/*
* TypeHelpers version 1.0
* Zoltan Hawryluk, Nov 24 2009.
* @see http://www.useragentman.com/blog/2009/11/29/how-to-detect-font-smoothing-using-javascript/
*
* Released under the MIT License. http://www.opensource.org/licenses/mit-license.php
*
* Works for
* - IE6+ (Windows),
* - Firefox 3.5+ (Windows, Mac, Linux),
* - Safari 4+ (Windows, Mac OS X),
* - Chrome 3.0+ (Windows).
* Opera 10.10 and under reports unknown support for font-smoothing.
*
* Modified by Christian Beier (www.beier-christian.eu) to detect the ClearType technology.
*
* Required: jQuery 1.3.x
*
*
* METHODS
* -------
*
* hasSmoothing() returns:
* true if font smoothing is enabled
* false if font smoothing isn't enabled
* null if it cannot detect if it's on or not.
*
* addClasses() adds the following classes to the html tag:
* "hasFontSmoothing-true" if font smoothing is enabled
* "hasFontSmoothing-false" if it isn't
* "hasFontSmoothing-unknown" if it cannot detect it.
*
*/

var TypeHelpers = new function() {
  var me = this;
  
  me.hasSmoothing = function(){
    // IE has screen.fontSmoothingEnabled - sweet!
    if (typeof(screen.fontSmoothingEnabled) != "undefined") {
      return screen.fontSmoothingEnabled;
    } else {
	  try {
        // Create a 35x35 Canvas block.
        var canvasNode = document.createElement("canvas");
        canvasNode.width = "35";
        canvasNode.height = "35"
        
        // We must put this node into the body, otherwise
        // Safari Windows does not report correctly.
        canvasNode.style.display = "none";
        document.body.appendChild(canvasNode);
        var ctx = canvasNode.getContext("2d");
        
        // draw a black letter "O", 32px Arial.
        ctx.textBaseline = "top";
        ctx.font = "32px Arial";
        ctx.fillStyle = "black";
        ctx.strokeStyle = "black";
        
        ctx.fillText("O", 0, 0);
        
        // start at (8,1) and search the canvas from left to right,
        // top to bottom to see if we can find a non-black pixel. If
        // so we return true.
        for (var j = 8; j <= 32; j++) {
          for (var i = 1; i <= 32; i++) {
            var imageData = ctx.getImageData(i, j, 1, 1).data
            var alpha = imageData[3];
                                    
            if (alpha != 255 && alpha != 0 && alpha > 180) {
              return true; // font-smoothing must be on.
              }
            }
          }
         
          // didn't find any non-black pixels - return false.
          return false;
        }
        catch (ex) {
          // Something went wrong (for example, Opera cannot use the
          // canvas fillText() method. Return null (unknown).
          return null;
        }
      }
    }
   
  $(document).ready(function() {
    var result = me.hasSmoothing();
    if (result == true) {
      $('html').addClass('hasFontSmoothing-true');
    } else if (result == false) {
      $('html').addClass('hasFontSmoothing-false');
    } else { // result == null
      $('html').addClass('hasFontSmoothing-unknown');
    }
  });
}