Background configurarion for images with alpha channels

config.ru

@@ -1,9 +1,13 @@
 # -*- encoding: utf-8 -*-
-$:.unshift(::File.expand_path(::File.join(::File.dirname(__FILE__), 'lib')))
-require 'mugshot'
+$:.unshift(::File.expand_path(::File.join(::File.dirname(__FILE__), "lib")))
+require "mugshot"
 
-system "mkdir -p /tmp/mugshot && cp -f spec/files/test.jpg /tmp/mugshot/test"
+system "mkdir -p /tmp/mugshot"
+%w[test.jpg with_alpha_channel.png].each do |filename|
+  system "cp -f features/support/files/#{filename} /tmp/mugshot/#{filename.split('.').first}"
+end
 
 run Mugshot::Application.new(
-  :storage => Mugshot::ProxyStorage.new{|id| "http://foo.com/#{id}.jpg"}
+  :storage => Mugshot::FSStorage.new("/tmp/mugshot")
 )
+

cucumber.yml

@@ -1 +1 @@
-default: -r features/support/env.rb -r features/step_definitions
+default: --guess -r features/support/env.rb -r features/step_definitions

features/image_format.feature

@@ -9,3 +9,8 @@ Feature: Image Format
     When I upload an image
     And I ask for a jpg image
     Then I should get a jpg image
+
+  Scenario: Image as png
+    When I upload an image
+    And I ask for a png image
+    Then I should get a png image

features/set_background.feature

@@ -0,0 +1,7 @@
+Feature: Set Background
+
+  Scenario: Set background for a png image with alpha channel
+    Given a png image with alpha channel
+    When I ask for it with a red background
+    Then I should get it with a red background
+

features/step_definitions/all_steps.rb

@@ -1,4 +1,22 @@
 # -*- encoding: utf-8 -*-
+Given /^a (.*) image (.*)$/ do |ext, name|
+  @image = {
+    :name => name,
+    :ext => ext,
+    :filename => "#{name.gsub(' ', '_')}.#{ext}"}
+
+  @image[:id] = write_image(@image[:filename])
+end
+
+When /^I ask for it with a (.*) background$/ do |color|
+  get "/background/#{color}/#{@image[:id]}/img.jpg"
+  @retrieved_image = Magick::Image.from_blob(last_response.body).first
+end
+
+Then /^I should get it (.*)$/ do |name|
+  @retrieved_image.should be_same_image_as("#{@image[:name].gsub(' ', '_')}-#{name.underscore.gsub(' ', '_')}.jpg")
+end
+
 When /^I upload an image$/ do
   post '/', "file" => Rack::Test::UploadedFile.new("features/support/files/test.jpg", "image/jpeg")
   @image_id = last_response.body

features/support/env.rb

@@ -17,6 +17,11 @@ module CucumberWorld
   def app
     Mugshot::Application.new(Mugshot::FSStorage.new('/tmp/mugshot/cucumber'))
   end
+
+  def write_image(filename)
+    Mugshot::FSStorage.new('/tmp/mugshot/cucumber').
+      write(IO.read(File.expand_path(filename, "features/support/files/")))
+  end
 end
 World(CucumberWorld)
 

lib/mugshot.rb

@@ -7,4 +7,5 @@ module Mugshot
   autoload :FSStorage, "mugshot/fs_storage"
   autoload :Application, "mugshot/application"
   autoload :HTTPStorage, "mugshot/http_storage"
+  autoload :MagickFactory, "mugshot/magick_factory"
 end

lib/mugshot/application.rb

@@ -2,6 +2,9 @@
 require 'sinatra/base'
 
 class Mugshot::Application < Sinatra::Base
+
+  VALID_OPERATIONS = %w[background crop resize quality]
+
   set :static, true
   set :public, ::File.expand_path(::File.join(::File.dirname(__FILE__), "public"))
 
@@ -36,19 +39,22 @@ def initialize(opts)
     opts.to_options!
 
     @storage = opts[:storage]
+
+    @background = opts[:background].to_s if opts.include?(:background)
     @quality = opts[:quality].to_s if opts.include?(:quality)
   end
 
   private
   def process_default_operations(image)
+    image.background!(@background) if !!@background
     image.quality!(@quality) if !!@quality
   end
 
   def process_operations(image, splat)
     operations = []
     begin
       operations = Hash[*splat.split('/')]
-      operations.assert_valid_keys("crop", "resize", "quality")
+      operations.assert_valid_keys(VALID_OPERATIONS)
     rescue
       halt 404
     end

lib/mugshot/http_storage.rb

@@ -4,6 +4,7 @@
 require 'net/http'
 
 class Mugshot::HTTPStorage < Mugshot::Storage
+
   def read(id)
     url = URI.parse(@url_resolver.call(id))
     res = Net::HTTP.start(url.host, url.port) {|http| http.get(url.path)}

lib/mugshot/image.rb

@@ -1,12 +1,9 @@
 # -*- encoding: utf-8 -*-
 require 'RMagick'
 class Mugshot::Image
-  def width
-    @image.columns
-  end
 
