/*
 * Hover PNG by OKFocus - http://okfoc.us - @okfocus
 * Version 1.0
 * Licensed under MIT.
 *
 */

(function($){

  $.hoverpng = function(el, options){
    var base = this;       
    base.$el = $(el);
    base.el = el;        
    base.$el.data("hoverpng", base);
    
    var active = true, hovering = false;
    var canvas, imageData = null;

    base.init = function(){            
      base.options = $.extend({}, $.hoverpng.options, options);
      base.options.threshold = Math.floor( base.options.threshold *= 254 );
      base.build();
    };
    
    base.build = function(){
    	$(window).bind({
				'blur': function(){ hovering = false; }
    	});
      base.$el.bind({
        'load': base.fetch,
        'mouseover': base.mouseover,
        'mouseout': base.mouseout,
        'mousemove': base.mousemove
      });
      if (base.el.complete) {
        base.fetch();
      }
    };

    base.fetch = function(){
      canvas = document.createElement("canvas");
      canvas.width = base.el.naturalWidth;
      canvas.height = base.el.naturalHeight;
      var ctx = canvas.getContext('2d');
      ctx.drawImage(base.el, 0, 0);
      imageData = ctx.getImageData( 0, 0, canvas.width, canvas.height ).data;
    }
    
    base.clamp = function (x, min, max) {
      return Math.max(min, Math.min(max, x));
    };

    base.mouseover = function(e) {
      if ( base.detect(e) ) {
        hovering = true;
        base.options.mouseover(e);
      }
    }
    base.mouseout = function(e) {
      if ( hovering ) {
        base.options.mouseout(e);
      }
      hovering = false;
    }
    base.mousemove = function(e) {
      if ( base.detect(e) ) {
        if ( hovering ) {
xxx = e;
          base.options.mousemove(e);
        }
        else {
          base.options.mouseover(e);
        }
        hovering = true;
      }
      else if ( hovering ) {
        base.options.mouseout(e);
        hovering = false;
      }
    }
    base.detect = function (e){
      if (! imageData) {
        return false;
      }
      var offset = base.$el.offset();
      var x = e.pageX - offset.left;
      var y = e.pageY - offset.top;
      var pixelOffset = (canvas.width * y + x) * 4;
      var alpha = imageData[ pixelOffset + 3 ];
      e.rgba = [
        imageData[(canvas.width * y + x) * 4 ],
        imageData[(canvas.width * y + x) * 4 + 1 ],
        imageData[(canvas.width * y + x) * 4 + 2 ],
        imageData[(canvas.width * y + x) * 4 + 3 ]
      ];
      e.alpha = alpha;
      return alpha > base.options.threshold;
    }

    base.init();
  };

  $.hoverpng.options = { 
    mouseover: function(){},
    mousemove: function(){},
    mouseout: function(){},
    threshold: 0
  };
  
  $.fn.hoverpng = function(options){
    return this.each(function(){
      (new $.hoverpng(this, options));            
    });
  };
  
  function detectMobile () {
    return navigator.userAgent.indexOf("Mobile") !== -1 || navigator.userAgent.indexOf("Android") !== -1;
  }
})(jQuery);