/*
instance:创建的实例名称
marquee:滚动区域容器的ID，要求无填充，无边框，overflow为hidden
direction:滚动方向，值分别为：up,down,left,right
delay:滚动的速度，值最小为1，值越小越快
amount:滚动步进量，值最小为1，值越大越快
*/


function Marquee(instance, marquee, direction, delay, amount) {
    this.instance = instance; //实例名称
    this.marquee = document.getElementById(marquee);
    this.delay = delay;
    if (this.delay == null) {
        this.delay = 1;
    }
    this.amount = amount;
    if (this.amount == null) {
        this.amount = 1;
    }
    this.direction = direction;
    this.width = this.marquee.clientWidth;
    this.height = this.marquee.clientHeight;
    this.container = document.createElement("table");
    this.container.border = 0;
    this.container.cellspacing = "0"
    this.container.cellpadding = "0"
    var _HTML = this.marquee.innerHTML;
    this.marquee.innerHTML = "";
    this.marquee.appendChild(this.container);
    var _tr = this.container.insertRow(this.container.rows.length);
    var _td = _tr.insertCell(_tr.cells.length);
    _td.innerHTML = _HTML;
    this.scrollHeight = this.container.clientHeight;
    this.scrollWidth = this.container.clientWidth;
    switch (this.direction.toLowerCase()) {
        case "up":
        case "down":
            if (this.scrollHeight >= this.height) {
                var _tr = this.container.insertRow(this.container.rows.length);
                var _td = _tr.insertCell(_tr.cells.length);
                _td.innerHTML = _HTML;
                this.scrollHeight = this.container.clientHeight;
            }
            if (this.direction.toLowerCase() == "down") {
                this.marquee.scrollTop = this.scrollHeight / 2;
            }
            break;
        default:
            if (this.scrollWidth >= this.width) {
                var _td = _tr.insertCell(_tr.cells.length);
                _td.innerHTML = _HTML;
                this.scrollWidth = this.container.clientWidth;
            }

    }

    this.marquee.m = this;

    this.intervalId = null;
    this.marquee.onmouseover = function() {
        this.m.Stop();
    }
    this.marquee.onmouseout = function() {
        this.m.Start();
    }
    this.Start();
}
Marquee.prototype.Start = function() {
    this.intervalId = setInterval(this.instance + ".Scroll()", this.delay)
    //this.Scroll();
}
Marquee.prototype.Stop = function(sender) {
    if (this.intervalId != null) {
        clearInterval(this.intervalId);
    }
}
Marquee.prototype.Scroll = function() {
    switch (this.direction.toLowerCase()) {
        case "up":
            if ((this.marquee.scrollTop + this.height) >= this.scrollHeight) {
                this.marquee.scrollTop -= this.scrollHeight / 2
            }
            if (this.scrollHeight > this.height) {
                this.marquee.scrollTop += this.amount;
            }
            break;
        case "down":
            if (this.marquee.scrollTop <= 0) {
                this.marquee.scrollTop += this.scrollHeight / 2
            }
            if (this.scrollHeight > this.height) {
                this.marquee.scrollTop -= this.amount;
            }
            break;
        case "right":
            if (this.marquee.scrollLeft <= 0) {
                this.marquee.scrollLeft += this.scrollWidth / 2
            }
            if (this.scrollWidth > this.width) {
                this.marquee.scrollLeft -= this.amount;
            }
            break;
        default:
            if ((this.marquee.scrollLeft + this.width) >= this.scrollWidth) {
                this.marquee.scrollLeft -= this.scrollWidth / 2
            }
            if (this.scrollWidth > this.width) {
                this.marquee.scrollLeft += this.amount;
            }
    }
}