-  def height
-    @image.rows
+  def background!(color)
+    @background_color = color
   end
 
   def resize!(size)
@@ -38,6 +35,9 @@ def destroy!
 
   def to_blob(opts = {})
     opts.merge!(:quality => @quality)
+
+    set_background(@background_color) if !!@background_color
+
     @image.strip!
     @image.to_blob do
       self.format = opts[:format].to_s if opts.include?(:format)
@@ -54,12 +54,18 @@ def initialize(file_or_blob)
     end
 
     # initialize attrs
-    @quality = nil
+    @background_color = @quality = nil
   end
 
   private
-
   def parse_size(size)
     size.to_s.split("x").map{|i| i.blank? ? nil : i.to_i}
   end
+
+  def set_background(color)
+    @image = Mugshot::MagickFactory.
+      create_canvas(@image.columns, @image.rows, color).
+      composite(@image, Magick::NorthWestGravity, Magick::OverCompositeOp)
+  end
 end
+

lib/mugshot/magick_factory.rb

@@ -0,0 +1,12 @@
+# -*- encoding: utf-8 -*-
+require 'RMagick'
+
+class Mugshot::MagickFactory
+  class << self
+
+    def create_canvas(columns, rows, color)
+      Magick::Image.new(columns, rows){ self.background_color = color }
+    end
+
+  end
+end

spec/mugshot/application_spec.rb

@@ -20,6 +20,14 @@ def app
       @image.should_receive(:quality!).with("42")
       get "/image_id/any_name.jpg"
     end
+
+    it "should accept default value for background" do
+      def app
+        Mugshot::Application.new(:storage => @storage, :background => 'blue')
+      end
+      @image.should_receive(:background!).with("blue")
+      get "/image_id/any_name.jpg"
+    end
   end
 
   describe "POST /" do
@@ -70,8 +78,9 @@ def app
       @image.should_receive(:resize!).with("140x140")
       @image.should_receive(:crop!).with("140x105")
       @image.should_receive(:quality!).with("70")
+      @image.should_receive(:background!).with("red")
 
-      get "/resize/140x140/crop/140x105/quality/70/image_id/any_name.jpg"
+      get "/background/red/resize/140x140/crop/140x105/quality/70/image_id/any_name.jpg"
     end
 
     it "should halt 404 on operations that are not allowed" do

spec/mugshot/image_spec.rb

@@ -3,8 +3,7 @@
 
 describe Mugshot::Image do
   before :each do
-    @magick_image = mock(Magick::Image)
-    @magick_image.stub!(:strip!)
+    @magick_image = mock(Magick::Image, :null_object => true, :columns => 100, :rows => 100)
     @magick_image.instance_eval do # TODO: Explain it
       def to_blob(&block)
         block.call if block.present?
@@ -22,14 +21,6 @@ def to_blob(&block)
     Mugshot::Image.new("blob")
   end
 
-  it 'should return image width and height' do
-    @magick_image.stub!(:columns).and_return(100)
-    @magick_image.stub!(:rows).and_return(200)
-
-    @image.width.should == 100
-    @image.height.should == 200
-  end
-
   describe "to blob" do
     it 'should return image as a blob using default options' do
       @image.to_blob.should == 'blob_data'
@@ -47,6 +38,17 @@ def to_blob(&block)
     @image.quality!("75")
     @image.to_blob
   end
+
+  it 'should set background for transparent images' do
+    canvas = mock(Magick::Image)
+    Mugshot::MagickFactory.stub!(:create_canvas).and_return(canvas)
+    canvas.should_receive(:composite).
+      with(@magick_image, Magick::NorthWestGravity, Magick::OverCompositeOp).
+      and_return(@magick_image)
+
+    @image.background!("gray")
+    @image.to_blob
+  end
 
   it "should resize image to given width and height" do
     @magick_image.should_receive(:resize!).with(300, 200)
@@ -74,3 +76,4 @@ def to_blob(&block)
   end
 
 end
+

spec/mugshot/magick_factory_spec.rb

@@ -0,0 +1,13 @@
+# -*- encoding: utf-8 -*-
+require File.expand_path(File.dirname(__FILE__) + '/../spec_helper')
+
+describe Mugshot::MagickFactory do
+
+  it "should create a canvas given columns, rows and background color" do
+    canvas = Mugshot::MagickFactory.create_canvas(100, 200, 'red')
+    canvas.columns.should == 100
+    canvas.rows.should == 200
+    canvas.background_color == 'red'
+  end
+
+end