Implement Imagery#update_size.

lib/imagery.rb

@@ -75,7 +75,19 @@ def save(io, key = nil)
         GM.convert root(ext(@original)), root(ext(size)), resize, extent
       end
     end
-
+
+    # Updates a certain size (`size`) with another file.
+    #
+    # The second parameter `io` can be a File IO, or a filename string.
+    def update_size(size, io)
+      resize, extent = sizes[size.to_sym]
+      filename = io.respond_to?(:path) ? io.path : io.to_s
+
+      if resize && File.exist?(filename)
+        GM.convert filename, root(ext(size)), resize, extent
+      end
+    end
+
     # A very simple and destructive method. Deletes the entire folder
     # for the current prefix/key combination.
     def delete

lib/imagery/faking.rb

@@ -79,6 +79,14 @@ def save(io, key = nil)
       super
     end
 
+    # Implement the stubbed version of save and skips actual operation
+    # if Imagery::Model.mode == :fake
+    def update_size(size, io)
+      return true if self.class.mode == :fake
+
+      super
+    end
+
     # Implement the stubbed version of save and skips actual operation
     # if Imagery::Model.mode == :fake
     def delete

lib/imagery/s3.rb

@@ -77,15 +77,24 @@ def delete
     def save(io, key = nil)
       super
 
-      keys.each do |file|
-        Gateway.store(s3_key(file),
-          File.open(root(ext(file))),
-          self.class.s3_bucket,
-          :access => :public_read,
-          :content_type => "image/jpeg",
-          "Cache-Control" => "max-age=315360000"
-        )
-      end
+      keys.each { |file| store file }
+    end
+
+    def update_size(size, io)
+      super
+
+      store size
+    end
+
+  private
+    def store(file)
+      Gateway.store(s3_key(file),
+        File.open(root(ext(file))),
+        self.class.s3_bucket,
+        :access => :public_read,
+        :content_type => "image/jpeg",
+        "Cache-Control" => "max-age=315360000"
+      )
     end
 
     # Provides a convenience wrapper around AWS::S3::S3Object and

test/helper.rb

@@ -3,6 +3,10 @@
 require "cutest"
 require "imagery"
 
+def assert_equal(left, right)
+  assert left == right
+end
+
 def fixture(filename)
   File.expand_path("fixtures/#{filename}", File.dirname(__FILE__))
 end

test/imagery.rb

@@ -112,6 +112,20 @@
     # Like small.jpg, it will be resized to fit within 30x30
     assert_equal "30x23", resolution(im.root("tiny.jpg"))
   end
+
+  test "update a size" do |im, io|
+    assert im.save(io)
+
+    FileUtils.rm im.root("small.jpg")
+    assert ! File.exist?(im.root("small.jpg"))
+
+    thumb_io = File.open(fixture("r8-crop.jpg"), "rb")
+
+    im.update_size :small, thumb_io
+    assert File.exist?(im.root("small.jpg"))
+
+    assert_equal "100x75", resolution(im.root("small.jpg"))
+  end
 end
 
 # resizing with extent

test/s3.rb

@@ -68,12 +68,14 @@ class Imagery
 
   test "saves all sizes to S3" do |im, io|
     im.save(io)
+    im.update_size(:small, io)
 
     cmds = Imagery::S3::Gateway.commands
 
     assert_equal [:store, "avatar/1001/original.jpg", "buck"], cmds.shift
     assert_equal [:store, "avatar/1001/small.jpg", "buck"], cmds.shift
     assert_equal [:store, "avatar/1001/medium.jpg", "buck"], cmds.shift
+    assert_equal [:store, "avatar/1001/small.jpg", "buck"], cmds.shift
 
     assert cmds.empty?
   end