Fix #3582: Switch from ImageMagick to libvips

app/logical/danbooru_image_resizer.rb

@@ -1,52 +1,18 @@
 module DanbooruImageResizer
-  def resize(file, width, height, resize_quality = 90)
-    image = Magick::Image.read(file.path).first
-    geometry = "#{width}x>"
+  # Taken from ArgyllCMS 2.0.0 (see also: https://ninedegreesbelow.com/photography/srgb-profile-comparison.html)
+  SRGB_PROFILE = "#{Rails.root}/config/sRGB.icm"
+  # http://jcupitt.github.io/libvips/API/current/libvips-resample.html#vips-thumbnail
+  THUMBNAIL_OPTIONS = { size: :down, linear: false, auto_rotate: false, export_profile: SRGB_PROFILE }
+  # http://jcupitt.github.io/libvips/API/current/VipsForeignSave.html#vips-jpegsave
+  JPEG_OPTIONS = { background: 255, strip: true, interlace: true, optimize_coding: true }
 
-    if width == Danbooru.config.small_image_width
-      # wider than it is tall
-      geometry = "#{Danbooru.config.small_image_width}x#{Danbooru.config.small_image_width}>"
-    end
+  # https://github.com/jcupitt/libvips/wiki/HOWTO----Image-shrinking
+  # http://jcupitt.github.io/libvips/API/current/Using-vipsthumbnail.md.html
+  def self.resize(file, width, height, resize_quality = 90)
+    output_file = Tempfile.new
+    resized_image = Vips::Image.thumbnail(file.path, width, height: height, **THUMBNAIL_OPTIONS)
+    resized_image.jpegsave(output_file.path, Q: resize_quality, **JPEG_OPTIONS)
 
-    image.change_geometry(geometry) do |new_width, new_height, img|
-      img.resize!(new_width, new_height)
-      width = new_width
-      height = new_height
-    end
-
-    image = flatten(image, width, height)
-    image.strip!
-
-    output_file = Tempfile.new(binmode: true)
-    image.write("jpeg:" + output_file.path) do
-      self.quality = resize_quality
-      # setting PlaneInterlace enables progressive encoding for JPEGs
-      self.interlace = Magick::PlaneInterlace
-    end
-
-    image.destroy!
     output_file
   end
-
-  def flatten(image, width, height)
-    if image.alpha?
-      # since jpeg can't represent transparency, we need to create an image list,
-      # put a white image on the bottom, then flatten it.
-
-      list = Magick::ImageList.new
-      list.new_image(width, height) do
-        self.background_color = "#FFFFFF"
-      end
-      list << image
-      flattened_image = list.flatten_images
-      list.each do |image|
-        image.destroy!
-      end
-      return flattened_image
-    else
-      return image
-    end
-  end
-
-  module_function :resize, :flatten
 end

app/models/upload.rb

@@ -226,7 +226,17 @@ class Upload < ApplicationRecord
     end
 
     def is_animated_gif?
-      file_ext == "gif" && Magick::Image.ping(file.path).length > 1
+      return false if file_ext != "gif"
+
+      # Check whether the gif has multiple frames by trying to load the second frame.
+      result = Vips::Image.gifload(file.path, page: 1) rescue $ERROR_INFO
+      if result.is_a?(Vips::Image)
+        true
+      elsif result.is_a?(Vips::Error) && result.message.match?(/too few frames in GIF file/)
+        false
+      else
+        raise result
+      end
     end
 
     def is_animated_png?
@@ -245,7 +255,7 @@ class Upload < ApplicationRecord
         preview_file = DanbooruImageResizer.resize(file, Danbooru.config.small_image_width, Danbooru.config.small_image_width, 85)
 
         if image_width > Danbooru.config.large_image_width
-          sample_file = DanbooruImageResizer.resize(file, Danbooru.config.large_image_width, nil, 90)
+          sample_file = DanbooruImageResizer.resize(file, Danbooru.config.large_image_width, image_height, 90)
         end
       end