plugins/LinkPreview/linkpreview.js

   1 /**
   2  * (c) 2010 StatusNet, Inc.
   3  */
   4
   5 (function() {
   6     var oEmbed = {
   7         api: 'http://oohembed.com/oohembed',
   8         width: 100,
   9         height: 75,
  10         cache: {},
  11         callbacks: {},
  12
  13         /**
  14          * Do a cached oEmbed lookup for the given URL.
  15          *
  16          * @param {String} url
  17          * @param {function} callback
  18          */
  19         lookup: function(url, callback)
  20         {
  21             if (typeof oEmbed.cache[url] == "object") {
  22                 // We already have a successful lookup.
  23                 callback(oEmbed.cache[url]);
  24             } else if (typeof oEmbed.callbacks[url] == "undefined") {
  25                 // No lookup yet... Start it!
  26                 oEmbed.callbacks[url] = [callback];
  27
  28                 oEmbed.rawLookup(url, function(data) {
  29                     oEmbed.cache[url] = data;
  30                     var callbacks = oEmbed.callbacks[url];
  31                     oEmbed.callbacks[url] = undefined;
  32                     for (var i = 0; i < callbacks.length; i++) {
  33                         callbacks[i](data);
  34                     }
  35                 });
  36             } else {
  37                 // A lookup is in progress.
  38                 oEmbed.callbacks[url].push(callback);
  39             }
  40         },
  41
  42         /**
  43          * Do an oEmbed lookup for the given URL.
  44          *
  45          * @fixme proxy through ourselves if possible?
  46          * @fixme use the global thumbnail size settings
  47          *
  48          * @param {String} url
  49          * @param {function} callback
  50          */
  51         rawLookup: function(url, callback)
  52         {
  53             var params = {
  54                 url: url,
  55                 format: 'json',
  56                 maxwidth: oEmbed.width,
  57                 maxheight: oEmbed.height
  58             };
  59             $.get(oEmbed.api, params, function(data, xhr) {
  60                 callback(data);
  61             }, 'json');
  62         }
  63     };
  64
  65     var LinkPreview = {
  66         links: [],
  67
  68         /**
  69          * Find URL links from the source text that may be interesting.
  70          *
  71          * @param {String} text
  72          * @return {Array} list of URLs
  73          */
  74         findLinks: function (text)
  75         {
  76             // @fixme match this to core code
  77             var re = /(?:^| )(https?:\/\/.+?\/.+?)(?= |$)/mg;
  78             var links = [];
  79             var matches;
  80             while ((matches = re.exec(text)) !== null) {
  81                 links.push(matches[1]);
  82             }
  83             return links;
  84         },
  85
  86         /**
  87          * Start looking up info for a link preview...
  88          * May start async data loads.
  89          *
  90          * @param {String} id
  91          * @param {String} url
  92          */
  93         prepLinkPreview: function(id, url)
  94         {
  95             oEmbed.lookup(url, function(data) {
  96                 var thumb = null;
  97                 var width = 100;
  98                 if (typeof data.thumbnail_url == "string") {
  99                     thumb = data.thumbnail_url;
 100                     if (typeof data.thumbnail_width !== "undefined") {
 101                         if (data.thumbnail_width < width) {
 102                             width = data.thumbnail_width;
 103                         }
 104                     }
 105                 } else if (data.type == 'photo' && typeof data.url == "string") {
 106                     thumb = data.url;
 107                     if (typeof data.width !== "undefined") {
 108                         if (data.width < width) {
 109                             width = data.width;
 110                         }
 111                     }
 112                 }
 113                 if (thumb) {
 114                     var link = $('<span class="inline-attachment"><a><img/></a></span>');
 115                     link.find('a')
 116                             .attr('href', url)
 117                             .attr('target', '_blank')
 118                             .last()
 119                         .find('img')
 120                             .attr('src', thumb)
 121                             .attr('width', width)
 122                             .attr('title', data.title || data.url || url);
 123                     $('#' + id).append(link);
 124                 }
 125             });
 126         },
 127
 128         /**
 129          * Update the live preview section with links found in the given text.
 130          * May start async data loads.
 131          *
 132          * @param {String} text: free-form input text
 133          */
 134         previewLinks: function(text)
 135         {
 136             var old = LinkPreview.links;
 137             var links = LinkPreview.findLinks(text);
 138
 139             // Check for existing common elements...
 140             for (var i = 0; i < old.length && i < links.length; i++) {
 141                 if (links[i] != old[i]) {
 142                     // Change an existing entry!
 143                     var id = 'link-preview-' + i;
 144                     $('#' + id).html('');
 145                     LinkPreview.prepLinkPreview(id, links[i]);
 146                 }
 147             }
 148             if (links.length > old.length) {
 149                 // Adding new entries, whee!
 150                 for (var i = old.length; i < links.length; i++) {
 151                     var id = 'link-preview-' + i;
 152                     $('#link-preview').append('<span id="' + id + '"></span>');
 153                     LinkPreview.prepLinkPreview(id, links[i]);
 154                 }
 155             } else if (old.length > links.length) {
 156                 // Remove preview entries for links that have been removed.
 157                 for (var i = links.length; i < old.length; i++) {
 158                     var id = 'link-preview-' + i;
 159                     $('#' + id).remove();
 160                 }
 161             }
 162
 163             LinkPreview.links = links;
 164         },
 165
 166         /**
 167          * Clear out any link preview data.
 168          */
 169         clear: function() {
 170             LinkPreview.links = [];
 171             $('#link-preview').empty();
 172         }
 173     };
 174
 175     SN.Init.LinkPreview = function(params) {
 176         if (params.api) oEmbed.api = params.api;
 177         if (params.width) oEmbed.width = params.width;
 178         if (params.height) oEmbed.height = params.height;
 179
 180         $('#form_notice')
 181             .append('<div id="link-preview" class="thumbnails"></div>')
 182             .bind('reset', function() {
 183                 LinkPreview.clear();
 184             });
 185
 186         // Piggyback on the counter update...
 187         var origCounter = SN.U.Counter;
 188         SN.U.Counter = function(form) {
 189             LinkPreview.previewLinks($('#notice_data-text').val());
 190             return origCounter(form);
 191         }
 192     }
 193 })();