Load Tegaki from rawgit.com if loading from s.4cdn.org fails or is blocked.

src/Posting/QR.oekaki.coffee

@@ -55,23 +55,39 @@ QR.oekaki =
             bubbles: true
             detail: {file, name: FCX.oekakiName, source}
           }
-      if window.Tegaki
-        document.querySelector('#qr .oekaki').hidden = false
+    if $ 'link[href^="//s.4cdn.org/css/painter"]', d.head
+      QR.oekaki.load ->
+        $('#qr .oekaki').hidden = false
 
   load: (cb) ->
-    if $ 'script[src^="//s.4cdn.org/js/painter"]', d.head
-      cb()
+    n = 0
+    onload = ->
+      cb() if ++n is 2
+    onerror = ->
+      $.rm @
+      script = $.el 'script',
+        src: 'https://rawgit.com/desuwa/tegaki/master/tegaki.js'
+      $.on script, 'load', onload
+      $.add d.head, script
+    script = $ 'script[src^="//s.4cdn.org/js/painter"], script[src="https://rawgit.com/desuwa/tegaki/master/tegaki.js"]', d.head
+    if script
+      if !script.dataset.success
+        $.global ->
+          document.querySelector('script[src^="//s.4cdn.org/js/painter"], script[src="https://rawgit.com/desuwa/tegaki/master/tegaki.js"]').dataset.success = !!window.Tegaki
+      if script.dataset.success is 'true'
+        cb()
+      else
+        n = 1
+        onerror.call script
     else
       style = $.el 'link',
         rel: 'stylesheet'
         href: "//s.4cdn.org/css/painter.#{Date.now()}.css"
       script = $.el 'script',
         src: "//s.4cdn.org/js/painter.min.#{Date.now()}.js"
-      n = 0
-      onload = ->
-        cb() if ++n is 2
       $.on style,  'load', onload
       $.on script, 'load', onload
+      $.on script, 'error', onerror
       $.add d.head, [style, script]
 
   draw: ->

src/config/Config.coffee

@@ -832,6 +832,7 @@ Config =
     http://cdn.mathjax.org
     https://cdn.mathjax.org
     https://cdnjs.cloudflare.com
+    https://rawgit.com
     'self'
     'unsafe-inline'
     'unsafe-eval'