var $i = 0;

function getSwapItems($type)
{
    if($type == 'CoverI11l') {
        var $item = 'CoverI11l';
    } else if($type == 'CoverPsycho') {
        var $item = 'CoverPsycho';
    } else if($type == 'CoverMedia') {
        var $item = 'CoverMedia';
    } else if($type == 'CoverHistory') {
        var $item = 'CoverHistory';
    } else if($type == 'Psycho') {
        var $item = new Array(
            'CoverPsycho01',
            'CoverPsycho02'
            );
    } else if($type == 'Clinical') {
        var $item = new Array(
            'CoverClinical01',
            'CoverClinical02'
            );
    } else if($type == 'Social') {
        var $item = new Array(
            'CoverSocial01',
            'CoverSocial02'
            );
    } else if($type == 'Media') {
        var $item = new Array(
            'CoverMedia01',
            'CoverMedia02'
            );
    } else if($type == 'History') {
        var $item = new Array(
            'CoverHistory01',
            'CoverHistory02'
            );
    } else if($type == 'Japanese') {
        var $item = new Array(
            'CoverJapanese01',
            'CoverJapanese02'
            );
    } else if($type == 'Kyoto') {
        var $item = new Array(
            'CoverKyoto01',
            'CoverKyoto02'
            );
    } else if($type == 'Beauty') {
        var $item = new Array(
            'CoverBeauty01',
            'CoverBeauty02'
            );
    } else if($type == 'English') {
        var $item = new Array(
            'CoverEnglish01',
            'CoverEnglish02'
            );
    }
    return $item;
}

// the function that performs the fade
function swapScreen($type)
{
    $item = getSwapItems($type);
    if(IsArray($item)) {
        $i++;
        if($i == 2) {
            $i = 0;
        }
        Effect.Appear($item[$i], { duration:0.5, from:0.0, to:1.0 });
    } else {
        Effect.Appear($item, { duration:0.5, from:0.0, to:1.0 });
    }
}

function resetScreen($type)
{
    $item = getSwapItems($type);
    if(IsArray($item)) {
        Effect.Fade($item[$i], { duration:0.5, from:1.0, to:0.0 });
    } else {
        Effect.Fade($item, { duration:0.5, from:1.0, to:0.0 });
    }
}

function IsArray($item)
{
    return($item.constructor===Array);
}

function swapButton($ID)
{
    var $img = $ID;
    document.images[$img].src = "./images/TopPage/" + $img + "H.gif";
}

function resetButton($ID)
{
    var $img = $ID;
    document.images[$img].src = "./images/TopPage/" + $img + ".gif";
}