var lainCanvas = new Class({
	/* blurCompensation: en ocasiones los procesadores de gama baja fallan bastante en operaciones de
	 * doble precisión, por lo que la imágen blur se verá desplazada, más aún con cada sample, este
	 * parámetro se usa para corregir la desviación en cada sample.
	 */
	vars: {blurCompensation:0},
	init: function(){},
	getContext: function(elem){
		if(!elem.tagName && elem.tagName.toUpperCase() != "CANVAS"){return;}
		var ctx = elem.getContext("2d");ctx.canvasWidth = elem.width;ctx.canvasHeight = elem.height;
		ctx = extend(ctx,{
			$arc: function(x,y,radius,startAngle,endAngle,anticlockwise){this.arc(x,y,radius,startAngle,endAngle,anticlockwise);return this;},
			$at: function(obj){for(var o in obj){this[o] = obj[o];}return this;},
			$beginPath: function(){this.beginPath();return this;},
			$bezierCurveTo: function(cp1x,cp1y,cp2x,cp2y,x,y){this.bezierCurveTo(cp1x,cp1y,cp2x,cp2y,x,y);return this;},
			$clip: function(){this.clip();return this;},
			$closePath: function(){this.closePath();return this;},
			$createLinearGradient: function(x1,y1,x2,y2,start,end){var g = this.createLinearGradient(x1,y1,x2,y2);g.addColorStop(0,start);g.addColorStop(1,end);this.fillStyle = g;return this;},
			$drawImage: function(img,x,y,w,h){/* drawImage no permite pasar false o null como w o h */if(!w || !h){this.drawImage(img,x,y);return this;}else{this.drawImage(img,x,y,w,h);return this;}},
			$empty: function(offsetTop,offsetRight,offsetBottom,offsetLeft){
				offsetTop = parseFloat(offsetTop) || 0;offsetRight = parseFloat(offsetRight) || 0;offsetBottom = parseFloat(offsetBottom) || 0;offsetLeft = parseFloat(offsetLeft) || 0;
				this.clearRect(0+offsetLeft,0+offsetTop,this.canvasWidth+offsetRight,this.canvasHeight+offsetBottom);return this;
			},
			$fill: function(){this.fill();return this;},
			$fillRect: function(x,y,width,height){this.fillRect(x,y,width,height);return this;},
			$fillText: function(text,x,y){this.fillText(text,x,y);return this;},
			$horizontalLine: function(y){this.$beginPath().$moveTo(0,y-1).$lineTo(this.canvasWidth,y-1).$lineTo(this.canvasWidth,y).$lineTo(0,y).$closePath().$fill();return this;},
			$lineTo: function(x,y){this.lineTo(x,y);return this;},
			$moveTo: function(x,y){this.moveTo(x,y);return this;},
			$restore: function(){this.restore();return this;},
			$save: function(){this.save();return this;},
			$stroke: function(){this.stroke();return this;},
			$strokeText: function(text,x,y){this.strokeText(text,x,y);return this;},
			$translate: function(x,y){this.translate(x,y);return this;}
		});
		return ctx;
	},
	newImage: function(src,callback){var img = new Image();img.onload = function(){callback(img);};img.src = src;},
	image_resize: function(src,width,height,adjust,callback){return this.imageResize(src,width,height,adjust,callback);},
	imageResize: function(src,width,height,adjust,callback){
		this.newImage(src,function(img){
			var $maxWidth = width;var $maxHeight = height;var $imgWidth = img.width;var $imgHeight = img.height;
			$imgRatio = $imgWidth/$imgHeight;$maxRatio = $maxWidth/$maxHeight;

			switch(adjust){
				case 'max':if($imgRatio>$maxRatio){$maxHeight = $imgHeight * ($maxWidth/$imgWidth);}else{$maxWidth = $imgWidth * ($maxHeight/$imgHeight);}break;
				case 'min':if($imgRatio>$maxRatio){$maxWidth = $imgWidth * ($maxHeight/$imgHeight);}else{$maxHeight = $imgHeight * ($maxWidth/$imgWidth);}break;
				default:return;
			}

			if(width > $maxWidth){width = $maxWidth;}
			if(height > $maxHeight){height = $maxHeight;}

			var canvas = $C('CANVAS',{'width':width,'height':height});var ctx = this.getContext(canvas);

			$offsetLeft = (width - $maxWidth)/2;
			$offsetTop = (height - $maxHeight)/2;
			ctx.drawImage(img,$offsetLeft,$offsetTop,$maxWidth,$maxHeight);

			callback(canvas.toDataURL('image/png'));
		}.bind(this));
	},
	blurEffect: function(r,samples){
		if(!samples){samples = 2;}
		var blur = $C('canvas',{width:r.width,height:r.height});var bctx = _lainCanvas.getContext(blur);bctx.drawImage(r,0,0);
		var aux = $C('canvas',{width:r.width,height:r.height});var actx = _lainCanvas.getContext(aux);

		var pW = r.width/2;var pH = r.height/2;
		/* blurCompensation normalmente debe ser 0 */
		for(var i = 0;i<samples;i++){actx.drawImage(blur,0,0,pW,pH);bctx.$empty().drawImage(aux,0,0,pW,pH,0,0,r.width,r.height);}
		return blur;
	}
});