鼠标拖拉按比例缩放的JavaScript_层和布局特效

利用JS写的一个拖拉缩放框，可以设置按比例缩入、像PS软件一样的裁切区域，代码可要费的劲看哦，要不然看不懂的。

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" mrc="text/html; charset=gb2312" />
<title>拖拉缩放效果</title>
</head>
<body>
<script>
var isIE = (document.all) ? true : false;
var $ = function (id) {
 return "string" == typeof id ? document.getElementById(id) : id;
};
var Class = {
 create: function() {
  return function() { this.initialize.apply(this, arguments); }
 }
}
var Extend = function(destination, source) {
 for (var property in source) {
  destination[property] = source[property];
 }
}
var Bind = function(object, fun) {
 return function() {
  return fun.apply(object, arguments);
 }
}
var BindAsEventListener = function(object, fun) {
 var args = Array.prototype.slice.call(arguments).slice(2);
 return function(event) {
  return fun.apply(object, [event || window.event].concat(args));
 }
}
var CurrentStyle = function(element){
 return element.currentStyle || document.defaultView.getComputedStyle(element, null);
}
function addEventHandler(oTarget, sEventType, fnHandler) {
 if (oTarget.addEventListener) {
  oTarget.addEventListener(sEventType, fnHandler, false);
 } else if (oTarget.attachEvent) {
  oTarget.attachEvent("on" + sEventType, fnHandler);
 } else {
  oTarget["on" + sEventType] = fnHandler;
 }
};
function removeEventHandler(oTarget, sEventType, fnHandler) {
    if (oTarget.removeEventListener) {
        oTarget.removeEventListener(sEventType, fnHandler, false);
    } else if (oTarget.detachEvent) {
        oTarget.detachEvent("on" + sEventType, fnHandler);
    } else { 
        oTarget["on" + sEventType] = null;
    }
};
//缩放程序
var Resize = Class.create();
Resize.prototype = {
initialize: function(obj, options) {
 this._obj = $(obj);//缩放对象
 
 this._styleWidth = this._styleHeight = this._styleLeft = this._styleTop = 0;//样式参数
 this._sideRight = this._sideDown = this._sideLeft = this._sideUp = 0;//坐标参数
 this._fixLeft = this._fixTop = 0;//定位参数
 this._scaleLeft = this._scaleTop = 0;//定位坐标
 
 this._mxSet = function(){};//范围设置
 this._mxRightWidth = this._mxDownHeight = this._mxUpHeight = this._mxLeftWidth = 0;//范围参数
 this._mxScaleWidth = this._mxScaleHeight = 0;//比例范围参数
 
 this._fun = function(){};//缩放执行程序
 
 //获取边框宽度
 var _style = CurrentStyle(this._obj);
 this._borderX = (parseInt(_style.borderLeftWidth) || 0) + (parseInt(_style.borderRightWidth) || 0);
 this._borderY = (parseInt(_style.borderTopWidth) || 0) + (parseInt(_style.borderBottomWidth) || 0);
 //事件对象(用于绑定移除事件)
 this._fR = BindAsEventListener(this, this.Resize);
 this._fS = Bind(this, this.Stop);
 
 this.SetOptions(options);
 //范围限制
 this.Max = !!this.options.Max;
 this._mxContainer = $(this.options.mxContainer) || null;
 this.mxLeft = Math.round(this.options.mxLeft);
 this.mxRight = Math.round(this.options.mxRight);
 this.mxTop = Math.round(this.options.mxTop);
 this.mxBottom = Math.round(this.options.mxBottom);
 //宽高限制
 this.Min = !!this.options.Min;
 this.minWidth = Math.round(this.options.minWidth);
 this.minHeight = Math.round(this.options.minHeight);
 //按比例缩放
 this.Scale = !!this.options.Scale;
 this.Ratio = Math.max(this.options.Ratio, 0);
 
 this.onResize = this.options.onResize;
 
