1. 全栈程序员必看首页

鼠标捕获(setCapture，releaseCapture)的学习

全栈程序员-用户IM • • 未分类

鼠标捕获(setCapture，releaseCapture)的学习鼠标捕获(setCapture)作用是将鼠标事件捕获到当前文档的指定的对象——对指定的对象设置鼠标捕获。这个对象会为当前应用程序或整个系统接收所有鼠标事件。所谓鼠标捕获，是指对鼠标事件（onmousedown,onmouseup,onmousemove,onclick,ondblclick,onmouseover,onmouseout）进行捕捉，使在容器内的子对象的鼠标事件均…

大家好，又见面了，我是你们的朋友全栈君。

鼠标捕获(setCapture)作用是将鼠标事件捕获到当前文档的指定的对象——对指定的对象设置鼠标捕获。这个对象会为当前应用程序或整个系统接收所有鼠标事件。

  • 所谓鼠标捕获，是指对鼠标事件（onmousedown, onmouseup, onmousemove, onclick, ondblclick, onmouseover, onmouseout）进行捕捉，使在容器内的子对象的鼠标事件均由容器对象触发，因此，只能在容器对象的鼠标事件函数中进行处理。
  • 当参数为true时，对鼠标进行捕捉，相反，不捕捉。
  • 与这个函数对应，releaseCapture方法释放鼠标捕获，并触发onlosecapture事件。

一、语法

1. MDN(Mozilla Developer Network)

element.setCapture(retargetToElement);

retargetToElement——If true, all events are targeted directly to this element; if false, events can also fire at descendants of this element.

document.releaseCapture()

释放鼠标捕捉——Once mouse capture is released, mouse events will no longer all be directed to the element on which capture is enabled.

2. msdn（Internet Explorer Dev Center）

object.setCapture(containerCapture)

其中： containerCapture [in, optional]—— Type:
Boolean

  • true (true)——Default. 容器会捕获容器内所有对象的鼠标事件，即容器内的对象不会触发鼠标事件（跟容器外的对象一样）Events originating in a container are captured by the container.
  • false (false)——容器不会捕获容器内对象的鼠标事件，即容器内的对象可以正常地触发事件和取消冒泡。Events originating in a container are not captured by the container.

　　object.setCapture() 当一个object的被 setCapture 后，他的方法将会被继承到整个文档进行捕获。当不需要把方法继承到整个文档捕获时，要用 object.releaseCapture() 来释放.

二、案例——简单拖拽

完整代码

<!DOCTYPE html> <html> <head> <title>drag example</title> <meta http-equiv="Content-Type" content="text/html;charset=UTF-8"/> <style type="text/css"> #drag{ position:absolute;left:12px;top:24px;width:100px;height:150px; display:block;border:1px solid #000000;z-index:1;background:#eeeeee; cursor: pointer;} </style> </head> <body> <div id="drag">drag me</div> <script type="text/javascript"> window.onload=function(){ objDiv = document.getElementById("drag"); drag(objDiv); }; function drag(dv){ dv.onmousedown=function(e){ var d=document; e = e || window.event; var x= e.layerX || e.offsetX; var y= e.layerY || e.offsetY; //设置捕获范围 if(dv.setCapture){ dv.setCapture(); }else if(window.captureEvents){ window.captureEvents(Event.MOUSEMOVE | Event.MOUSEUP); } d.onmousemove=function(e){ e= e || window.event; if(!e.pageX)e.pageX=e.clientX; if(!e.pageY)e.pageY=e.clientY; document.getElementById("drag").innerHTML= e.pageX+ e.pageY; var tx=e.pageX-x; var ty=e.pageY-y; dv.style.left=tx+"px"; dv.style.top=ty+"px"; }; d.onmouseup=function(){ //取消捕获范围 if(dv.releaseCapture){ dv.releaseCapture(); }else if(window.captureEvents){ window.captureEvents(Event.MOUSEMOVE|Event.MOUSEUP); } //清除事件  d.onmousemove=null; d.onmouseup=null; }; }; } </script> </body> </html>

