本文實例講述了JS基于面向對象實現的拖拽庫。分享給大家供大家參考。具體如下：
這是一個面向對象的JS拖拽庫，可設置水平鎖定、垂直鎖定、鎖定位置、鎖定范圍等，設定這些范圍后，只能在設定的模式下拖動，我覺得這是個挺不錯的拖拽實例。
運行效果截圖如下：
在線演示地址如下：
http://demo.VeVB.COm/js/2015/js-mxdx-draw-plug-codes/
具體代碼如下：
<!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" content="text/html; charset=utf-8" /><title>拖拽庫</title><style type="text/css"> div,h2,p{margin:0;padding:0;}body{font:14px/1.5 arial;}#box{width:100px;height:100px;background:#fef4eb;padding:5px;margin:50px;border:1px solid #f60;}#box .title{height:25px;background:#f60;}#tool{margin-bottom:10px;}</style><script type="text/javascript"> function Drag(){ //初始化 this.initialize.apply(this, arguments)}Drag.prototype = { //初始化 initialize : function (drag, options) { this.drag = this.$(drag); this._x = this._y = 0; this._moveDrag = this.bind(this, this.moveDrag); this._stopDrag = this.bind(this, this.stopDrag); this.setOptions(options); this.handle = this.$(this.options.handle); this.maxContainer = this.$(this.options.maxContainer); this.maxTop = Math.max(this.maxContainer.clientHeight, this.maxContainer.scrollHeight) - this.drag.offsetHeight; this.maxLeft = Math.max(this.maxContainer.clientWidth, this.maxContainer.scrollWidth) - this.drag.offsetWidth; this.limit = this.options.limit; this.lockX = this.options.lockX; this.lockY = this.options.lockY; this.lock = this.options.lock; this.onStart = this.options.onStart; this.onMove = this.options.onMove; this.onStop = this.options.onStop; this.handle.style.cursor = "move"; this.changeLayout(); this.addHandler(this.handle, "mousedown", this.bind(this, this.startDrag)) }, changeLayout : function () { this.drag.style.top = this.drag.offsetTop + "px"; this.drag.style.left = this.drag.offsetLeft + "px"; this.drag.style.position = "absolute"; this.drag.style.margin = "0" }, startDrag : function (event) { var event = event || window.event; this._x = event.clientX - this.drag.offsetLeft; this._y = event.clientY - this.drag.offsetTop; this.addHandler(document, "mousemove", this._moveDrag); this.addHandler(document, "mouseup", this._stopDrag); event.preventDefault && event.preventDefault(); this.handle.setCapture && this.handle.setCapture(); this.onStart() }, moveDrag : function (event) { var event = event || window.event; var iTop = event.clientY - this._y; var iLeft = event.clientX - this._x; if (this.lock) return; this.limit && (iTop < 0 && (iTop = 0), iLeft < 0 && (iLeft = 0), iTop > this.maxTop && (iTop = this.maxTop), iLeft > this.maxLeft && (iLeft = this.maxLeft)); this.lockY || (this.drag.style.top = iTop + "px"); this.lockX || (this.drag.style.left = iLeft + "px"); event.preventDefault && event.preventDefault(); this.onMove() }, stopDrag : function () { this.removeHandler(document, "mousemove", this._moveDrag); this.removeHandler(document, "mouseup", this._stopDrag); this.handle.releaseCapture && this.handle.releaseCapture(); this.onStop() }, //參數設置 setOptions : function (options) { this.options = { handle: this.drag, //事件對象 limit: true, //鎖定范圍 lock: false, //鎖定位置 lockX: false, //鎖定水平位置 lockY: false, //鎖定垂直位置 maxContainer: document.documentElement || document.body, //指定限制容器 onStart: function () {}, //開始時回調函數 onMove: function () {}, //拖拽時回調函數 onStop: function () {} //停止時回調函數 }; for (var p in options) this.options[p] = options[p] }, //獲取id $ : function (id) { return typeof id === "string" ? document.getElementById(id) : id }, //添加綁定事件 addHandler : function (oElement, sEventType, fnHandler) { return oElement.addEventListener ? oElement.addEventListener(sEventType, fnHandler, false) : oElement.attachEvent("on" + sEventType, fnHandler) }, //刪除綁定事件 removeHandler : function (oElement, sEventType, fnHandler) { return oElement.removeEventListener ? oElement.removeEventListener(sEventType, fnHandler, false) : oElement.detachEvent("on" + sEventType, fnHandler) }, //綁定事件到對象 bind : function (object, fnHandler) { return function () { return fnHandler.apply(object, arguments) } }};//應用window.onload = function (){ var oBox = document.getElementById("box"); var oTitle = oBox.getElementsByTagName("h2")[0]; var oSpan = document.getElementsByTagName("span")[0]; var oDrag = new Drag(oBox, {handle:oTitle, limit:false}); var aInput = document.getElementsByTagName("input"); //鎖定范圍接口 aInput[0].onclick = function () { oDrag.limit = !oDrag.limit; this.value = oDrag.limit ? "取消鎖定范圍" : "鎖定范圍" }; //水平鎖定接口 aInput[1].onclick = function () { oDrag.lockX = !oDrag.lockX; this.value = oDrag.lockX ? "取消水平鎖定" : "水平鎖定" }; //垂直鎖定接口 aInput[2].onclick = function () { oDrag.lockY = !oDrag.lockY; this.value = oDrag.lockY ? "取消垂直鎖定" : "垂直鎖定" }; //鎖定位置接口 aInput[3].onclick = function () { oDrag.lock = !oDrag.lock; this.value = oDrag.lock ? "取消鎖定位置" : "鎖定位置" }; //開始拖拽時方法 oDrag.onStart = function () { oSpan.innerHTML = "開始拖拽" }; //開始拖拽時方法 oDrag.onMove = function () { oSpan.innerHTML = "left:" + this.drag.offsetLeft + ", top:" + this.drag.offsetTop }; //開始拖拽時方法 oDrag.onStop = function () { oSpan.innerHTML = "結束拖拽" };};</script></head><body><div id="tool"><input type="button" value="鎖定范圍" /> <input type="button" value="水平鎖定" /> <input type="button" value="垂直鎖定" /> <input type="button" value="鎖定位置" /></div><p>拖放狀態：<span>未開始</span></p><div id="box"> <h2 class="title"></h2></div></body></html>希望本文所述對大家的JavaScript程序設計有所幫助。
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