 this._obj.style.position = "absolute";
 !this._mxContainer || CurrentStyle(this._mxContainer).position == "relative" || (this._mxContainer.style.position = "relative");
  },
  //设置默认属性
  SetOptions: function(options) {
    this.options = {//默认值
  Max:  false,//是否设置范围限制(为true时下面mx参数有用)
  mxContainer:"",//指定限制在容器内
  mxLeft:  0,//左边限制
  mxRight: 9999,//右边限制
  mxTop:  0,//上边限制
  mxBottom: 9999,//下边限制
  Min:  false,//是否最小宽高限制(为true时下面min参数有用)
  minWidth: 50,//最小宽度
  minHeight: 50,//最小高度
  Scale:  false,//是否按比例缩放
  Ratio:  0,//缩放比例(宽/高)
  onResize: function(){}//缩放时执行
    };
    Extend(this.options, options || {});
  },
  //设置触发对象
  Set: function(resize, side) {
 var resize = $(resize), fun;
 if(!resize) return;
 //根据方向设置
 switch (side.toLowerCase()) {
 case "up" :
  fun = this.Up;
  break;
 case "down" :
  fun = this.Down;
  break;
 case "left" :
  fun = this.Left;
  break;
 case "right" :
  fun = this.Right;
  break;
 case "left-up" :
  fun = this.LeftUp;
  break;
 case "right-up" :
  fun = this.RightUp;
  break;
 case "left-down" :
  fun = this.LeftDown;
  break;
 case "right-down" :
 default :
  fun = this.RightDown;
 };
 //设置触发对象
 addEventHandler(resize, "mousedown", BindAsEventListener(this, this.Start, fun));
  },
  //准备缩放
  Start: function(e, fun, touch) { 
 //防止冒泡(跟拖放配合时设置)
 e.stopPropagation ? e.stopPropagation() : (e.cancelBubble = true);
 //设置执行程序
 this._fun = fun;
 //样式参数值
 this._styleWidth = this._obj.clientWidth;
 this._styleHeight = this._obj.clientHeight;
 this._styleLeft = this._obj.offsetLeft;
 this._styleTop = this._obj.offsetTop;
 //四条边定位坐标
 this._sideLeft = e.clientX - this._styleWidth;
 this._sideRight = e.clientX + this._styleWidth;
 this._sideUp = e.clientY - this._styleHeight;
 this._sideDown = e.clientY + this._styleHeight;
 //top和left定位参数
 this._fixLeft = this._styleLeft + this._styleWidth;
 this._fixTop = this._styleTop + this._styleHeight;
 //缩放比例
 if(this.Scale){
  //设置比例
  this.Ratio = Math.max(this.Ratio, 0) || this._styleWidth / this._styleHeight;
  //left和top的定位坐标
  this._scaleLeft = this._styleLeft + this._styleWidth / 2;
  this._scaleTop = this._styleTop + this._styleHeight / 2;
 };
 //范围限制
 if(this.Max){
  //设置范围参数
  var mxLeft = this.mxLeft, mxRight = this.mxRight, mxTop = this.mxTop, mxBottom = this.mxBottom;
  //如果设置了容器，再修正范围参数
  if(!!this._mxContainer){
   mxLeft = Math.max(mxLeft, 0);
   mxTop = Math.max(mxTop, 0);
   mxRight = Math.min(mxRight, this._mxContainer.clientWidth);
   mxBottom = Math.min(mxBottom, this._mxContainer.clientHeight);
  };
  //根据最小值再修正
  mxRight = Math.max(mxRight, mxLeft + (this.Min ? this.minWidth : 0) + this._borderX);
  mxBottom = Math.max(mxBottom, mxTop + (this.Min ? this.minHeight : 0) + this._borderY);
  //由于转向时要重新设置所以写成function形式
  this._mxSet = function(){
   this._mxRightWidth = mxRight - this._styleLeft - this._borderX;
   this._mxDownHeight = mxBottom - this._styleTop - this._borderY;
   this._mxUpHeight = Math.max(this._fixTop - mxTop, this.Min ? this.minHeight : 0);
   this._mxLeftWidth = Math.max(this._fixLeft - mxLeft, this.Min ? this.minWidth : 0);
  };
  this._mxSet();
  //有缩放比例下的范围限制
  if(this.Scale){
   this._mxScaleWidth = Math.min(this._scaleLeft - mxLeft, mxRight - this._scaleLeft - this._borderX) * 2;
   this._mxScaleHeight = Math.min(this._scaleTop - mxTop, mxBottom - this._scaleTop - this._borderY) * 2;
  };
 };
 //mousemove时缩放 mouseup时停止
 addEventHandler(document, "mousemove", this._fR);
 addEventHandler(document, "mouseup", this._fS);
 if(isIE){
  addEventHandler(this._obj, "losecapture", this._fS);
  this._obj.setCapture();
 }else{
  addEventHandler(window, "blur", this._fS);
  e.preventDefault();
 };
  },
  //缩放
  Resize: function(e) {
