Merge pull request #100 from mojavelinux/find-bg-image

find the background image block in a portable and reliable way

templates/slim/section.html.slim

@@ -13,19 +13,20 @@
 - data_background_image, data_background_size, data_background_repeat,
   data_background_transition = nil
 
-/ find all images under current node with attribute background or canvas
-/ as long as they are of the same level as we are currently processing
-- slide_images = find_by(:context => :image) { |image|
--   (image.attr(1) == 'background' || image.attr(1) == 'canvas') && image.level == level
-- }
-- unless slide_images.nil? or slide_images.length == 0
-  - slide_images.each do |image|
-    - data_background_image = image_uri(image.attr 'target')
-    / make sure no crash on nil and default values make sense
-    - data_background_size = image.attr 'size'
-    - data_background_repeat = image.attr 'repeat'
-    - data_background_transition = image.attr 'transition'
-    - break
+/ process the first image block in the current section that acts as a background
+- section_images = blocks.map do |block|
+  - if (ctx = block.context) == :image
+    - ['background', 'canvas'].include?(block.attr 1) ? block : []
+  - elsif ctx == :section
+    - []
+  - else
+    - block.find_by(context: :image) {|image| ['background', 'canvas'].include?(image.attr 1) } || []
+- if (bg_image = section_images.flatten.first)
+  - data_background_image = image_uri(bg_image.attr 'target')
+  / make sure no crash on nil and default values make sense
+  - data_background_size = bg_image.attr 'size'
+  - data_background_repeat = bg_image.attr 'repeat'
+  - data_background_transition = bg_image.attr 'transition'
 
 / background-image section attribute overrides the image one
 - if attr? 'background-image'