var isTimerOn = false;
var currentLine = 1;
var lineCount = 6;
var timeOut;
var lineIDPrefix = 'line';
var lineRefresh = 3500;

window.onload = initPage;

function initPage() {
    startTimer();
}

function startTimer() {
    if (!isTimerOn) {
        startLines();
    }
}

function startLines() {

    isTimerOn = true;
    var stopTimer = false;
    showHideLine(currentLine, 'none');

    if (currentLine == lineCount) {
        currentLine = 1;
        stopTimer = true;
    }
    else
        currentLine++;

    showHideLine(currentLine, 'block');
    timeOut = setTimeout("startLines()", lineRefresh);
}

function jumpLine(jump) {
    if (jump > 0) {
        startLines();
        stopLines();
    }
    else {
        stopLines();
        showHideLine(currentLine, 'none');
        currentLine = currentLine - 2;

        if (currentLine == 0)
            currentLine = lineCount;
        else if (currentLine < 0)
            currentLine = (lineCount - 1);

        startLines();
        stopLines();
    }
}

function showHideLine(LineId, showHide) {
    imgObj = document.getElementById(lineIDPrefix + LineId);
    imgObj.style.display = showHide;
}

function stopLines() {
    clearTimeout(timeOut);
    isTimerOn = false;
}