FEATURE: new twitter_summary_large_image_url setting

app/helpers/application_helper.rb

@@ -142,8 +142,9 @@ module ApplicationHelper
     opts ||= {}
     opts[:url] ||= "#{Discourse.base_url_no_prefix}#{request.fullpath}"
 
-    if opts[:image].blank? && SiteSetting.default_opengraph_image_url.present?
+    if opts[:image].blank? && (SiteSetting.default_opengraph_image_url.present? || SiteSetting.twitter_summary_large_image_url.present?)
-      opts[:image] = SiteSetting.default_opengraph_image_url
+      opts[:twitter_summary_large_image] = SiteSetting.twitter_summary_large_image_url if SiteSetting.twitter_summary_large_image_url.present?
+      opts[:image] = SiteSetting.default_opengraph_image_url.present? ? SiteSetting.default_opengraph_image_url : SiteSetting.twitter_summary_large_image_url
     elsif opts[:image].blank? && SiteSetting.apple_touch_icon_url.present?
       opts[:image] = SiteSetting.apple_touch_icon_url
     end
@@ -156,12 +157,22 @@ module ApplicationHelper
       opts[:image] = "#{Discourse.base_url}#{opts[:image]}"
     end
 
-    # Add opengraph tags
+    # Add opengraph & twitter tags
     result = []
     result << tag(:meta, property: 'og:site_name', content: SiteSetting.title)
-    result << tag(:meta, name: 'twitter:card', content: "summary")
 
-    [:url, :title, :description, :image].each do |property|
+    if opts[:twitter_summary_large_image].present?
+      result << tag(:meta, name: 'twitter:card', content: "summary_large_image")
+      result << tag(:meta, name: "twitter:image", content: opts[:twitter_summary_large_image])
+    elsif opts[:image].present?
+      result << tag(:meta, name: 'twitter:card', content: "summary")
+      result << tag(:meta, name: "twitter:image", content: opts[:image])
+    else
+      result << tag(:meta, name: 'twitter:card', content: "summary")
+    end
+    result << tag(:meta, property: "og:image", content: opts[:image]) if opts[:image].present?
+
+    [:url, :title, :description].each do |property|
       if opts[property].present?
         escape = (property != :image)
         result << tag(:meta, { property: "og:#{property}", content: opts[property] }, nil, escape)

config/locales/server.en.yml

@@ -1086,6 +1086,7 @@ en:
     external_system_avatars_url: "URL of the external system avatars service. Allowed substitutions are {username} {first_letter} {color} {size}"
 
     default_opengraph_image_url: "URL of the default opengraph image."
+    twitter_summary_large_image_url: "URL of the default Twitter summary card image (should be at least 280px in width, and at least 150px in height)."
 
     allow_all_attachments_for_group_messages: "Allow all email attachments for group messages."
 

config/site_settings.yml

@@ -56,6 +56,7 @@ required:
     default: '/images/default-favicon.ico'
   apple_touch_icon_url: '/images/default-apple-touch-icon.png'
   default_opengraph_image_url: ''
+  twitter_summary_large_image_url: ''
   exclude_rel_nofollow_domains:
     default: ''
     type: list