Merge pull request #53 from mejackreed/twitter-cart

add twitter card md

examples/index.js

@@ -1,16 +1,25 @@
 var map;
+var layer;
 
 map = L.map('map', {
   center: [0, 0],
   crs: L.CRS.Simple,
   zoom: 0
 });
 
-var url = window.location.search.replace('?url=', '')
+var url = window.location.search.replace('?url=', '');
 
 // http://stackoverflow.com/a/18222306
 var urlregex = /^(ftp|http|https):\/\/(\w+:{0,1}\w*@)?(\S+)(:[0-9]+)?(\/|\/([\w#!:.?+=&%@!\-\/]))?$/;
 
 if (urlregex.test(url)) {
   layer = L.tileLayer.iiif(url, {}).addTo(map);
 }
+
+layer.on('load', function() {
+  $('head').append(
+    '<meta name="twitter:card" content="summary_large_image">' +
+    '<meta name="twitter:site" content="@mejackreed">' +
+    '<meta name="twitter:image" content="' + url.replace('info.json', 'full/' + layer._imageSizes[1].x + ',/0/default.jpg') + '">'
+  );
+});