start work on better packing algorithm, start with scan

Gemfile.lock

@@ -7,7 +7,7 @@ GIT
 PATH
   remote: .
   specs:
-    compass (0.11.1.d9e4054)
+    compass (0.11.1.d9ca08f)
       chunky_png (~> 1.1)
       fssm (>= 0.2.7)
       sass (~> 3.1)
@@ -50,7 +50,7 @@ GEM
     autotest-fsevent (0.2.5)
       sys-uname
     builder (2.1.2)
-    chunky_png (1.1.1)
+    chunky_png (1.2.0)
     compass-validator (3.0.0)
     css_parser (1.0.1)
     cucumber (0.9.4)

lib/compass/sass_extensions/sprites/image_group.rb

@@ -0,0 +1,18 @@
+module Compass
+  module SassExtensions
+    module Sprites
+      class ImageGroup
+        attr_reader :images
+
+        def initialize(images = [])
+          @images = images
+        end
+
+        def best_fitting_rows
+          
+        end
+      end
+    end
+  end
+end
+

lib/compass/sass_extensions/sprites/image_row.rb

@@ -1,8 +1,13 @@
+require 'forwardable'
+
 module Compass
   module SassExtensions
     module Sprites
       class ImageRow
+        extend Forwardable
+
         attr_reader :images, :max_width
+        def_delegators :@images, :last, :delete, :empty?, :length
         
         def initialize(max_width)
           @images = []
@@ -10,16 +15,13 @@ module Compass
         end
         
         def add(image)
-          unless image.is_a?(Compass::SassExtensions::Sprites::Image)
+          return false if !will_fit?(image)
-            raise ArgumentError, "Must be a SpriteImage"
-          end
-          if (images.inject(0) {|sum, img| sum + img.width} + image.width) > max_width
-            return false
-          end
           @images << image
           true
         end
 
+        alias :<< :add
+        
         def height
           images.map(&:height).max
         end
@@ -28,6 +30,17 @@ module Compass
           images.map(&:width).max
         end
 
+        def total_width
+          images.inject(0) {|sum, img| sum + img.width }
+        end
+        
+        def efficiency
+          1 - (total_width.to_f / max_width.to_f)
+        end
+
+        def will_fit?(image)
+          (total_width + image.width) <= max_width
+        end
       end
     end
   end

lib/compass/sass_extensions/sprites/row_fitter.rb

@@ -0,0 +1,81 @@
+require 'forwardable'
+
+module Compass
+  module SassExtensions
+    module Sprites
+      class RowFitter
+        extend Forwardable
+
+        attr_reader :images, :rows
+        def_delegators :rows, :[]
+        def initialize(images)
+          @images = images
+          @rows = []
+        end
+
+        def fit!(style = :scan)
+          send("#{style}_fit")
+        end
+
+        def width
+          @width ||= @images.collect(&:width).max
+        end
+
+        def efficiency
+          @rows.inject(0) { |sum, row| sum += row.efficiency } ** @rows.length
+        end
+
+        private
+        def new_row(image = nil)
+          row = Compass::SassExtensions::Sprites::ImageRow.new(width)
+          row.add(image) if image
+          row
+        end
+
+        def fast_fit
+          row = new_row
+          @images.each do |image|
+            if !row.add(image)
+              @rows << row
+              row = new_row(image)
+            end
+          end
+
+          @rows << row
+        end
+
+        def scan_fit
+          fast_fit
+
+          moved_images = []
+
+          begin
+            removed = false
+
+            catch :done do
+              @rows.each do |row|
+                (@rows - [ row ]).each do |other_row|
+                  other_row.images.each do |image|
+                    if !moved_images.include?(image)
+                      if row.will_fit?(image)
+                        other_row.delete(image)
+                        row << image
+
+                        @rows.delete(other_row) if other_row.empty?
+                        removed = true
+
+                        moved_images << image
+                        throw :done
+                      end
+                    end
+                  end
+                end
+              end
+            end
+          end while removed
+        end
+      end
+    end
+  end
+end
+

