var elementsList = null;
var offsetMove =0 ;
var elementWidthDft = 0 ;
var maxOffsetMoveRight = 0 ;
var maxOffsetMoveLeft = 0 ;
var nbElementViewable = 0 ;

function rollRight() {
    var elementListLeft = elementsList.style.left ;
    if(offsetMove != 0 && elementListLeft != (maxOffsetMoveLeft+"px")){
        elementsList.style.left = parseInt(elementsList.style.left) - elementWidthDft + "px" ;
        setTimeout("rollRight()", elementWidthDft);
        offsetMove = offsetMove - elementWidthDft ;
        return;
    }
    else{
        offsetMove = elementWidthDft * nbElementViewable;
        var navRight = getElement("navright", true, "") ;
        var navLeft = getElement("navleft", true, "") ;
        
        var widthBlockDft = elementWidthDft * nbElementViewable ;
        
        var elementListLeftInt = parseInt(elementListLeft.split("px")[0]) ;
        if(elementListLeftInt < (maxOffsetMoveLeft+widthBlockDft) && navRight && navLeft){
            hideBloc(navRight) ;
            displayBloc(navLeft) ;
        }
        else{
            displayBloc(navLeft) ;
            displayBloc(navRight) ;
        }
    }
}


function rollLeft() {
    var elementListLeft = elementsList.style.left ;
    if(offsetMove != 0 && elementListLeft != "0px") {
        elementsList.style.left = parseInt(elementsList.style.left) + elementWidthDft + "px" ; 
        
        setTimeout('rollLeft()', elementWidthDft);
        offsetMove = offsetMove - elementWidthDft ;        
        return;
    }
    else{
        offsetMove = elementWidthDft * nbElementViewable;
        var navRight = getElement("navright", true, "") ;
        var navLeft = getElement("navleft", true, "") ;
        
        if(elementListLeft == "0px" && navLeft && navRight){
            hideBloc(navLeft) ;
            displayBloc(navRight) ;
        }
        else{
            displayBloc(navLeft) ;
            displayBloc(navRight) ;
        }        
    }
}


function initRoll(_elementsList, _elementWidthDft, _nbElementViewable, _widthTheElement) {
    elementsList = document.getElementById(_elementsList);    
    if (elementsList == null) {
        return;
    }
    elementsList.style.width = _widthTheElement + "px" ;
                
    elementsList.style.left = 0 ;
    var navLeft = getElement("navleft", true, "") ;
    if(navLeft){
        hideBloc(navLeft) ;
    }
    
    elementWidthDft = _elementWidthDft ;
    nbElementViewable = _nbElementViewable ;
    offsetMove = _elementWidthDft * _nbElementViewable;
    
    maxOffsetMoveLeft = _widthTheElement-(2*_widthTheElement) ;
    
    if(_widthTheElement<=offsetMove){
        var navRight = getElement("navright", true, "") ;
        if(navRight){
            hideBloc(navRight) ;
        }
    }
}