resized_image.webpsave(output_file.path, Q: 85, preset: :drawing, effort: 4, strip: true)
resized_image.webpsave(output_file.path, Q: quality, preset: :drawing, smart_subsample: false, effort: 4, strip: true)
when :avif
# https://www.libvips.org/API/current/VipsForeignSave.html#vips-heifsave
resized_image.heifsave(output_file.path, Q: 40, compression: :av1, effort: 4, strip: true)
resized_image.heifsave(output_file.path, Q: quality, compression: :av1, effort: 4, strip: true)
else
raise NotImplementedError
end