三、案例——完美拖拽

完整代码

鼠标捕获(setCapture，releaseCapture)的学习
鼠标捕获(setCapture，releaseCapture)的学习 

<!DOCTYPE html> <html> <head> <meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> <title>完美拖拽</title> <style type="text/css"> html,body{ overflow:hidden;} body,div,h2,p{ margin:0;padding:0;} body{ color:#fff;background:#000;font:12px/2 Arial;} p{ padding:0 10px;margin-top:10px;} span{ color:#ff0;padding-left:5px;} #box{ position:absolute;width:300px;height:150px;background:#333;border:2px solid #ccc;top:50%;left:50%;margin:-75px 0 0 -150px;} #box h2{ height:25px;cursor:move;background:#222;border-bottom:2px solid #ccc;text-align:right;padding:0 10px;} #box h2 a{ color:#fff;font:12px/25px Arial;text-decoration:none;outline:none;} </style> <script type="text/javascript"> window.onload=function (){ var oBox=document.getElementById("box"); var oH2 = oBox.getElementsByTagName("h2")[0]; var oA = oBox.getElementsByTagName("a")[0]; var aSpan = oBox.getElementsByTagName("span"); var disX = disY = 0; var bDrag = false; var aPos = [{x:oBox.offsetLeft, y:oBox.offsetTop}]; //鼠标按下, 激活拖拽  oH2.onmousedown = function (event){ var event = event || window.event; bDrag = true; disX = event.clientX - oBox.offsetLeft; disY = event.clientY - oBox.offsetTop; aPos.push({x:oBox.offsetLeft, y:oBox.offsetTop}) this.setCapture && this.setCapture(); return false; }; //拖拽开始  document.onmousemove = function (event){ if (!bDrag) return; var event = event || window.event; var iL = event.clientX - disX; var iT = event.clientY - disY; var maxL = document.documentElement.clientWidth - oBox.offsetWidth; var maxT = document.documentElement.clientHeight - oBox.offsetHeight; iL = iL < 0 ? 0 : iL; iL = iL > maxL ? maxL : iL; iT = iT < 0 ? 0 : iT; iT = iT > maxT ? maxT : iT; oBox.style.marginTop = oBox.style.marginLeft = 0; oBox.style.left = iL + "px"; oBox.style.top = iT + "px"; aPos.push({x:iL, y:iT}) status(); return false; }; //鼠标释放, 结束拖拽  document.onmouseup = window.onblur = oH2.onlosecapture = function (){ bDrag = false; oH2.releaseCapture && oH2.releaseCapture(); status(); }; //回放拖动轨迹  oA.onclick = function (){ if (aPos.length == 1) return; var timer = setInterval(function () { var oPos = aPos.pop(); oPos ? (oBox.style.left = oPos.x + "px", oBox.style.top = oPos.y + "px", status()) : clearInterval(timer) }, 30); this.focus = false;//去除链接虚线  return false; }; //阻止冒泡  oA.onmousedown = function (event){ (event || window.event).cancelBubble = true }; //监听状态函数 function status (){ aSpan[0].innerHTML = bDrag; aSpan[1].innerHTML = oBox.offsetTop; aSpan[2].innerHTML = oBox.offsetLeft; } //初始调用  status(); }; </script> </head> <body> <div id="box"> <h2><a href="javascript:;">点击回放拖动轨迹</a></h2> <p><strong>Drag:</strong><span></span></p> <p><strong>offsetTop:</strong><span></span></p> <p><strong>offsetLeft:</strong><span></span></p> </div> </body> </html>

View Code

javascript代码

//鼠标按下, 激活拖拽 oH2.onmousedown = function (event){ var event = event || window.event; bDrag = true; disX = event.clientX - oBox.offsetLeft; disY = event.clientY - oBox.offsetTop; aPos.push({x:oBox.offsetLeft, y:oBox.offsetTop})； this.setCapture && this.setCapture(); return false; }; //拖拽开始 document.onmousemove = function (event){ if (!bDrag) return; var event = event || window.event; var iL = event.clientX - disX; var iT = event.clientY - disY; var maxL = document.documentElement.clientWidth - oBox.offsetWidth; var maxT = document.documentElement.clientHeight - oBox.offsetHeight; iL = iL < 0 ? 0 : iL; iL = iL > maxL ? maxL : iL; iT = iT < 0 ? 0 : iT; iT = iT > maxT ? maxT : iT; oBox.style.marginTop = oBox.style.marginLeft = 0; oBox.style.left = iL + "px"; oBox.style.top = iT + "px"; aPos.push({x:iL, y:iT}) status(); return false; }; //鼠标释放, 结束拖拽 document.onmouseup = window.onblur = oH2.onlosecapture = function (){ bDrag = false; oH2.releaseCapture && oH2.releaseCapture(); status(); }; //阻止冒泡 oA.onmousedown = function (event){ (event || window.event).cancelBubble = true }; //监听状态函数 function status (){ aSpan[0].innerHTML = bDrag; aSpan[1].innerHTML = oBox.offsetTop; aSpan[2].innerHTML = oBox.offsetLeft; }

参考：

  • https://developer.mozilla.org/en-US/docs/Web/API/Element.setCapture
  • http://msdn.microsoft.com/en-us/library/ie/ms536742%28v=vs.85%29.aspx
版权声明：本文内容由互联网用户自发贡献，该文观点仅代表作者本人。本站仅提供信息存储空间服务，不拥有所有权，不承担相关法律责任。如发现本站有涉嫌侵权/违法违规的内容， 请发送邮件至 举报，一经查实，本站将立刻删除。

发布者：全栈程序员-用户IM，转载请注明出处：https://javaforall.cn/135014.html原文链接：https://javaforall.cn

【正版授权，激活自己账号】： Jetbrains全家桶Ide使用，1年售后保障，每天仅需1毛

【官方授权 正版激活】： 官方授权 正版激活 支持Jetbrains家族下所有IDE 使用个人JB账号...

赞 (0)
全栈程序员-用户IM全栈程序员-用户IM
0 0
blank

相关推荐

发表回复

您的电子邮箱地址不会被公开。

关注全栈程序员社区公众号