javascript实现鼠标拖动改变层大小的方法

本文实例讲述了javascript实现鼠标拖动改变层大小的方法。分享给大家供大家参考。具体实现方法如下：

<html>
<head>
<title>拖动改变层的大小</title>
<meta content="text/html; charset=gb2312" http-equiv="Content-Type">
<style> {
box-sizing: border-box; moz-box-sizing: border-box
}
#testDiv { background-color: buttonface; background-repeat: repeat;
background-attachment: scroll; color: #3969A5; height: 300px;
left: 30px; overflow: hidden; width: 500; z-index: 2;
border: 2px outset white; margin: 0px; padding: 2px;
background-position: 0% 50% }
body { font-family: Verdana; font-size: 9pt }
#innerNice { background-color: white; background-repeat: repeat;
background-attachment:
scroll; color: #3969A5; height: 100%; overflow: auto;
width: 100%; border: 2px inset white; padding: 8px;
background-position: 0% 50% }
</style>
<SCRIPT language=javascript>
var theobject = null;
function resizeObject() {
this.el = null; //pointer to the object
this.dir = ""; //type of current resize (n,s,e,w,ne,nw,se,sw)
this.grabx = null; //Some useful values
this.graby = null;
this.width = null;
this.height = null;
this.left = null;
this.top = null;
}
function getDirection(el) {
var xPos, yPos, offset, dir;
dir = "";
xPos = window.event.offsetX;
yPos = window.event.offsetY;
offset = 8; //The distance from the edge in pixels
if (yPos<offset) dir += "n";
else if (yPos > el.offsetHeight-offset) dir += "s";
if (xPos<offset) dir += "w";
else if (xPos > el.offsetWidth-offset) dir += "e";
return dir;
}
function doDown() {
var el = getReal(event.srcElement, "className", "resizeMe");
if (el == null) {
theobject = null;
return;
}
dir = getDirection(el);
if (dir == "") return;
theobject = new resizeObject();
theobject.el = el;
theobject.dir = dir;
theobject.grabx = window.event.clientX;
theobject.graby = window.event.clientY;
theobject.width = el.offsetWidth;
theobject.height = el.offsetHeight;
theobject.left = el.offsetLeft;
theobject.top = el.offsetTop;
window.event.returnValue = false;
window.event.cancelBubble = true;
}
function doUp() {
if (theobject != null) {
theobject = null;
}
}
function doMove() {
var el, xPos, yPos, str, xMin, yMin;
xMin = 8; //The smallest width possible
yMin = 8; // height
el = getReal(event.srcElement, "className", "resizeMe");
if (el.className == "resizeMe") {
str = getDirection(el);
//Fix the cursor
if (str == "") str = "default";
else str += "-resize";
el.style.cursor = str;
}
//Dragging starts here
if(theobject != null) {
if (dir.indexOf("e") != -1)
theobject.el.style.width = Math.max(xMin, theobject.width + window.event.clientX - theobject.grabx) + "px";
if (dir.indexOf("s") != -1)
theobject.el.style.height = Math.max(yMin, theobject.height + window.event.clientY - theobject.graby) + "px";
if (dir.indexOf("w") != -1) {
theobject.el.style.left = Math.min(theobject.left + window.event.clientX - theobject.grabx, theobject.left + theobject.width - xMin) + "px";
theobject.el.style.width = Math.max(xMin, theobject.width - window.event.clientX + theobject.grabx) + "px";
}
if (dir.indexOf("n") != -1) {
theobject.el.style.top = Math.min(theobject.top + window.event.clientY - theobject.graby, theobject.top + theobject.height - yMin) + "px";
theobject.el.style.height = Math.max(yMin, theobject.height - window.event.clientY + theobject.graby) + "px";
}
window.event.returnValue = false;
window.event.cancelBubble = true;
}
}
function getReal(el, type, value) {
temp = el;
while ((temp != null) && (temp.tagName != "BODY")) {
if (eval("temp." + type) == value) {
el = temp;
return el;
}
temp = temp.parentElement;
}
return el;
}
document.onmousedown = doDown;
document.onmouseup = doUp;
document.onmousemove = doMove;
</SCRIPT>
</head>
<body>
<div class="resizeMe" id="testDiv">
<div id="innerNice">
<p align="center">　</p>
<p align="center">
请在边框处拖动鼠标</p>
<p>　</p>
<p>　</p>
<p>　</p>
</div>
</div>
</body>
</html>

希望本文所述对大家的javascript程序设计有所帮助。