gems: drop ruby-imagespec gem.

* Use libvips instead of ruby-imagespec for reading dimensions of jpeg, png, and gif files.
* Copy the code for reading the dimensions of flash files from ruby-imagespec.

Fixes an incompatibility between ruby-imagespec and the rubocop gem that
prevented us from including rubocop in the Gemfile.

Gemfile

@@ -48,9 +48,6 @@ gem 'activerecord-hierarchical_query'
 gem 'pundit'
 gem 'mail'
 
-# needed for looser jpeg header compat
-gem 'ruby-imagespec', :require => "image_spec", :git => "https://github.com/r888888888/ruby-imagespec.git", :branch => "exif-fixes"
-
 group :production, :staging do
   gem 'unicorn', :platforms => :ruby
   gem 'capistrano3-unicorn'

Gemfile.lock

@@ -5,13 +5,6 @@ GIT
     dtext_rb (1.10.5)
       nokogiri (~> 1.8)
 
-GIT
-  remote: https://github.com/r888888888/ruby-imagespec.git
-  revision: 2dab9811f4abb4fbaeea66feb42e388ba545b2d8
-  branch: exif-fixes
-  specs:
-    ruby-imagespec (0.3.1)
-
 GEM
   remote: https://rubygems.org/
   specs:
@@ -456,7 +449,6 @@ DEPENDENCIES
   request_store
   responders
   retriable
-  ruby-imagespec!
   ruby-vips
   rubyzip
   sanitize

app/logical/media_file/flash.rb

@@ -1,6 +1,57 @@
+# Adapted from https://github.com/dim/ruby-imagespec/blob/f2f3ce8bb5b1b411f8658e66a891a095261d94c0/lib/image_spec/parser/swf.rb
+# License: https://github.com/dim/ruby-imagespec/blob/master/LICENSE
+
 class MediaFile::Flash < MediaFile::Image
   def dimensions
-    image_size = ImageSpec.new(file.path)
-    [image_size.width, image_size.height]
+    # Read the entire stream into memory because the
+    # dimensions aren't stored in a standard location
+    contents = file.read.force_encoding("ASCII-8BIT")
+
+    # Our 'signature' is the first 3 bytes
+    # Either FWS or CWS.  CWS indicates compression
+    signature = contents[0..2]
+
+    # SWF version
+    version = contents[3].unpack('C').join.to_i
+
+    # Determine the length of the uncompressed stream
+    length = contents[4..7].unpack('V').join.to_i
+
+    # If we do, in fact, have compression
+    if signature == 'CWS'
+      # Decompress the body of the SWF
+      body = Zlib::Inflate.inflate( contents[8..length] )
+
+      # And reconstruct the stream contents to the first 8 bytes (header)
+      # Plus our decompressed body
+      contents = contents[0..7] + body
+    end
+
+    # Determine the nbits of our dimensions rectangle
+    nbits = contents.unpack('C'*contents.length)[8] >> 3
+
+    # Determine how many bits long this entire RECT structure is
+    rectbits = 5 + nbits * 4    # 5 bits for nbits, as well as nbits * number of fields (4)
+
+    # Determine how many bytes rectbits composes (ceil(rectbits/8))
+    rectbytes = (rectbits.to_f / 8).ceil
+
+    # Unpack the RECT structure from the stream in little-endian bit order, then join it into a string
+    rect = contents[8..(8 + rectbytes)].unpack("#{'B8' * rectbytes}").join
+
+    # Read in nbits incremenets starting from 5
+    dimensions = Array.new
+    4.times do |n|
+      s = 5 + (n * nbits)     # Calculate our start index
+      e = s + (nbits - 1)     # Calculate our end index
+      dimensions[n] = rect[s..e].to_i(2)    # Read that range (binary) and convert it to an integer
+    end
+
+    # The values we have here are in "twips"
+    # 20 twips to a pixel (that's why SWFs are fuzzy sometimes!)
+    width = (dimensions[1] - dimensions[0]) / 20
+    height = (dimensions[3] - dimensions[2]) / 20
+
+    [width, height]
   end
 end

app/logical/media_file/image.rb

@@ -1,6 +1,9 @@
 class MediaFile::Image < MediaFile
   def dimensions
-    image_size = ImageSpec.new(file.path)
-    [image_size.width, image_size.height]
+    image.size
+  end
+
+  def image
+    @image ||= Vips::Image.new_from_file(file.path)
   end
 end