function RSPlug_Zoom (thumb, zoomContainer, fullImgUrl){
	this.mouseOverCallback = this.mouseOutCallback = null;
	this.containerThumb = null;
	this.options = { 
		surlayerOpacity: 50,
		surlayerBgColor: '#fff',
		showIfInsideFor: 0,
		hideIfOutsideFor: 0
	};
	
	if (typeof(thumb) == 'string'){
		thumb = document.getElementById(thumb);
	}
	if (thumb){
		this.thumb = thumb;
		if (typeof(zoomContainer) == 'string'){
			zoomContainer = document.getElementById(zoomContainer);
		}
		this.zoomContainer = zoomContainer;
		
		if (arguments.length > 3){
			this.init (fullImgUrl, arguments[3]);
		} else {
			this.init (fullImgUrl);
		}
	}
}

RSPlug_Zoom.prototype.init = function (fullImgUrl){
	if (arguments.length > 1){
		if (arguments[1].surlayerOpacity && !isNaN(arguments[1].surlayerOpacity) && arguments[1].surlayerOpacity <= 100 && arguments[1].surlayerOpacity >= 0){
			this.options.surlayerOpacity = arguments[1].surlayerOpacity; 
		}
		if (arguments[1].surlayerBgColor && typeof(arguments[1].surlayerBgColor) == 'string' && '' != arguments[1].surlayerBgColor){
			this.options.surlayerBgColor = arguments[1].surlayerBgColor;
		}
		if (arguments[1].showIfInsideFor && !isNaN(arguments[1].showIfInsideFor) && arguments[1].showIfInsideFor >= 0){
			this.options.showIfInsideFor = arguments[1].showIfInsideFor; 
		}
		if (arguments[1].hideIfOutsideFor && !isNaN(arguments[1].hideIfOutsideFor) && arguments[1].hideIfOutsideFor >= 0){
			this.options.hideIfOutsideFor = arguments[1].hideIfOutsideFor; 
		}
	}
	
	this.isShowed = false;
	this.showIfInsideForTimer = null;
	this.hideIfOutsideForTimer = null;
	this.lastPosMouse = { x: 0, y: 0 };
	
	this.fullImgUrl = fullImgUrl;
	this.deadZone = { x: 0, y: 0 };
	
	this.prepareZoom ();
	this.prepareThumb ();
}

RSPlug_Zoom.prototype.prepareZoom = function (){
	this.zoomContainer.style.display = 'none';
	this.zoomContainer.style.overflow = 'hidden';
	
	// Preload of the full image
	this.bigImg = new Image();
	this.bigImg.src = this.fullImgUrl;
	this.zoomImg = document.createElement('img');
	this.zoomImg.setAttribute('src', this.fullImgUrl);
	with (this.zoomImg.style){
		position = 'absolute';
		left = '0';
		top = '0';
	}
	this.zoomContainer.innerHTML = '';
	this.zoomContainer.appendChild(this.zoomImg);
};


RSPlug_Zoom.prototype.registerPosMouse = function (event){
	var posImg = RSPlug_Zoom.findPos (this.thumb);
	this.lastPosMouse = RSPlug_Zoom.getMousePos (event, posImg);
};

RSPlug_Zoom.prototype.mouseMove = function (event){
	this.registerPosMouse(event);
	if (this.isShowed){
		this.execMouseMove(event);
	}
};

RSPlug_Zoom.prototype.execMouseMove = function (event){
	var posImg = RSPlug_Zoom.findPos (this.thumb);
	var dimImg = RSPlug_Zoom.getDimensions (this.thumb);
	var dimBigImg = RSPlug_Zoom.getDimensions (this.bigImg);
	var dimContainer = RSPlug_Zoom.getDimensions (this.zoomContainer);
	
	var scaleX = (dimBigImg.width - dimContainer.width) / dimImg.width;
	var scaleY = (dimBigImg.height - dimContainer.height) / dimImg.height;
	if (scaleX < 0){ scaleX *= -1; }
	if (scaleY < 0){ scaleY *= -1; }
	if (scaleX == 0){ scaleX = 1; }
	if (scaleY == 0){ scaleY = 1; }
	
	var scaleSLX = dimBigImg.width / dimImg.width;
	var scaleSLY = dimBigImg.height / dimImg.height;
	
	var dimSurLayer = { 
		width: parseInt(dimContainer.width / scaleSLX), 
		height: parseInt(dimContainer.height / scaleSLY)
	};
	
	this.surLayer.style.width = dimSurLayer.width +'px';
	this.surLayer.style.height = dimSurLayer.height +'px';
	
