ldr favicon hack

ldr_favicon_hack.user.js

// ==UserScript==
// @name           ldr favicon hack
// @namespace      http://d.hatena.ne.jp/javascripter/
// @include        http://reader.livedoor.com/reader/
// @include        http://fastladder.com/reader/
// ==/UserScript==
(function() {
  unsafeWindow.document.watch('title',
  function(id, before, after) {
    updateFavicon();
    return after
  });
  var favicon = document.evaluate('//head/link[@rel="shortcut icon"]', document, null, XPathResult.FIRST_ORDERED_NODE_TYPE, null).singleNodeValue;
  var canvas = document.createElement('canvas');
  var head = document.getElementsByTagName('head')[0];

  function updateFavicon() {
    var unread = unsafeWindow.subs.model.get_unread_count();
    var img = new Image();
    img.src = '/favicon.ico';
    canvas.width = canvas.height = 16;
    if (999 < unread) unread = "1k+";
    with(canvas.getContext('2d')) {
      drawImage(img, 0, 0, 16, 8);
      mozTextStyle = 22 + (unread.toString().length) * -4 + "px monospace";
      translate(0, 16);
      fillStyle = "blue";
      mozDrawText(unread);
    }
    favicon.href = canvas.toDataURL();
    head.appendChild(favicon);
  }
})();