uploads: add support for uploading .avif files.

Features of AVIF include:

* Lossless and lossy compression.
* High dynamic range (HDR) images
* Wide color gamut images (i.e. 10- and 12-bit color depths)
* Transparency (through alpha planes).
* Animations (with an optional cover image).
* Auxiliary image sequences, where the file contains a single primary
  image and a short secondary video, like Apple's Live Photos.
* Metadata rotation, mirroring, and cropping.

The AVIF format is still relatively new and some of these features aren't well
supported by browsers or other software:

* Animated AVIFs aren't supported by Firefox or by libvips.
* HDR images aren't supported by Firefox.
* Rotated, mirrored, and cropped AVIFs aren't supported by Firefox or Chrome.
* Image grids, where the file contains multiple images that are tiled
  together into one big image, aren't supported by Firefox.
* AVIF as a whole has only been supported for a year or two by Chrome
  and Firefox, and less than a year by Safari.

For these reasons, only basic AVIFs that don't use animation, rotation,
cropping, or image grids can be uploaded.

test/files/avif/README.md

@@ -0,0 +1,7 @@
+Test file sources:
+
+* https://github.com/link-u/avif-sample-images
+* https://github.com/AOMediaCodec/av1-avif/tree/master/testFiles
+* https://github.com/AOMediaCodec/libavif/tree/main/tests/data
+* https://colinbendell.github.io/webperf/animated-gif-decode/avif.html
+* https://0xc0000054.github.io/pdn-avif/using-image-grids.html

test/functional/uploads_controller_test.rb

@@ -195,6 +195,33 @@ class UploadsControllerTest < ActionDispatch::IntegrationTest
         end
       end
 
+      context "for an unsupported AVIF file" do
+        should "fail for a grid image" do
+          create_upload!("test/files/avif/Image grid example.avif", user: @user)
+          assert_match("File type is not supported", Upload.last.error)
+        end
+
+        should "fail for a cropped image" do
+          create_upload!("test/files/avif/kimono.crop.avif", user: @user)
+          assert_match("File type is not supported", Upload.last.error)
+        end
+
+        should "fail for a rotated image" do
+          create_upload!("test/files/avif/kimono.rotate90.avif", user: @user)
+          assert_match("File type is not supported", Upload.last.error)
+        end
+
+        should "fail for an image sequence" do
+          create_upload!("test/files/avif/sequence-with-pitm.avif", user: @user)
+          assert_match("File type is not supported", Upload.last.error)
+        end
+
+        should "fail for a still image with an auxiliary image sequence" do
+          create_upload!("test/files/avif/sequence-with-pitm-avif-major.avif", user: @user)
+          assert_match("File type is not supported", Upload.last.error)
+        end
+      end
+
       context "for a video longer than the video length limit" do
         should "fail for a regular user" do
           create_upload!("https://cdn.donmai.us/original/63/cb/63cb09f2526ef3ac14f11c011516ad9b.webm", user: @user)
@@ -267,6 +294,12 @@ class UploadsControllerTest < ActionDispatch::IntegrationTest
         should_upload_successfully("test/files/test-512x512.webm")
         should_upload_successfully("test/files/test-audio.m4v")
         # should_upload_successfully("test/files/compressed.swf")
+
+        should_upload_successfully("test/files/avif/fox.profile0.8bpc.yuv420.monochrome.avif")
+        should_upload_successfully("test/files/avif/hdr_cosmos01000_cicp9-16-9_yuv420_limited_qp40.avif")
+        should_upload_successfully("test/files/avif/hdr_cosmos01000_cicp9-16-9_yuv444_full_qp40.avif")
+        should_upload_successfully("test/files/avif/paris_icc_exif_xmp.avif")
+        should_upload_successfully("test/files/avif/tiger_3layer_1res.avif")
       end
 
       context "uploading multiple files from your computer" do

test/unit/media_file_test.rb

@@ -21,6 +21,10 @@ class MediaFileTest < ActiveSupport::TestCase
       assert_equal([32, 32], MediaFile.open("test/files/test-static-32x32.gif").dimensions)
     end
 