 //清除选择
 window.getSelection ? window.getSelection().removeAllRanges() : document.selection.empty();
 //执行缩放程序
 this._fun(e);
 //设置样式，变量必须大于等于0否则ie出错
 with(this._obj.style){
  width = this._styleWidth + "px"; height = this._styleHeight + "px";
  top = this._styleTop + "px"; left = this._styleLeft + "px";
 }
 //附加程序
 this.onResize();
  },
  //缩放程序
  //上
  Up: function(e) {
 this.RepairY(this._sideDown - e.clientY, this._mxUpHeight);
 this.RepairTop();
 this.TurnDown(this.Down);
  },
  //下
  Down: function(e) {
 this.RepairY(e.clientY - this._sideUp, this._mxDownHeight);
 this.TurnUp(this.Up);
  },
  //右
  Right: function(e) {
 this.RepairX(e.clientX - this._sideLeft, this._mxRightWidth);
 this.TurnLeft(this.Left);
  },
  //左
  Left: function(e) {
 this.RepairX(this._sideRight - e.clientX, this._mxLeftWidth);
 this.RepairLeft();
 this.TurnRight(this.Right);
  },
  //右下
  RightDown: function(e) {
 this.RepairAngle(
  e.clientX - this._sideLeft, this._mxRightWidth,
  e.clientY - this._sideUp, this._mxDownHeight
 );
 this.TurnLeft(this.LeftDown) || this.TurnUp(this.RightUp);
  },
  //右上
  RightUp: function(e) {
 this.RepairAngle(
  e.clientX - this._sideLeft, this._mxRightWidth,
  this._sideDown - e.clientY, this._mxUpHeight
 );
 this.RepairTop();
 this.TurnLeft(this.LeftUp) || this.TurnDown(this.RightDown);
  },
  //左下
  LeftDown: function(e) {
 this.RepairAngle(
  this._sideRight - e.clientX, this._mxLeftWidth,
  e.clientY - this._sideUp, this._mxDownHeight
 );
 this.RepairLeft();
 this.TurnRight(this.RightDown) || this.TurnUp(this.LeftUp);
  },
  //左上
  LeftUp: function(e) {
 this.RepairAngle(
  this._sideRight - e.clientX, this._mxLeftWidth,
  this._sideDown - e.clientY, this._mxUpHeight
 );
 this.RepairTop(); this.RepairLeft();
 this.TurnRight(this.RightUp) || this.TurnDown(this.LeftDown);
  },
  //修正程序
  //水平方向
  RepairX: function(iWidth, mxWidth) {
 iWidth = this.RepairWidth(iWidth, mxWidth);
 if(this.Scale){
  var iHeight = Math.round(iWidth / this.Ratio);
  if(this.Max  &&  iHeight > this._mxScaleHeight){
   iWidth = Math.round((iHeight = this._mxScaleHeight) * this.Ratio);
  }else if(this.Min  &&  iHeight < this.minHeight){
   var tWidth = Math.round(this.minHeight * this.Ratio);
   if(tWidth < mxWidth){ iHeight = this.minHeight; iWidth = tWidth; }
  }
  this._styleHeight = iHeight;
  this._styleTop = this._scaleTop - iHeight / 2;
 }
 this._styleWidth = iWidth;
  },
  //垂直方向
  RepairY: function(iHeight, mxHeight) {
 iHeight = this.RepairHeight(iHeight, mxHeight);
 if(this.Scale){
  var iWidth = Math.round(iHeight * this.Ratio);
  if(this.Max  &&  iWidth > this._mxScaleWidth){
   iHeight = Math.round((iWidth = this._mxScaleWidth) / this.Ratio);
  }else if(this.Min  &&  iWidth < this.minWidth){
   var tHeight = Math.round(this.minWidth / this.Ratio);
   if(tHeight < mxHeight){ iWidth = this.minWidth; iHeight = tHeight; }
  }
  this._styleWidth = iWidth;
  this._styleLeft = this._scaleLeft - iWidth / 2;
 }
 this._styleHeight = iHeight;
  },
  //对角方向
  RepairAngle: function(iWidth, mxWidth, iHeight, mxHeight) {
 iWidth = this.RepairWidth(iWidth, mxWidth); 
 if(this.Scale){
  iHeight = Math.round(iWidth / this.Ratio);
  if(this.Max  &&  iHeight > mxHeight){
   iWidth = Math.round((iHeight = mxHeight) * this.Ratio);
  }else if(this.Min  &&  iHeight < this.minHeight){
   var tWidth = Math.round(this.minHeight * this.Ratio);
   if(tWidth < mxWidth){ iHeight = this.minHeight; iWidth = tWidth; }
  }
 }else{
  iHeight = this.RepairHeight(iHeight, mxHeight);
 }
 this._styleWidth = iWidth;
 this._styleHeight = iHeight;
  },
  //top
  RepairTop: function() {
 this._styleTop = this._fixTop - this._styleHeight;
  },
  //left
  RepairLeft: function() {
