post replacement: rescale notes.

app/models/note.rb

@@ -127,6 +127,14 @@ class Note < ActiveRecord::Base
     User.id_to_name(creator_id)
   end
 
+  def rescale!(x_scale, y_scale)
+    self.x *= x_scale
+    self.y *= y_scale
+    self.width *= x_scale
+    self.height *= y_scale
+    save!
+  end
+
   def update_post
     if self.changed?
       if Note.where(:is_active => true, :post_id => post_id).exists?

app/models/post_replacement.rb

@@ -17,11 +17,6 @@ class PostReplacement < ActiveRecord::Base
   end
 
   def process!
-    # TODO for posts with notes we need to rescale the notes if the dimensions change.
-    if post.notes.any?
-      raise NotImplementedError.new("Replacing images with notes not yet supported.")
-    end
-
     # TODO for ugoiras we need to replace the frame data.
     if post.is_ugoira?
       raise NotImplementedError.new("Replacing ugoira images not yet supported.")
@@ -49,6 +44,7 @@ class PostReplacement < ActiveRecord::Base
       post.file_size = upload.file_size
       post.source = upload.source
       post.tag_string = upload.tag_string
+      rescale_notes
 
       post.comments.create!({creator: User.system, body: comment_replacement_message, do_not_bump_post: true}, without_protection: true)
       ModAction.log(modaction_replacement_message)
@@ -62,6 +58,15 @@ class PostReplacement < ActiveRecord::Base
     post.update_iqdb_async
   end
 
+  def rescale_notes
+    x_scale = post.image_width.to_f  / post.image_width_was.to_f
+    y_scale = post.image_height.to_f / post.image_height_was.to_f
+
+    post.notes.each do |note|
+      note.rescale!(x_scale, y_scale)
+    end
+  end
+
   module SearchMethods
     def search(params = {})
       q = all

test/unit/post_replacement_test.rb

@@ -102,6 +102,27 @@ class PostReplacementTest < ActiveSupport::TestCase
       end
     end
 
+    context "a post with notes" do
+      setup do
+        @post.update({image_width: 160, image_height: 164}, without_protection: true)
+        CurrentUser.scoped(@uploader, "127.0.0.1") do
+          @note = @post.notes.create(x: 80, y: 82, width: 80, height: 82, body: "test")
+        end
+      end
+
+      should "rescale the notes" do
+        assert_equal([80, 82, 80, 82], [@note.x, @note.y, @note.width, @note.height])
+
+        assert_difference("@replacer.note_versions.count") do
+          # replacement image is 80x82, so we're downscaling by 50% (160x164 -> 80x82).
+          @post.replace!(replacement_url: "https://www.pixiv.net/member_illust.php?mode=medium&illust_id=62247350")
+          @note.reload
+        end
+
+        assert_equal([40, 41, 40, 41], [@note.x, @note.y, @note.width, @note.height])
+      end
+    end
+
     context "a post with a pixiv html source" do
       should "replace with the full size image" do
         @post.replace!(replacement_url: "https://www.pixiv.net/member_illust.php?mode=medium&illust_id=62247350")