Use chunky_png instead of rmagick to get rid of imagemagick dependencies

Gemfile

@@ -1,7 +1,7 @@
 source "http://rubygems.org"
 
 gem "colored"
-gem "rmagick"
+gem "chunky_png"
 
 group :test do
   gem "cucumber", "0.10.2"

Gemfile.lock

@@ -20,6 +20,7 @@ GEM
     celerity (0.8.9)
     childprocess (0.1.9)
       ffi (~> 1.0.6)
+    chunky_png (1.2.0)
     colored (1.2)
     cucumber (0.10.2)
       builder (>= 2.1.2)
@@ -39,7 +40,6 @@ GEM
     rack (1.2.2)
     rack-test (0.6.0)
       rack (>= 1.0)
-    rmagick (2.13.1)
     rspec (2.6.0)
       rspec-core (~> 2.6.0)
       rspec-expectations (~> 2.6.0)
@@ -65,7 +65,7 @@ DEPENDENCIES
   aruba (= 0.3.6)
   capybara (= 0.4.1.2)
   capybara-webkit (= 0.3.0)
+  chunky_png
   colored
   cucumber (= 0.10.2)
-  rmagick
   rspec (= 2.6.0)

lib/blueprint/compressor.rb

@@ -143,12 +143,7 @@ def generate_css_files
       # append semantic class names if set
       append_semantic_classes
 
-      #attempt to generate a grid.png file
-      if (grid_builder = GridBuilder.new(:column_width => self.custom_layout.column_width,
-                                         :gutter_width => self.custom_layout.gutter_width,
-                                         :output_path => File.join(self.destination_path, "src")))
-        grid_builder.generate!
-      end
+      generate_grid_png
     end
 
     def append_custom_css(css, current_file_name)
@@ -242,6 +237,12 @@ def generate_tests
       end
     end
 
+    def generate_grid_png
+      GridBuilder.new(:column_width => self.custom_layout.column_width,
+                      :gutter_width => self.custom_layout.gutter_width,
+                      :output_path  => File.join(self.destination_path, "src")).generate!
+    end
+
     def output_header
       puts "\n"
       puts "  #{"*" * 100}"

lib/blueprint/grid_builder.rb

@@ -1,24 +1,5 @@
-begin
-  require "rmagick"
-  require "rvg/rvg"
-rescue Exception => e
-  puts "  #{"*" * 100}".red
-  puts "  **".red
-  puts "  **   Warning:".red
-  puts "  **   Could not load the Rmagick gem.  Please check your installation.".red
-  puts "  **   grid.png will not be generated.".red
-  puts "  **".red
-  puts "  #{"*" * 100}\n".red
-end
-
 module Blueprint
-  # Uses ImageMagick and RMagick to generate grid.png file
   class GridBuilder
-    begin
-      include Magick
-    rescue Exception => e
-    end
-
     attr_reader :column_width, :gutter_width, :output_path, :able_to_generate
 
     # ==== Options
@@ -27,36 +8,26 @@ class GridBuilder
     #   * <tt>:gutter_width</tt> -- Width (in pixels) of current grid gutter
     #   * <tt>:output_path</tt> -- Output path of grid.png file
     def initialize(options={})
-      @able_to_generate = Magick::Long_version rescue false
-      return unless @able_to_generate
       @column_width = options[:column_width] || Blueprint::COLUMN_WIDTH
       @gutter_width = options[:gutter_width] || Blueprint::GUTTER_WIDTH
       @output_path  = options[:output_path]  || Blueprint::SOURCE_PATH
     end
 
     # generates (overwriting if necessary) grid.png image to be tiled in background
     def generate!
-      return false unless self.able_to_generate
       total_width = self.column_width + self.gutter_width
-      height = 18
-      RVG::dpi = 100
-
-      width_in_inches = (total_width.to_f/RVG::dpi).in
-      height_in_inches = (height.to_f/RVG::dpi).in
-      rvg = RVG.new(width_in_inches, height_in_inches).viewbox(0, 0, total_width, height) do |canvas|
-        canvas.background_fill = "white"
+      height      = 18
 
-        canvas.g do |column|
-          column.rect(self.column_width - 1, height).styles(:fill => "#e8effb")
-        end
+      white      = ChunkyPNG::Color.from_hex("ffffff")
+      background = ChunkyPNG::Color.from_hex("e8effb")
+      line       = ChunkyPNG::Color.from_hex("e9e9e9")
 
-        canvas.g do |baseline|
-          baseline.line(0, (height - 1), total_width, (height - 1)).styles(:fill => "#e9e9e9")
-        end
-      end
+      png = ChunkyPNG::Image.new(total_width, height, white)
+      png.rect(0, 0, column_width - 1, height, background, background)
+      png.rect(0, height - 1, total_width, height - 1, line, line)
 
-      FileUtils.mkdir self.output_path unless File.exists? self.output_path
-      rvg.draw.write(File.join(self.output_path, "grid.png"))
+      FileUtils.mkdir(self.output_path) unless File.exists?(self.output_path)
+      png.save(File.join(self.output_path, "grid.png"))
     end
   end
 end