Add webp as a new framework default image type

Follows rails#38918 and
rails#38988

At the time, webp browser support was limited. Now 96% of browsers
support webp: https://caniuse.com/?search=webp

activestorage/CHANGELOG.md

@@ -1,3 +1,8 @@
+*   Add `image/webp` to `config.active_storage.web_image_content_types` when `load_defaults "7.2"`
+    is set.
+
+    *Lewis Buckley*
+
 *   Fix N+1 query when fetching preview images for non-image assets
 
     *Aaron Patterson & Justin Searls*

activestorage/test/models/variant_test.rb

@@ -114,6 +114,17 @@ class ActiveStorage::VariantTest < ActiveSupport::TestCase
     assert_equal 8, image.height
   end
 
+  test "resized variation of WEBP blob" do
+    blob = create_file_blob(filename: "valley.webp")
+    variant = blob.variant(resize_to_limit: [50, 50]).processed
+    assert_match(/valley\.webp/, variant.url)
+
+    image = read_image(variant)
+    assert_equal "WEBP", image.type
+    assert_equal 50, image.width
+    assert_equal 33, image.height
+  end
+
   test "optimized variation of GIF blob" do
     blob = create_file_blob(filename: "image.gif", content_type: "image/gif")
 

guides/source/configuring.md

@@ -58,6 +58,10 @@ NOTE: If you need to apply configuration directly to a class, use a [lazy load h
 
 Below are the default values associated with each target version. In cases of conflicting values, newer versions take precedence over older versions.
 
+#### Default Values for Target Version 7.2
+
+- [`config.active_storage.web_image_content_types`](#config-active-storage-web-image-content-types): `%w[image/png image/jpeg image/gif image/webp]`
+
 #### Default Values for Target Version 7.1
 
 - [`config.action_dispatch.debug_exception_log_level`](#config-action-dispatch-debug-exception-log-level): `:error`
@@ -2847,13 +2851,14 @@ config.active_storage.variable_content_types = %w(image/png image/gif image/jpeg
 
 Accepts an array of strings regarded as web image content types in which
 variants can be processed without being converted to the fallback PNG format.
-If you want to use `WebP` or `AVIF` variants in your application you can add
-`image/webp` or `image/avif` to this array.
-By default, this is defined as:
+For example, if you want to use `AVIF` variants in your application you can add
+`image/avif` to this array.
 
-```ruby
-config.active_storage.web_image_content_types = %w(image/png image/jpeg image/gif)
-```
+The default value depends on the `config.load_defaults` target version:
+| Starting with version | The default value is                            |
+| --------------------- | ----------------------------------------------- |
+| (original)            | `%w(image/png image/jpeg image/gif)`            |
+| 7.2                   | `%w(image/png image/jpeg image/gif image/webp)` |
 
 #### `config.active_storage.content_types_to_serve_as_binary`
 

railties/lib/rails/application/configuration.rb

@@ -323,6 +323,10 @@ def load_defaults(target_version)
           end
         when "7.2"
           load_defaults "7.1"
+
+          if respond_to?(:active_storage)
+            active_storage.web_image_content_types = %w( image/png image/jpeg image/gif image/webp )
+          end
         else
           raise "Unknown version #{target_version.to_s.inspect}"
         end

railties/lib/rails/generators/rails/app/templates/config/initializers/new_framework_defaults_7_2.rb.tt

@@ -8,3 +8,9 @@
 #
 # Read the Guide for Upgrading Ruby on Rails for more info on each option.
 # https://guides.rubyonrails.org/upgrading_ruby_on_rails.html
+
+# Adds webp to the list of content types Active Storage considers as an image
+# Prevents automatic conversion to a fallback PNG, and assumes clients support webp, as they support gif, jpeg, and png.
+# This is possible due to broad browser support for webp, but older browsers and email clients may still not support
+# webp.
+# Rails.application.config.active_storage.web_image_content_types = %w[image/png image/jpeg image/gif image/webp]