auto-orient option added

This adds a auto-orient option, which is enabled by default. I believe, most users expect their images to be rotated according to EXIF. The photo I've added to the fixtures was token by myself, I release it to the public domain.

lib/paperclip/thumbnail.rb

@@ -3,7 +3,7 @@ module Paperclip
   class Thumbnail < Processor
 
     attr_accessor :current_geometry, :target_geometry, :format, :whiny, :convert_options,
-                  :source_file_options, :animated
+                  :source_file_options, :animated, :auto_orient
 
     # List of formats that we need to preserve animation
     ANIMATED_FORMATS = %w(gif)
@@ -38,6 +38,7 @@ module Paperclip
       @whiny               = options[:whiny].nil? ? true : options[:whiny]
       @format              = options[:format]
       @animated            = options[:animated].nil? ? true : options[:animated]
+      @auto_orient         = options[:auto_orient].nil? ? true : options[:auto_orient]
 
       @source_file_options = @source_file_options.split(/\s+/) if @source_file_options.respond_to?(:split)
       @convert_options     = @convert_options.split(/\s+/)     if @convert_options.respond_to?(:split)
@@ -89,6 +90,7 @@ module Paperclip
       scale, crop = @current_geometry.transformation_to(@target_geometry, crop?)
       trans = []
       trans << "-coalesce" if animated?
+      trans << "-auto-orient" if auto_orient
       trans << "-resize" << %["#{scale}"] unless scale.nil? || scale.empty?
       trans << "-crop" << %["#{crop}"] << "+repage" if crop
       trans

test/thumbnail_test.rb

@@ -114,7 +114,7 @@ class ThumbnailTest < Test::Unit::TestCase
 
       should "send the right command to convert when sent #make" do
         @thumb.expects(:convert).with do |*arg|
-          arg[0] == ':source -resize "x50" -crop "100x50+114+0" +repage :dest' &&
+          arg[0] == ':source -auto-orient -resize "x50" -crop "100x50+114+0" +repage :dest' &&
           arg[1][:source] == "#{File.expand_path(@thumb.file.path)}[0]"
         end
         @thumb.make
@@ -139,7 +139,7 @@ class ThumbnailTest < Test::Unit::TestCase
 
       should "send the right command to convert when sent #make" do
         @thumb.expects(:convert).with do |*arg|
-          arg[0] == '-strip :source -resize "x50" -crop "100x50+114+0" +repage :dest' &&
+          arg[0] == '-strip :source -auto-orient -resize "x50" -crop "100x50+114+0" +repage :dest' &&
           arg[1][:source] == "#{File.expand_path(@thumb.file.path)}[0]"
         end
         @thumb.make
@@ -180,7 +180,7 @@ class ThumbnailTest < Test::Unit::TestCase
 
       should "send the right command to convert when sent #make" do
         @thumb.expects(:convert).with do |*arg|
-          arg[0] == ':source -resize "x50" -crop "100x50+114+0" +repage -strip -depth 8 :dest' &&
+          arg[0] == ':source -auto-orient -resize "x50" -crop "100x50+114+0" +repage -strip -depth 8 :dest' &&
           arg[1][:source] == "#{File.expand_path(@thumb.file.path)}[0]"
         end
         @thumb.make
@@ -302,6 +302,62 @@ class ThumbnailTest < Test::Unit::TestCase
     end
   end
 
+  context "An image with exif orientation" do
+    setup do
+      @file = File.new(fixture_file("rotated.jpg"), 'rb')
+    end
+
+    teardown { @file.close }
+
+    context "With :auto_orient => false" do
+      setup do
+        @thumb = Paperclip::Thumbnail.new(@file, :geometry => "100x50", :auto_orient => false)
+      end
+
+      should "send the right command to convert when sent #make" do
+        @thumb.expects(:convert).with do |*arg|
+          arg[0] == ':source -resize "100x50" :dest' &&
+              arg[1][:source] == "#{File.expand_path(@thumb.file.path)}[0]"
+        end
+        @thumb.make
+      end
+
+      should "create the thumbnail when sent #make" do
+        dst = @thumb.make
+        assert_match /75x50/, `identify "#{dst.path}"`
+      end
+
+      should "not touch the orientation information" do
+        dst = @thumb.make
+        assert_match /exif:Orientation=6/, `identify -format "%[EXIF:*]" "#{dst.path}"`
+      end
+    end
+
+    context "Without :auto_orient => false" do
+      setup do
+        @thumb = Paperclip::Thumbnail.new(@file, :geometry => "100x50")
+      end
+
+      should "send the right command to convert when sent #make" do
+        @thumb.expects(:convert).with do |*arg|
+          arg[0] == ':source -auto-orient -resize "100x50" :dest' &&
+              arg[1][:source] == "#{File.expand_path(@thumb.file.path)}[0]"
+        end
+        @thumb.make
+      end
+
+      should "create the thumbnail when sent #make" do
+        dst = @thumb.make
+        assert_match /33x50/, `identify "#{dst.path}"`
+      end
+
+      should "remove the orientation information" do
+        dst = @thumb.make
+        assert_match /exif:Orientation=1/, `identify -format "%[EXIF:*]" "#{dst.path}"`
+      end
+    end
+  end
+
   context "A multipage PDF" do
     setup do
       @file = File.new(fixture_file("twopage.pdf"), 'rb')