allow for using SVG logos in the navbar

this uses our ✨new and improved✨ logo by default, but can be easily
changed by modifying `/public/logo.svg`.  the svg is loaded only once
when the application starts, so any modifications to it after a
deployment are visible immediately.

thanks to the power of CSS and SVG being able to make use of it, custom
colour schemes still work too.

app/javascript/styles/overrides/_navbar.scss

@@ -6,6 +6,14 @@
     &:focus {
       color: RGB(var(--primary-text));
     }
+
+    /* svg-logo! \o/ */
+    svg {
+      height: $navbar-brand-font-size;
+      path {
+        fill: RGB(var(--primary-text));
+      }
+    }
   }
 
   .navbar-nav {

app/views/navigation/_desktop.haml

@@ -1,7 +1,10 @@
 %nav.navbar.navbar-themed.navbar-expand-lg.bg-primary.fixed-top.d-lg-block.d-none.d-print-none{ role: :navigation }
   .container{ class: ios_web_app? ? 'ios-web-app' : '' }
-    %a.navbar-brand{ href: '/' }
+    %a.navbar-brand{ href: '/', title: APP_CONFIG["site_name"] }
-      = APP_CONFIG['site_name']
+      - if APP_CONFIG["use_svg_logo"]
+        = render inline: Rails.application.config.justask_svg_logo
+      - else
+        = APP_CONFIG["site_name"]
     %ul.nav.navbar-nav.mr-auto
       = nav_entry t("navigation.timeline"), root_path, icon: 'home'
       = nav_entry t("navigation.inbox"), '/inbox', icon: 'inbox', badge: inbox_count

app/views/navigation/_guest.haml

@@ -1,6 +1,10 @@
 %nav.navbar.navbar-themed.navbar-expand-lg.bg-primary.fixed-top{ role: :navigation }
   .container{ class: ios_web_app? ? 'ios-web-app' : '' }
-    %a.navbar-brand{ href: '/' }= APP_CONFIG['site_name']
+    %a.navbar-brand{ href: '/', title: APP_CONFIG["site_name"] }
+      - if APP_CONFIG["use_svg_logo"]
+        = render inline: Rails.application.config.justask_svg_logo
+      - else
+        = APP_CONFIG["site_name"]
     %button.navbar-toggler{ data: { target: '#j2-main-navbar-collapse', toggle: :collapse }, type: :button }
       %span.sr-only= t("navigation.toggle")
       %span.navbar-toggler-icon

config/initializers/svg_logo.rb

@@ -0,0 +1,20 @@
+# frozen_string_literal: true
+
+return unless APP_CONFIG[:use_svg_logo]
+
+begin
+  logo_path = Rails.public_path.join("logo.svg")
+  # we are only interested in the first element which should be the <svg> node --> extract it and transform some attributes
+  logo_svg = File.read(logo_path)
+  svg_doc = Nokogiri::XML(logo_svg)
+  svg_node = svg_doc.first_element_child
+  # remove some attributes that might interfere with the rest of the layout
+  %w[id name class width height].each do |attr|
+    svg_node.remove_attribute attr
+  end
+
+  Rails.application.config.justask_svg_logo = svg_node.to_xml
+rescue => e
+  warn "use_svg_logo is enabled, but the SVG could not be read due to: #{e.message} (#{e.class.name}).  Disabling SVG logo."
+  APP_CONFIG[:use_svg_logo] = false
+end

config/justask.yml.example

@@ -1,6 +1,9 @@
 # The site name, shown everywhere.
 site_name: "justask"
 
+# Use the SVG logo from `/public/logo.svg`
+use_svg_logo: false
+
 hostname: "justask.rrerr.net"
 https: true
 

public/logo.svg

@@ -0,0 +1 @@
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