📄 17.7 滑动条（二）.htm

📁 一些javascript的小例子希望对初学者有更好的帮助
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<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=gb2312">
<title>滑块条</title>
<style type="text/css">
#trackBar
{
    background-color:#666666;
}

#trackBar_slider
{
    border:1px solid #808080;
    background-color:#FFFFFF;
}

#trackBar1
{
    background-color:blue;
}

#trackBar1_slider
{
    border:1px solid #808080;
    background-color:#FFFFFF;
}
</style>
</head>
<body>
<div id="info"></div>
<div id="trackBar1"> </div>
<script type="text/javascript" language="javascript">
//对象未创建完成之前，不能在函数之中用this
function setTrackBar(trackBar, min, max, barPos)//指定的div，最小值，最大值和位置
{
    this.trackBar = trackBar;                 //承载滑动条的对象
    this.sliderIdStr = trackBar + "_slider";       //滑动条
    this.trackBarId = document.getElementById(this.trackBar);  //获取div
    this.sliderId = null;                                           //未创建滑动条对象
    this.min = (min>=0)?min:0;                                      //最小值不能小于0
    this.max = (max>=min)?max:min;                                  //最大值必须大于最小值
    this.barPos = (barPos>=min && barPos<=max)?barPos:min;                      //位置必须在最大和最小之间
    
    this.orientation = "h";                                         //设置对象和滑动条的位置
    this.trackBarWidth = 100;
    this.trackBarHeight = 10
    this.sliderWidth = 10;
    this.sliderHeight = 10;
    this.Create = Create; 
    this.draging = false;
    this.offset = 0;
    
    this.BeforeDrag = BeforeDrag;                                    //绑定滑动事件
    this.OnDrag = OnDrag;
    this.EndDrag = EndDrag;
}
function Create(trackBar1)                                          //创建滑动条的方法
{
    this.trackBarId.innerHTML = "<div id=\"" + this.sliderIdStr + "\"" + " onmousedown=\"javascript:BeforeDrag(" + trackBar1 + ");\"" + " style=\"position:relative;cursor:n-resize;\"></div>";
    this.sliderId = document.getElementById(this.sliderIdStr);
    this.sliderId.style.pixelTop = this.trackBarHeight - ((this.trackBarHeight-this.sliderHeight)*this.barPos)/(this.max-this.min) - this.sliderHeight;
    this.trackBarId.style.width = this.trackBarWidth;               //设置滑动条的初始位置
    this.trackBarId.style.height = this.trackBarHeight;
    this.sliderId.style.width = this.sliderWidth;
    this.sliderId.style.height = this.sliderHeight;
    
    return true;
}

var curTrackBar = null;

//准备拖拽
function BeforeDrag(trackBar)
{
    if (event.button != 1)                  //如果不是鼠标左键，则返回
    {
        return;
    }
    document.body.style.cursor = "n-resize";//鼠标的样式
    curTrackBar = trackBar;
    curTrackBar.draging = true;
    curTrackBar.offset = curTrackBar.trackBarId.style.pixelTop + curTrackBar.sliderId.style.pixelTop+curTrackBar.sliderId.offsetHeight- event.clientY;
}


function OnDrag()                           //实现拖拽的方法
{
    if(!curTrackBar || !curTrackBar.draging)
    {
        return;
    }
    event.returnValue = false;
    var phyPos = 0;
    if (curTrackBar.orientation !== "h")
    {
        phyPos = curTrackBar.trackBarId.style.pixelTop + curTrackBar.trackBarId.offsetHeight - event.clientY - curTrackBar.offset;
        if (phyPos <= 0)
        {
            phyPos = 0;                     //如果拖动到最底端
        }
        else if(phyPos >= (curTrackBar.trackBarId.offsetHeight-curTrackBar.sliderId.offsetHeight))
        {
            phyPos = curTrackBar.trackBarId.offsetHeight - curTrackBar.sliderId.offsetHeight;
        }
                                                //改变滑动条的位置
        curTrackBar.sliderId.style.pixelTop = curTrackBar.trackBarId.offsetHeight - phyPos - curTrackBar.sliderId.offsetHeight;
        curTrackBar.barPos = parseInt(((curTrackBar.max-curTrackBar.min)*phyPos/(curTrackBar.trackBarId.offsetHeight-curTrackBar.sliderId.offsetHeight)));
    }

    OnTrackBarTxt();
}
function EndDrag()                      //结束拖拽
{
    if (!curTrackBar)
    {
        return;
    }
    document.body.style.cursor = "default";
    curTrackBar.draging = false;
}

function OnTrackBarTxt()           //拖拽时，改变滑动条的值
{
    document.getElementById("info").innerHTML = curTrackBar.barPos+ " / " + curTrackBar.max;
}

document.onmousemove = OnDrag;              //鼠标移动时，实现拖拽-开始滑动
document.onmouseup = EndDrag;               //鼠标离开时，结束拖拽-即结束滑动
var trackBarObj1 = new setTrackBar("trackBar1", 0, 100,100);//配置滑动条，指定最小值和最大值
trackBarObj1.orientation = "v";                            //滑动条的方法-垂直
trackBarObj1.trackBarWidth = 15;                            //对象的宽度
trackBarObj1.trackBarHeight = 100;                          //对象的高度
trackBarObj1.sliderWidth = 15;                              //滑动条的宽度
trackBarObj1.sliderHeight = 10;                             //滑动条的高度
trackBarObj1.Create("trackBarObj1");                        //创建滑动条
</script>
</body>
</html>
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