FEATURE: SVG letter avatars (based on @eviltrout's spike)

app/assets/javascripts/discourse/lib/avatar-template.js.es6

@@ -4,6 +4,7 @@ let _splitAvatars;
 
 function defaultAvatar(username) {
   const defaultAvatars = Discourse.SiteSettings.default_avatars;
+
   if (defaultAvatars && defaultAvatars.length) {
     _splitAvatars = _splitAvatars || defaultAvatars.split("\n");
 
@@ -13,20 +14,13 @@ function defaultAvatar(username) {
     }
   }
 
-  return Discourse.getURLWithCDN("/letter_avatar/" +
+  const extension = Discourse.SiteSettings.svg_letter_avatars ? "svg" : "png";
-                                 username.toLowerCase() +
+  return Discourse.getURLWithCDN(`/letter_avatar/${username.toLowerCase()}/{size}/${Discourse.LetterAvatarVersion}.${extension}`);
-                                 "/{size}/" +
-                                 Discourse.LetterAvatarVersion + ".png");
 }
 
 export default function(username, uploadedAvatarId) {
   if (uploadedAvatarId) {
-    return Discourse.getURLWithCDN("/user_avatar/" +
+    return Discourse.getURLWithCDN(`/user_avatar/${Discourse.BaseUrl}/${username.toLowerCase()}/{size}/${uploadedAvatarId}.png`);
-                                   Discourse.BaseUrl +
-                                   "/" +
-                                   username.toLowerCase() +
-                                   "/{size}/" +
-                                   uploadedAvatarId + ".png");
   }
   return defaultAvatar(username);
 }

app/controllers/user_avatars_controller.rb

@@ -3,7 +3,7 @@ require_dependency 'letter_avatar'
 class UserAvatarsController < ApplicationController
   DOT = Base64.decode64("R0lGODlhAQABALMAAAAAAIAAAACAAICAAAAAgIAAgACAgMDAwICAgP8AAAD/AP//AAAA//8A/wD//wBiZCH5BAEAAA8ALAAAAAABAAEAAAQC8EUAOw==")
 
-  skip_before_filter :preload_json, :redirect_to_login_if_required, :check_xhr, :verify_authenticity_token, only: [:show, :show_letter]
+  skip_before_filter :preload_json, :redirect_to_login_if_required, :check_xhr, :verify_authenticity_token, only: [:show, :show_letter, :show_letter_svg]
 
   def refresh_gravatar
     user = User.find_by(username_lower: params[:username].downcase)
@@ -19,6 +19,30 @@ class UserAvatarsController < ApplicationController
     end
   end
 
+  def show_letter_svg
+    params.require(:username)
+    params.require(:version)
+    params.require(:size)
+
+    no_cookies
+
+    size = params[:size].to_i
+    username = params[:username]
+
+    identity = LetterAvatar::Identity.from_username(username)
+    color = identity.color
+
+    svg = <<-SVG
+      <svg xmlns="http://www.w3.org/2000/svg" width="#{size}" height="#{size}">
+        <rect width="100%" height="100%" fill="rgb(#{color[0]},#{color[1]},#{color[2]})" />
+        <text font-size="#{size * 0.7}" font-weight="normal" font-family="Helvetica, sans-serif" fill="#FFF" fill-opacity=".8" text-anchor="middle" x="50%" y="75%">#{username[0].capitalize}</text>
+      </svg>
+    SVG
+
+    expires_in 1.year, public: true
+    render inline: svg, content_type: "image/svg+xml"
+  end
+
   def show_letter
     params.require(:username)
     params.require(:version)

app/models/user.rb

@@ -457,7 +457,7 @@ class User < ActiveRecord::Base
         avatar_template = split_avatars[hash.abs % split_avatars.size]
       end
     else
-      "#{Discourse.base_uri}/letter_avatar/#{username.downcase}/{size}/#{LetterAvatar.version}.png"
+      letter_avatar_template(username)
     end
   end
 
@@ -469,7 +469,8 @@ class User < ActiveRecord::Base
   end
 
   def self.letter_avatar_template(username)
-    "#{Discourse.base_uri}/letter_avatar/#{username.downcase}/{size}/#{LetterAvatar.version}.png"
+    extension = SiteSetting.svg_letter_avatars ? "svg" : "png"
+    "#{Discourse.base_uri}/letter_avatar/#{username.downcase}/{size}/#{LetterAvatar.version}.#{extension}"
   end
 
   def avatar_template

config/locales/server.en.yml

@@ -979,6 +979,8 @@ en:
 
     avatar_sizes: "List of automatically generated avatar sizes."
 
+    svg_letter_avatars: "Use SVG for letter avatars"
+
     enable_flash_video_onebox: "Enable embedding of swf and flv (Adobe Flash) links in oneboxes. WARNING: may introduce security risks."
 
     default_invitee_trust_level: "Default trust level (0-4) for invited users."

config/routes.rb

@@ -299,6 +299,7 @@ Discourse::Application.routes.draw do
   get "user-badges/:username" => "user_badges#username", constraints: {username: USERNAME_ROUTE_FORMAT}
 
   post "user_avatar/:username/refresh_gravatar" => "user_avatars#refresh_gravatar", constraints: {username: USERNAME_ROUTE_FORMAT}
+  get "letter_avatar/:username/:size/:version.svg" => "user_avatars#show_letter_svg", format: :svg, constraints: { hostname: /[\w\.-]+/, size: /\d+/, username: USERNAME_ROUTE_FORMAT}
   get "letter_avatar/:username/:size/:version.png" => "user_avatars#show_letter", format: false, constraints: { hostname: /[\w\.-]+/, size: /\d+/, username: USERNAME_ROUTE_FORMAT}
   get "user_avatar/:hostname/:username/:size/:version.png" => "user_avatars#show", format: false, constraints: { hostname: /[\w\.-]+/, size: /\d+/, username: USERNAME_ROUTE_FORMAT }
 

config/site_settings.yml

@@ -572,6 +572,9 @@ files:
   avatar_sizes:
     default: '20|25|32|45|60|120'
     type: list
+  svg_letter_avatars:
+    default: false
+    client: true
 
 trust:
   default_trust_level:

lib/email/styles.rb

@@ -30,7 +30,6 @@ module Email
 
       # images
       @fragment.css('img').each do |img|
-
         next if img['class'] == 'site-logo'
 
         if img['class'] == "emoji" || img['src'] =~ /plugins\/emoji/
@@ -58,7 +57,6 @@ module Email
 
       # attachments
       @fragment.css('a.attachment').each do |a|
-
         # ensure all urls are absolute
         if a['href'] =~ /^\/[^\/]/
           a['href'] = "#{Discourse.base_url}#{a['href']}"

lib/letter_avatar.rb

@@ -7,8 +7,6 @@ class LetterAvatar
   FULLSIZE  = 120 * 3
   POINTSIZE = 280
 
-  class << self
-
   class Identity
     attr_accessor :color, :letter
 
@@ -22,6 +20,8 @@ class LetterAvatar
     end
   end
 
+  class << self
+
     def version
       "#{VERSION}_#{image_magick_version}"
     end
@@ -32,7 +32,7 @@ class LetterAvatar
 
     def generate(username, size, opts = nil)
       DistributedMutex.synchronize("letter_avatar_#{version}_#{username}") do
-        identity = Identity.from_username(username)
+        identity = LetterAvatar::Identity.from_username(username)
 
         cache = true
         cache = false if opts && opts[:cache] == false