fix github network graph for chrome retina

onload-network-graph-fix.js

/*
MIT: https://raw.github.com/github/hubot/1455b62e5b6daffeacb7472db83ccf6502396bea/LICENSE.md

refs:
http://developer.apple.com/library/safari/documentation/AudioVideo/Conceptual/HTML-canvas-guide/SettingUptheCanvas/SettingUptheCanvas.html
http://www.html5rocks.com/en/tutorials/canvas/hidpi/
https://code.google.com/p/chromium/issues/detail?id=127852 (WONTFIX)
*/

(function(doc) {
  var can = $("#ng canvas")[0];
  if (!can) { return false; }
  var canOW = can.width,
      canOH = can.height,
      context = can.getContext("2d");

  var devicePixelRatio = window.devicePixelRatio || 1;
  
  // in case chromium aren't the only team ignoring pragmatism.
  var backingStoreRatio = context.webkitBackingStorePixelRatio ||
                          context.mozBackingStorePixelRatio ||
                          context.msBackingStorePixelRatio ||
                          context.oBackingStorePixelRatio ||
                          context.backingStorePixelRatio || 1;

  var ratio = devicePixelRatio / backingStoreRatio;

  if (ratio === 1) { return; }

  can.width = canOW*ratio;
  can.height = canOH*ratio;
  can.style.width = canOW+'px';
  can.style.height = canOH+'px';
  context.scale(ratio, ratio);
}(document));