 this._styleLeft = this._fixLeft - this._styleWidth;
  },
  //height
  RepairHeight: function(iHeight, mxHeight) {
 iHeight = Math.min(this.Max ? mxHeight : iHeight, iHeight);
 iHeight = Math.max(this.Min ? this.minHeight : iHeight, iHeight, 0);
 return iHeight;
  },
  //width
  RepairWidth: function(iWidth, mxWidth) {
 iWidth = Math.min(this.Max ? mxWidth : iWidth, iWidth);
 iWidth = Math.max(this.Min ? this.minWidth : iWidth, iWidth, 0);
 return iWidth;
  },
  //转向程序
  //转右
  TurnRight: function(fun) {
 if(!(this.Min || this._styleWidth)){
  this._fun = fun;
  this._sideLeft = this._sideRight;
  this.Max  &&  this._mxSet();
  return true;
 }
  },
  //转左
  TurnLeft: function(fun) {
 if(!(this.Min || this._styleWidth)){
  this._fun = fun;
  this._sideRight = this._sideLeft;
  this._fixLeft = this._styleLeft;
  this.Max  &&  this._mxSet();
  return true;
 }
  },
  //转上
  TurnUp: function(fun) {
 if(!(this.Min || this._styleHeight)){
  this._fun = fun;
  this._sideDown = this._sideUp;
  this._fixTop = this._styleTop;
  this.Max  &&  this._mxSet();
  return true;
 }
  },
  //转下
  TurnDown: function(fun) {
 if(!(this.Min || this._styleHeight)){
  this._fun = fun;
  this._sideUp = this._sideDown;
  this.Max  &&  this._mxSet();
  return true;
 }
  },
  //停止缩放
  Stop: function() {
 removeEventHandler(document, "mousemove", this._fR);
 removeEventHandler(document, "mouseup", this._fS);
 if(isIE){
  removeEventHandler(this._obj, "losecapture", this._fS);
  this._obj.releaseCapture();
 }else{
  removeEventHandler(window, "blur", this._fS);
 }
  }
};
</script>
<script type="text/javascript" src="http://files.cnblogs.com/cloudgamer/Drag.js"></script>
<style type="text/css">
#rRightDown,#rLeftDown,#rLeftUp,#rRightUp,#rRight,#rLeft,#rUp,#rDown{
 position:absolute;
 background:#C00;
 width:7px;
 height:7px;
 z-index:5;
 font-size:0;
}
#rLeftDown,#rRightUp{cursor:ne-resize;}
#rRightDown,#rLeftUp{cursor:nw-resize;}
#rRight,#rLeft{cursor:e-resize;}
#rUp,#rDown{cursor:n-resize;}
#rLeftDown{left:-4px;bottom:-4px;}
#rRightUp{right:-4px;top:-4px;}
#rRightDown{right:-4px;bottom:-4px;background-color:#00F;}
#rLeftUp{left:-4px;top:-4px;}
#rRight{right:-4px;top:50%;margin-top:-4px;}
#rLeft{left:-4px;top:50%;margin-top:-4px;}
#rUp{top:-4px;left:50%;margin-left:-4px;}
#rDown{bottom:-4px;left:50%;margin-left:-4px;}
#bgDiv{width:600px; height:300px; border:10px solid #666666; position:relative;}
#dragDiv{border:1px solid #000000; width:100px; height:60px; top:50px; left:50px; background:#fff;}
</style>
<div id="bgDiv">
  <div id="dragDiv">
    <div id="rRightDown"> </div>
    <div id="rLeftDown"> </div>
    <div id="rRightUp"> </div>
    <div id="rLeftUp"> </div>
    <div id="rRight"> </div>
    <div id="rLeft"> </div>
    <div id="rUp"> </div>
    <div id="rDown"></div>
  </div>
</div>
<div>
<input id="idScale" type="button" value="设置比例" />
<input id="idMin" type="button" value="设置最小范围" />
</div>
<script>
var rs = new Resize("dragDiv", { Max: true, mxContainer: "bgDiv" });
rs.Set("rRightDown", "right-down");
rs.Set("rLeftDown", "left-down");
rs.Set("rRightUp", "right-up");
rs.Set("rLeftUp", "left-up");
rs.Set("rRight", "right");
rs.Set("rLeft", "left");
rs.Set("rUp", "up");
rs.Set("rDown", "down");
$("idScale").onclick = function(){
 if(rs.Scale){
  this.value = "设置比例";
  rs.Scale = false;
 }else{
  this.value = "取消比例";
  rs.Scale = true;
 }
}
$("idMin").onclick = function(){
 if(rs.Min){
  this.value = "设置最小范围";
  rs.Min = false;
 }else{
  this.value = "取消最小范围";
  rs.Min = true;
 }
}
new Drag("dragDiv", { Limit: true, mxContainer: "bgDiv" });
</script>
</body>
</html>

所属频道：层和布局特效/更新时间：2012-12-28

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