+    should "determine the correct dimensions for an AVIF file" do
+      assert_equal([2048, 858], MediaFile.open("test/files/avif/hdr_cosmos01000_cicp9-16-9_yuv420_limited_qp40.avif").dimensions)
+    end
+
     should "determine the correct dimensions for a webm file" do
       skip unless MediaFile.videos_enabled?
       assert_equal([512, 512], MediaFile.open("test/files/test-512x512.webm").dimensions)
@@ -85,6 +89,12 @@ class MediaFileTest < ActiveSupport::TestCase
       assert_equal(:gif, MediaFile.open("test/files/test-static-32x32.gif").file_ext)
     end
 
+    should "determine the correct extension for an AVIF file" do
+      Dir["test/files/avif/*.avif"].each do |file|
+        assert_equal(:avif, MediaFile.open(file).file_ext)
+      end
+    end
+
     should "determine the correct extension for a webm file" do
       assert_equal(:webm, MediaFile.open("test/files/test-512x512.webm").file_ext)
     end
@@ -127,6 +137,7 @@ class MediaFileTest < ActiveSupport::TestCase
       assert_equal([150, 101], MediaFile.open("test/files/test.jpg").preview(150, 150).dimensions)
       assert_equal([113, 150], MediaFile.open("test/files/test.png").preview(150, 150).dimensions)
       assert_equal([150, 150], MediaFile.open("test/files/test.gif").preview(150, 150).dimensions)
+      assert_equal([150, 63], MediaFile.open("test/files/avif/hdr_cosmos01000_cicp9-16-9_yuv420_limited_qp40.avif").preview(150, 150).dimensions)
     end
 
     should "generate a preview image for an animated image" do
@@ -294,6 +305,72 @@ class MediaFileTest < ActiveSupport::TestCase
     end
   end
 
