JavaScript method to implement mouse dragging to change layer size

JavaScript method to implement mouse dragging to change layer size_javascript skills

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Release： 2016-05-16 16:01:34

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The example in this article describes the method of using JavaScript to change the layer size by dragging the mouse. Share it with everyone for your reference. The specific implementation method is as follows:

<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>

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I hope this article will be helpful to everyone’s JavaScript programming design.