	// Calcul de la bordure css du surlayer afin la prendre en compte dans le calcul de la zone morte (deadZone) 
	this.borderSurLayer = { x: 0, y: 0 };
	if (this.surLayer.offsetWidth > dimSurLayer.width){
		this.borderSurLayer.x = Math.ceil(this.surLayer.offsetWidth) - parseInt(dimSurLayer.width);
	}
	if (this.surLayer.offsetHeight > dimSurLayer.height){
		this.borderSurLayer.y = Math.ceil(this.surLayer.offsetHeight) - parseInt(dimSurLayer.height);
	}
	
	this.deadZone.x = (dimSurLayer.width + this.borderSurLayer.x) / 2;
	this.deadZone.y = (dimSurLayer.height + this.borderSurLayer.y) / 2;

	if (this.deadZone.x > 0){ dimImg.width -= this.deadZone.x *2; }
	if (this.deadZone.y > 0){ dimImg.height -= this.deadZone.y *2; }

	//var mousePosition = RSPlug_Zoom.getMousePos (event, posImg);
	var mousePosition = this.lastPosMouse;
	
	var posMouse = { left: (mousePosition.x - posImg.left), top: (mousePosition.y - posImg.top) };

	if (this.deadZone.x > 0){
		posMouse.left -= this.deadZone.x;
		if (posMouse.left < 0){
			posMouse.left = 0;
		}
		if (posMouse.left > dimImg.width){
			posMouse.left = dimImg.width;
		}
	}
	if (this.deadZone.y > 0){
		posMouse.top -= this.deadZone.y;
		if (posMouse.top < 0){
			posMouse.top = 0;
		}
		if (posMouse.top > dimImg.height){
			posMouse.top = dimImg.height;
		}
	}

	var paddingLeft = paddingTop = 0; 
	
	if (dimContainer.width > dimBigImg.width){
		paddingLeft = (dimContainer.width - dimBigImg.width) / 2; 
	}
	if (dimContainer.height > dimBigImg.height){
		paddingTop = (dimContainer.height - dimBigImg.height) / 2; 
	}
	
	var scaleX = (dimBigImg.width - dimContainer.width) / dimImg.width;
	var scaleY = (dimBigImg.height - dimContainer.height) / dimImg.height;
	if (scaleX < 0){
		scaleX *= -1;
	}
	if (scaleY < 0){
		scaleY *= -1;
	}
	
	var bgLeft = (posMouse.left * scaleX * -1) - paddingLeft;
	var bgTop = (posMouse.top * scaleY * -1) - paddingTop;
	
	this.zoomImg.style.left = bgLeft + 'px';
	this.zoomImg.style.top = bgTop + 'px';
	
	this.surLayer.style.left = (parseInt(posMouse.left)) + 'px';
	this.surLayer.style.top = (parseInt(posMouse.top)) + 'px';
};

RSPlug_Zoom.prototype.execMouseOver = function (event){
	this.isShowed = true;
	this.zoomContainer.style.display = 'block';
	this.surLayer.style.display = 'block';
	this.execMouseMove(event);
	if (null !== this.mouseOverCallback){
		this.mouseOverCallback();
	}
};

RSPlug_Zoom.prototype.execMouseOut = function (event){
	this.isShowed = false;
	this.zoomContainer.style.display = 'none';
	this.surLayer.style.display = 'none';
	if (null !== this.mouseOutCallback){
		this.mouseOutCallback();
	}
};

RSPlug_Zoom.prototype.mouseOver = function (event){
	if (null !== this.hideIfOutsideForTimer){
		clearTimeout(this.hideIfOutsideForTimer);
		this.hideIfOutsideForTimer = null;
	}
	if (this.options.showIfInsideFor > 0){
		if (null === this.showIfInsideForTimer){
			var inst = this;
			this.showIfInsideForTimer = setTimeout(function(){ inst.execMouseOver(event); inst.showIfInsideForTimer = null; }, this.options.showIfInsideFor);
		}
	} else {
		this.execMouseOver(event);
	}
};