+  context "an AVIF file" do
+    should "be able to read AVIF files" do
+      Dir["test/files/avif/*.avif"].each do |file|
+        assert_nothing_raised { MediaFile.open(file).attributes }
+      end
+    end
+
+    should "detect supported files" do
+      assert_equal(true, MediaFile.open("test/files/avif/paris_icc_exif_xmp.avif").is_supported?)
+      assert_equal(true, MediaFile.open("test/files/avif/hdr_cosmos01000_cicp9-16-9_yuv420_limited_qp40.avif").is_supported?)
+      assert_equal(true, MediaFile.open("test/files/avif/hdr_cosmos01000_cicp9-16-9_yuv444_full_qp40.avif").is_supported?)
+      assert_equal(true, MediaFile.open("test/files/avif/fox.profile0.8bpc.yuv420.monochrome.avif").is_supported?)
+      assert_equal(true, MediaFile.open("test/files/avif/tiger_3layer_1res.avif").is_supported?)
+    end
+
+    should "detect unsupported files" do
+      assert_equal(false, MediaFile.open("test/files/avif/Image grid example.avif").is_supported?)
+      assert_equal(false, MediaFile.open("test/files/avif/kimono.crop.avif").is_supported?)
+      assert_equal(false, MediaFile.open("test/files/avif/kimono.rotate90.avif").is_supported?)
+      assert_equal(false, MediaFile.open("test/files/avif/sequence-with-pitm-avif-major.avif").is_supported?)
+      assert_equal(false, MediaFile.open("test/files/avif/sequence-with-pitm.avif").is_supported?)
+      assert_equal(false, MediaFile.open("test/files/avif/sequence-without-pitm.avif").is_supported?)
+      assert_equal(false, MediaFile.open("test/files/avif/star-8bpc.avif").is_supported?)
+
+      # XXX These should be unsupported, but aren't.
+      # assert_equal(false, MediaFile.open("test/files/avif/alpha_video.avif").is_supported?)
+      # assert_equal(false, MediaFile.open("test/files/avif/plum-blossom-small-profile0.8bpc.yuv420.alpha-full.avif").is_supported?)
+      # assert_equal(false, MediaFile.open("test/files/avif/kimono.mirror-horizontal.avif").is_supported?)
+    end
+
+    should "detect animated files" do
+      assert_equal(true, MediaFile.open("test/files/avif/sequence-with-pitm.avif").is_animated?)
+      assert_equal(true, MediaFile.open("test/files/avif/sequence-without-pitm.avif").is_animated?)
+      assert_equal(true, MediaFile.open("test/files/avif/alpha_video.avif").is_animated?)
+      assert_equal(true, MediaFile.open("test/files/avif/star-8bpc.avif").is_animated?)
+
+      assert_equal(48, MediaFile.open("test/files/avif/sequence-with-pitm.avif").frame_count)
+      assert_equal(95, MediaFile.open("test/files/avif/sequence-without-pitm.avif").frame_count)
+      assert_equal(48, MediaFile.open("test/files/avif/alpha_video.avif").frame_count)
+      assert_equal(5, MediaFile.open("test/files/avif/star-8bpc.avif").frame_count)
+    end
+
+    should "detect static images with an auxiliary image sequence" do
+      assert_equal(true, MediaFile.open("test/files/avif/sequence-with-pitm-avif-major.avif").metadata.is_animated_avif?)
+      assert_equal(false, MediaFile.open("test/files/avif/sequence-with-pitm-avif-major.avif").is_animated?)
+      assert_equal(1, MediaFile.open("test/files/avif/sequence-with-pitm-avif-major.avif").frame_count)
+    end
+
+    should "detect rotated images" do
+      assert_equal(true, MediaFile.open("test/files/avif/kimono.rotate90.avif").metadata.is_rotated?)
+    end
+
+    should "detect monochrome images" do
+      assert_equal(true, MediaFile.open("test/files/avif/fox.profile0.8bpc.yuv420.monochrome.avif").metadata.is_greyscale?)
+    end
+
+    should "be able to generate a preview" do
+      assert_equal([180, 75], MediaFile.open("test/files/avif/hdr_cosmos01000_cicp9-16-9_yuv420_limited_qp40.avif").preview(180, 180).dimensions)
+      assert_equal([180, 75], MediaFile.open("test/files/avif/hdr_cosmos01000_cicp9-16-9_yuv444_full_qp40.avif").preview(180, 180).dimensions)
+      assert_equal([180, 135], MediaFile.open("test/files/avif/paris_icc_exif_xmp.avif").preview(180, 180).dimensions)
+      assert_equal([180, 180], MediaFile.open("test/files/avif/Image grid example.avif").preview(180, 180).dimensions)
+      assert_equal([180, 120], MediaFile.open("test/files/avif/fox.profile0.8bpc.yuv420.monochrome.avif").preview(180, 180).dimensions)
+      assert_equal([180, 123], MediaFile.open("test/files/avif/tiger_3layer_1res.avif").preview(180, 180).dimensions)
+    end
+  end
+
   context "a corrupt GIF" do
     should "still read the metadata" do
       @file = MediaFile.open("test/files/test-corrupt.gif")

test/unit/post_test.rb

@@ -1217,12 +1217,19 @@ class PostTest < ActiveSupport::TestCase
       end
 
       context "a greyscale image missing the greyscale tag" do
-        should "automatically add the greyscale tag" do
+        should "automatically add the greyscale tag for a monochrome JPEG file" do
           @media_asset = MediaAsset.upload!("test/files/test-grey-no-profile.jpg")
           @post.update!(md5: @media_asset.md5)
           @post.reload.update!(tag_string: "tagme")
           assert_equal("greyscale tagme", @post.tag_string)
         end
+
+        should "automatically add the greyscale tag for a monochrome AVIF file" do
+          @media_asset = MediaAsset.upload!("test/files/avif/fox.profile0.8bpc.yuv420.monochrome.avif")
+          @post.update!(md5: @media_asset.md5)
+          @post.reload.update!(tag_string: "tagme")
+          assert_equal("greyscale tagme", @post.tag_string)
+        end
       end
 
       context "an exif-rotated image missing the exif_rotation tag" do