JTrackBar水平拖动效果

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<!--
/*
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JTrackBar
初始日期：2007/07/11
Author:xlingFairy
Blog:http://xling.blueidea.com

目前只能生水平的，垂直的还没有写。
设计功能：
当改变时，触发事件onChange,并传当前值。

2007/07/12
加入拖动功能。

2007/07/13
加入皮肤功能

未做功能：指定trackFrequence，你可以自己试着修改一下。

请尊重劳动成果！不得删除原作都信息！后果自负！
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*/
function JPos(){

}

JPos.getAbsPos = function(pTarget){
var _x = 0;
var _y = 0;
while(pTarget.offsetParent){
_x += pTarget.offsetLeft;
_y += pTarget.offsetTop;
pTarget = pTarget.offsetParent;
}
_x += pTarget.offsetLeft;
_y += pTarget.offsetTop;

return {x:_x,y:_y};
}

JPos.getMousePos = function(evt){
var _x,_y;
evt = evt || window.event;
if(evt.pageX || evt.pageY){
_x = evt.pageX;
_y = evt.pageY;
}else{
_x = evt.clientX + document.body.scrollLeft - document.body.clientLeft;
_y = evt.clientY + document.body.scrollTop - document.body.clientTop;
}
return {x:_x,y:_y};
}

function JTrackBar(pParent){
var self = this;

var $ = function(pId){
return document.getElementById(pId);
}

var $c = function(pTag){
return document.createElement(pTag);
}

var body = $(pParent) || document.body;
var oOutline = null;
var oTrackArea = null;
var oBtnPointer = null;
var oArrBtnLeft = oArrBtnRight = oArrBtnUp = oArrBtnDown = null;

var inDrag = false;
var dragStartPos = null;

var maxPosition = 100; //最大刻度
var minPosition = 0; //最小刻度
var position = 0; //当前位置
var trackFrequence = 10; //点击一次移动多少刻度

this.setRange = function(pMin,pMax){
maxPosition = Math.max(pMin,pMax);
minPosition = Math.min(pMin,pMax);
}

var outlineWidth,trackAreaWidth,preFrequenceWidth;

this.onChange = new Function();

var getRunStyle = function(pObj,pProperty){
try{
if(pObj.currentStyle)
return eval("pObj.currentStyle." + pProperty);
else
return document.defaultView.getComputedStyle(pObj,"").getPropertyValue(pProperty);
}catch(e){
alert(e);
}
}

/*-----------------------------------------------------*/
var createOutline = function(pWidth){
oOutline = $c("DIV");
body.appendChild(oOutline);
oOutline.className = "JTrackBarStand";
oOutline.style.width = pWidth + "px";
//oOutline.style.height = "15px";
oOutline.style.overflow = "hidden";
}
/*-----------------------------------------------------*/
var createArrBtn = function(pDirection){
var arrBtn = $c("DIV");
switch(pDirection){
case "LEFT":
arrBtn.className = "btnLeft";
arrBtn.style.styleFloat = "left";
arrBtn.style.cssFloat = "left";
break;
case "RIGHT":
arrBtn.className = "btnRight";
arrBtn.style.styleFloat = "left";
arrBtn.style.cssFloat = "left";
break;
case "UP":
arrBtn.className = "btnUp";
break;
case "DOWN":
arrBtn.className = "btnDown";
break;
}

arrBtn.direction = pDirection;
arrBtn.onclick = arrBtn_click;
return arrBtn;
}

var arrBtn_click = function(evt){

evt = window.event || evt;
var o = evt.srcElement || evt.target;

switch(o.direction){
case "LEFT":
if(position <= minPosition)
return;
self.setPositionBy( -trackFrequence);
break;
case "RIGHT":
if(position >= maxPosition)
return;
self.setPositionBy(trackFrequence);
break;
}
}

var trackarea_click = function(evt){
evt = window.event || evt;
var mPos = JPos.getMousePos(evt);

var pos_ = JPos.getAbsPos(oTrackArea);
var w_ = parseInt(getRunStyle(oBtnPointer,"width"));

