[devdocsgjs/main: 704/1867] Fix favicon on HiDPI displays

[Andy Holmes <andyholmes src gnome org>]

commit c01982ca9add42352d8ffe1f9b83579d4fdd7892
Author: Jasper van Merle <jaspervmerle gmail com>
Date:   Sun Aug 4 12:51:19 2019 +0200

    Fix favicon on HiDPI displays

 assets/javascripts/app/config.coffee.erb | 1 +
 assets/javascripts/lib/favicon.coffee    | 4 ++--
 2 files changed, 3 insertions(+), 2 deletions(-)
---
diff --git a/assets/javascripts/app/config.coffee.erb b/assets/javascripts/app/config.coffee.erb
index dba368e0..a822f7e2 100644
--- a/assets/javascripts/app/config.coffee.erb
+++ b/assets/javascripts/app/config.coffee.erb
@@ -13,5 +13,6 @@ app.config =
   version: <%= Time.now.to_i %>
   release: <%= Time.now.utc.httpdate.to_json %>
   mathml_stylesheet: '<%= App.cdn_origin %>/mathml.css'
+  favicon_spritesheet: '<%= image_path('sprites/docs.png') %>'
   service_worker_path: '/service-worker.js'
   service_worker_enabled: <%= App.environment == :production || ENV['ENABLE_SERVICE_WORKER'] == 'true' %>
diff --git a/assets/javascripts/lib/favicon.coffee b/assets/javascripts/lib/favicon.coffee
index 5254b54c..2f2d9f93 100644
--- a/assets/javascripts/lib/favicon.coffee
+++ b/assets/javascripts/lib/favicon.coffee
@@ -30,8 +30,8 @@ withImage = (url, action) ->
 
   styles = window.getComputedStyle($("._icon-#{doc.slug.split('~')[0]}"), ':before')
 
-  bgUrl = styles['background-image'].slice(5, -2)
-  sourceSize = if bgUrl.includes('@2x') then 32 else 16
+  bgUrl = app.config.favicon_spritesheet
+  sourceSize = 16
   sourceX = Math.abs(parseInt(styles['background-position-x'].slice(0, -2)))
   sourceY = Math.abs(parseInt(styles['background-position-y'].slice(0, -2)))