+
+/*
+ * Called to interpolate JavaScript variables in strings using a
+ * similar syntax to rails I18n string interpolation - the only
+ * difference is that [[foo]] is the placeholder syntax instead
+ * of {{foo}} which allows the same string to be processed by both
+ * rails and then later by javascript.
+ */
+function i18n(string, keys) {
+ string = i18n_strings[string] || string
+
+ for (var key in keys) {
+ var re_key = '\\[\\[' + key + '\\]\\]';
+ var re = new RegExp(re_key, "g");
+
+ string = string.replace(re, keys[key]);
+ }
+
+ return string;
+}
+
+/*
+ * Called to interlace the bits in x and y, making a Morton code.
+ */
+function interlace(x, y) {
+ x = (x | (x << 8)) & 0x00ff00ff;
+ x = (x | (x << 4)) & 0x0f0f0f0f;
+ x = (x | (x << 2)) & 0x33333333;
+ x = (x | (x << 1)) & 0x55555555;
+
+ y = (y | (y << 8)) & 0x00ff00ff;
+ y = (y | (y << 4)) & 0x0f0f0f0f;
+ y = (y | (y << 2)) & 0x33333333;
+ y = (y | (y << 1)) & 0x55555555;
+
+ return (x << 1) | y;
+}
+
+/*
+ * Called to create a short code for the short link.
+ */
+function makeShortCode(lat, lon, zoom) {
+ char_array = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789_@";
+ var x = Math.round((lon + 180.0) * ((1 << 30) / 90.0));
+ var y = Math.round((lat + 90.0) * ((1 << 30) / 45.0));
+ // JavaScript only has to keep 32 bits of bitwise operators, so this has to be
+ // done in two parts. each of the parts c1/c2 has 30 bits of the total in it
+ // and drops the last 4 bits of the full 64 bit Morton code.
+ var str = "";
+ var c1 = interlace(x >>> 17, y >>> 17), c2 = interlace((x >>> 2) & 0x7fff, (y >>> 2) & 0x7fff);
+ for (var i = 0; i < Math.ceil((zoom + 8) / 3.0) && i < 5; ++i) {
+ digit = (c1 >> (24 - 6 * i)) & 0x3f;
+ str += char_array.charAt(digit);
+ }
+ for (var i = 5; i < Math.ceil((zoom + 8) / 3.0); ++i) {
+ digit = (c2 >> (24 - 6 * (i - 5))) & 0x3f;
+ str += char_array.charAt(digit);
+ }
+ for (var i = 0; i < ((zoom + 8) % 3); ++i) {
+ str += "-";
+ }
+ return str;
+}