README improved

README.rdoc

@@ -11,14 +11,6 @@ Add the following line to your Gemfile:
     include CarrierWave::RMagick
     include CarrierWave::Meta
 
-    def store_dir
-      "tmp/store"
-    end
-
-    def cache_dir
-      "tmp/cache"
-    end
-
     storage :file
 
     process :store_meta
@@ -87,8 +79,136 @@ content type.
 
 Uploader tries to retrieve metadata from a model's column first.
 
-= Integrating CarrierWave & JCrop using carrierwave-meta
+= model_delegate_attribute
+
+  class DelegateTestModel
+    attr_accessor :processed
+    attr_accessor :a_processed
+    attr_accessor :a_b_processed
+  end
+
+  class DelegateTestUploader < CarrierWave::Uploader::Base
+    model_delegate_attribute :uploaded
+
+    set_processed
+
+    version :a do
+      set_processed
+      version :b do
+        set_processed
+      end
+    end
+
+    def set_processed
+      self.processed = true
+    end
+  end
+
+  model = DelegateTestModel.new
+  uploader = DelegateTestUploader.new(model, :image)
+  file = File.open('test.jpg')
+
+  uploader.store!(file)
+
+  model.processed     # true
+  model.a_processed   # true  
+  model.a_b_processed # true
+
+  model.a_processed = false
+
+  uploader.processed     # true
+  uploader.a_processed   # false
+  uploader.a_b_processed # true
 
+Is used to synchronize data between uploader and mounted model. Model is used like values cache.
+
+When model is mounted to uploader:
+
+1. When assigned inside uploader, assigns corresponding property in model.
+2. When retrieved from uploader instance first checks if value is defined in model and returns it. Otherwise returns uploader's instance variable.
+3. When file is deleted, value becomes nil.
+
+Otherwise acts as regular uploader's instance variables.
+
+This is very useful for:
+
+= Integrating CarrierWave with JCrop
+
+Let implement the behavior like at this demo: http://deepliquid.com/projects/Jcrop/demos.php?demo=thumbnail
+
+The uploader:
+
+  class PostImageUploader < SobakaUploader
+    include CarrierWave::Meta
+
+    # Crop source is a source image converted from original (left image in the example).
+    version :crop_source do
+      process :resize_to_fit => [538, 538]
+      process :store_meta
+
+      # This is the cropped version of parent image. Let crop to 50x50 square.
+      version :big do
+        process :crop_to => [50, 50]
+      end
+    end
+
+    # Defines crop area dimensions.
+    # This should be assigned before store! and cache! called and should be saved in the model's instance. 
+    # If crop ared dimensions are'nt assigned, uploader creates default cropped image and saves it's dimensions.
+    # Otherwise cropped image would be lost after recreate_versions! is called.
+    model_delegate_attribute :x
+    model_delegate_attribute :y
+    model_delegate_attribute :w
+    model_delegate_attribute :h
+
+    def crop_to(width, height)
+      # Checks that crop area is defined and crop should be done.
+      if ((crop_args[0] == crop_args[2]) || (crop_args[1] == crop_args[3]))
+        # If not creates default image and saves it's dimensions.
+        resize_to_fill_and_save_dimensions(width, height)
+      else
+        args = crop_args + [width, height]
+        crop_and_resize(*args)
+      end
+    end
+
+    def crop_and_resize(x, y, width, height, new_width, new_height)
+      manipulate! do |img|
+        cropped_img = img.crop(x, y, width, height)
+        new_img = cropped_img.resize_to_fill(new_width, new_height)
+        destroy_image(cropped_img)
+        destroy_image(img)      
+        new_img
+      end
+    end
+
+    # Creates the default crop image.
+    # Here the original cropped image dimensions are restored and assigned to the model's instance.  
+    def resize_to_fill_and_save_dimensions(new_width, new_height)
+      manipulate! do |img|
+        width, height = img.columns, img.rows
+        new_img = img.resize_to_fill(new_width, new_height)
+        destroy_image(img)
+
+        w_ratio = width.to_f / new_width.to_f
+        h_ratio = height.to_f / new_height.to_f
+
+        ratio = [w_ratio, h_ratio].min
+
+        self.w = ratio * new_width
+        self.h = ratio * new_height
+        self.x = (width - self.w) / 2
+        self.y = (height - self.h) / 2
+
+        new_img
+      end
+    end
+
+    private
+    def crop_args
+      %w(x y w h).map { |accessor| send(accessor).to_i }
+    end    
+  end
 
 = TODO