RSPlug_Zoom.prototype.mouseOut = function (event){
	if (null !== this.showIfInsideForTimer){
		clearTimeout(this.showIfInsideForTimer);
		this.showIfInsideForTimer = null;
	}
	if (this.options.hideIfOutsideFor > 0){
		if (null === this.hideIfOutsideForTimer){
			var inst = this;
			this.hideIfOutsideForTimer = setTimeout(function(){ inst.execMouseOut(event); inst.hideIfOutsideForTimer = null; }, this.options.hideIfOutsideFor);
		}
	} else {
		this.execMouseOut(event);
	}
};

RSPlug_Zoom.prototype.setMouseOverCallback = function (callback){
	this.mouseOverCallback = callback;
};

RSPlug_Zoom.prototype.setMouseOutCallback = function (callback){
	this.mouseOutCallback = callback;
};

RSPlug_Zoom.prototype.prepareThumb = function (){
	if (null !== this.containerThumb){
		this.containerThumb.parentNode.insertBefore(this.thumb, this.containerThumb);
		this.containerThumb.parentNode.removeChild(this.containerThumb);
	}
	this.containerThumb = document.createElement('div');
	this.containerThumb.style.position = 'relative';
	this.thumb.parentNode.insertBefore(this.containerThumb, this.thumb);
	this.containerThumb.appendChild(this.thumb);
	
	this.surLayer = document.createElement('div');
	this.surLayer.setAttribute('id', 'RSPlug_Zoom_surLayer');
	with (this.surLayer.style){
		background = this.options.surlayerBgColor;
		opacity = (this.options.surlayerOpacity / 100);
		MozOpacity = (this.options.surlayerOpacity / 100);
		filter = 'alpha(opacity=' + this.options.surlayerOpacity + ')';
		display = 'none';
		position = 'absolute';
		zIndex = '1000';
	}
	this.containerThumb.appendChild(this.surLayer);
	
	var dimImg = RSPlug_Zoom.getDimensions(this.thumb);
	this.zoomEventCapturer = document.createElement('div');
	with (this.zoomEventCapturer.style){
		position = 'absolute';
		top = '0';
		left = '0';
		zIndex = '1010';
		width = '100%';
		height = '100%';
		/* Pour une compatibilité IE... */
		background = 'transparent url(/rsplug/zoom/zoom_transparent.gif) left top repeat';
	}
	this.containerThumb.appendChild(this.zoomEventCapturer);
	
	var inst = this;
	RSPlug_Zoom.addEvent (inst.zoomEventCapturer, 'mousemove', function (e){ inst.mouseMove(e); } );
	RSPlug_Zoom.addEvent (inst.zoomEventCapturer, 'mouseover', function (e){ inst.mouseOver(e); } );
	RSPlug_Zoom.addEvent (inst.zoomEventCapturer, 'mouseout', function (e){ inst.mouseOut(e); } );
};


/* Méthodes statiques  
/*********************/

RSPlug_Zoom.findPos = function (obj) { 
	var curleft = curtop = 0;
	if (obj.offsetParent) {
		do {
			curleft += obj.offsetLeft;
			curtop += obj.offsetTop;
		} while (obj = obj.offsetParent);
	} 
	return { left: curleft, top: curtop };
};

RSPlug_Zoom.getMousePos = function (evenement, decalage) { 
	if (evenement.pageX){
		return {x: evenement.pageX, y: evenement.pageY };
	}
	return {x: (evenement.offsetX + decalage.left), y: (evenement.offsetY + decalage.top) };
};

RSPlug_Zoom.getDimensions = function (obj) {
	if (obj.tagName.toLowerCase() == 'img'){
		return { width: obj.width, height: obj.height };
	}
	return { width: obj.offsetWidth, height: obj.offsetHeight };
};

RSPlug_Zoom.addEvent = function (element, eventName, callback){
	if (element.addEventListener){
		element.addEventListener(eventName, callback, false);
	} else if (element.attachEvent){
		element.attachEvent('on' + eventName, callback);
	}
};