test.watchr

@@ -0,0 +1,7 @@
+watch('test/(.*)_test\.rb') { |m| test(m[0]) }
+watch('lib/compass/sass_extensions/sprites/image_group.rb') { test('test/units/sprites/image_group_test.rb') }
+watch('lib/compass/sass_extensions/sprites/row_fitter.rb') { test('test/units/sprites/row_fitter_test.rb') }
+
+def test(file = nil)
+  system %{ruby -I"lib:test" #{file}}.tap { |o| puts o }
+end

test/test_helper.rb

@@ -21,7 +21,7 @@ require 'rubygems' if need_gems
 require 'compass'
 
 require 'test/unit'
-
+require 'mocha'
 
 %w(command_line diff io rails test_case).each do |helper|
   require "helpers/#{helper}"

test/units/sprites/image_group_test.rb

@@ -0,0 +1,9 @@
+require 'test_helper'
+require 'compass/sass_extensions/sprites/image_group'
+
+class ImageGroupTest < Test::Unit::TestCase
+  def setup
+  end
+
+end
+

test/units/sprites/image_row_test.rb

@@ -49,4 +49,8 @@ class ImageRowTest < Test::Unit::TestCase
     assert_equal 40, @image_row.height
   end
   
+  it "should have an efficiency rating" do
+    populate_row
+    assert_equal 1 - (580.0 / 1000.0), @image_row.efficiency
+  end
 end

test/units/sprites/row_fitter_test.rb

@@ -0,0 +1,82 @@
+require 'test_helper'
+require 'compass/sass_extensions/sprites/row_fitter'
+
+class RowFitterTest < Test::Unit::TestCase
+  def setup
+  end
+
+  def row_fitter(images = nil)
+    @row_fitter ||= Compass::SassExtensions::Sprites::RowFitter.new(images)
+  end
+
+  def teardown
+    @row_fitter = nil
+  end
+
+  def create_images(dims)
+    dims.collect { |width, height| stub(:width => width, :height => height) }
+  end
+
+  def basic_dims
+    [
+      [ 100, 10 ],
+      [ 80, 10 ],
+      [ 50, 10 ],
+      [ 20, 10 ],
+      [ 35, 10 ]
+    ]
+  end
+
+  it 'should use the fast placement algorithm' do
+    images = create_images(basic_dims)
+
+    row_fitter(images)
+    assert_equal 100, row_fitter.width
+
+    row_fitter.fit!(:fast)
+
+    assert_equal 4, row_fitter.rows.length
+
+    assert_equal [ images[0] ], row_fitter[0].images
+    assert_equal [ images[1] ], row_fitter[1].images
+    assert_equal [ images[2], images[3] ], row_fitter[2].images
+    assert_equal [ images[4] ], row_fitter[3].images
+  end
+
+  it 'should use the scan placement algorithm' do
+    images = create_images(basic_dims)
+
+    row_fitter(images)
+
+    row_fitter.fit!(:scan)
+
+    assert_equal 3, row_fitter.rows.length
+
+    assert_equal [ images[0] ], row_fitter[0].images
+    assert_equal [ images[1], images[3] ], row_fitter[1].images
+    assert_equal [ images[2], images[4] ], row_fitter[2].images
+  end
+
+  it 'should use the scan placement algorithm and get images from the front' do
+    images = create_images(
+      [
+        [ 100, 10 ],
+        [ 35, 10 ],
+        [ 80, 10 ],
+        [ 50, 10 ],
+        [ 20, 10 ],
+      ]
+    )
+
+    row_fitter(images)
+
+    row_fitter.fit!(:scan)
+
+    assert_equal 3, row_fitter.rows.length
+
+    assert_equal [ images[0] ], row_fitter[0].images
+    assert_equal [ images[1], images[3] ], row_fitter[1].images
+    assert_equal [ images[2], images[4] ], row_fitter[2].images
+  end
+end
+