self.setPosition(parseInt((mPos.x - pos_.x) / preFrequenceWidth));
}

var createHTrackArea = function(){
var w_ = parseInt(getRunStyle(oArrBtnLeft,"width"));
trackAreaWidth = outlineWidth - 2 * w_;
preFrequenceWidth = trackAreaWidth / (maxPosition - minPosition);

oTrackArea = $c("DIV");
oOutline.appendChild(oTrackArea);

oTrackArea.onclick = trackarea_click;

oTrackArea.className = "trackArea";
oTrackArea.style.width = trackAreaWidth + "px";
oTrackArea.style.styleFloat = "left";
oTrackArea.style.cssFloat = "left";
}

var recalcTrackArea = function(){
var w_ = parseInt(getRunStyle(oArrBtnLeft,"width"));
trackAreaWidth = outlineWidth - 2 * w_;
preFrequenceWidth = trackAreaWidth / (maxPosition - minPosition);

oTrackArea.style.width = trackAreaWidth + "px";
}

var pointer_mousedown = function(evt){
inDrag = true;
dragStartPos = JPos.getMousePos(evt);
body.onmousemove = pointer_mousemove;
body.onmouseup = pointer_mouseup;
body.onmouseout = pointer_mouseout;
}

var pointer_mousemove = function(evt){
if(!inDrag) return;
//evt = window.event || evt;
//var x_ = evt.clientX;
//window.status = x_ + " " + dragStartPos.x;
//self.setPositionBy(x_ - dragStartPos.x);

//window.status += " " + evt.clientX;

var mPos = JPos.getMousePos(evt);
var pos_ = JPos.getAbsPos(oTrackArea);

self.setPosition(parseInt((mPos.x - pos_.x) / preFrequenceWidth));
}

var pointer_mouseup = function(){
inDrag = false;
}

var pointer_mouseout = function(){
//inDrag = false;
}

var createHPointer = function(){
oBtnPointer = $c("DIV");
oOutline.appendChild(oBtnPointer);

//oBtnPointer.onclick = trackarea_click;
oBtnPointer.onmousedown = pointer_mousedown;
//oOutline.onmousemove = oBtnPointer.onmousemove = pointer_mousemove;
//oBtnPointer.onmouseup = pointer_mouseup;
//oBtnPointer.onmouseout = pointer_mouseout;

oBtnPointer.className = "btnPointer";
oBtnPointer.style.position = "absolute";

var w_ = parseInt(getRunStyle(oBtnPointer,"width"));

var pos_ = JPos.getAbsPos(oTrackArea);
oBtnPointer.style.left = pos_.x - w_/2 + "px";
oBtnPointer.style.top = pos_.y + "px";
oBtnPointer.style.cssText += "left:" + (pos_.x - w_/2) + "px;top:" + pos_.y + "px;";
}

/*-----------------------------------------------------*/
this.createHTrackBar = function(pWidth){
outlineWidth = pWidth;
createOutline(pWidth);

oArrBtnLeft = createArrBtn("LEFT");
oOutline.appendChild(oArrBtnLeft);

createHTrackArea();

oArrBtnRight = createArrBtn("RIGHT");
oOutline.appendChild(oArrBtnRight);

createHPointer();
}
/*-----------------------------------------------------*/

this.setPositionBy = function(pPosition){
position += pPosition;
self.setPosition(position);
}

this.setPosition = function(pPosition){
position = pPosition;

if(position > maxPosition)
position = maxPosition;
if(position < minPosition)
position = minPosition;

var pos_ = JPos.getAbsPos(oTrackArea);
var w_ = parseInt(getRunStyle(oBtnPointer,"width"));

oBtnPointer.style.left = pos_.x - w_/2 + preFrequenceWidth * position + "px";

doChange();
}

var doChange = function(){
self.onChange(position);
}

this.getPosition = function(){
return position;
}

this.setSkin = function(pSkin){
oOutline.className = pSkin;
recalcTrackArea();
}
}
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