From 52b8a0db689c2df968776a1f369ea6a6db245d39 Mon Sep 17 00:00:00 2001
From: Tim Zallmann <tzallmann@gitlab.com>
Date: Mon, 24 Jul 2017 17:36:52 +0000
Subject: Resolve "Lazy load images on the Frontend"

---
 app/helpers/lazy_image_tag_helper.rb | 24 ++++++++++++++++++++++++
 1 file changed, 24 insertions(+)
 create mode 100644 app/helpers/lazy_image_tag_helper.rb

(limited to 'app/helpers/lazy_image_tag_helper.rb')

diff --git a/app/helpers/lazy_image_tag_helper.rb b/app/helpers/lazy_image_tag_helper.rb
new file mode 100644
index 00000000000..2c5619ac41b
--- /dev/null
+++ b/app/helpers/lazy_image_tag_helper.rb
@@ -0,0 +1,24 @@
+module LazyImageTagHelper
+  def placeholder_image
+    "data:image/gif;base64,R0lGODlhAQABAAAAACH5BAEKAAEALAAAAAABAAEAAAICTAEAOw=="
+  end
+
+  # Override the default ActionView `image_tag` helper to support lazy-loading
+  def image_tag(source, options = {})
+    options = options.symbolize_keys
+
+    unless options.delete(:lazy) == false
+      options[:data] ||= {}
+      options[:data][:src] = path_to_image(source)
+      options[:class] ||= ""
+      options[:class] << " lazy"
+
+      source = placeholder_image
+    end
+
+    super(source, options)
+  end
+
+  # Required for Banzai::Filter::ImageLazyLoadFilter
+  module_function :placeholder_image
+end
-- 
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