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面向对象继承-限制范围的拖拽

2017-03-22 17:55 190 查看

<!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=gb2312" />
<title>无标题文档</title>
<style>
div{width:100px;height:100px;background:red;position:absolute;}
#pox{background:blue;left:200px;}
</style>
<script>

window.onload = function () {

var d1 = new Drag('box');
d1.init();

var d2 = new LimitRangeDrag('pox');
d2.init();

}
function Drag(id) {

this.oBox = document.getElementById(id);
this.disX = 0;
this.disY = 0;

}
Drag.prototype.init = function() {
var _this = this;
this.oBox.onmousedown = function (ev) {
var ev = ev || window.event;
_this.fnDown(ev);

return false;
};
}
Drag.prototype.fnDown = function (ev) {

this.disX = ev.clientX - this.oBox.offsetLeft;
this.disY = ev.clientY - this.oBox.offsetTop;
var _this = this;

document.onmousemove = function (ev){
var ev = ev || window.event;
_this.fnMove(ev);
};

document.onmouseup = function () {
_this.fnUp();
};
}

Drag.prototype.fnMove = function (ev) {

this.oBox.style.left = ev.clientX - this.disX + 'px';
this.oBox.style.top = ev.clientY - this.disY + 'px';

}
Drag.prototype.fnUp = function () {
document.onmousemove = document.onmousedown = null;
}

// 限制范围的拖拽
function LimitRangeDrag(id) {
// 继承属性
Drag.call(this, id);
}
// for in 拷贝继承
copy(LimitRangeDrag.prototype, Drag.prototype);

function copy(child, parent) {
for ( var attr in parent ) {
child[attr] = parent[attr];
}
}
// 现在范围
LimitRangeDrag.prototype.fnMove = function (ev) {

var L = ev.clientX - this.disX;
var T = ev.clientY - this.disY;

if(T > document.documentElement.clientHeight - this.oBox.offsetHeight){
T = document.documentElement.clientHeight - this.oBox.offsetHeight;
} else if ( T < 0 ) {
T = 0;
}
if(L > document.documentElement.clientWidth - this.oBox.offsetWidth){
L = document.documentElement.clientWidth - this.oBox.offsetWidth;
} else if ( L < 0 ) {
L = 0;
}
this.oBox.style.left = L + 'px';
this.oBox.style.top = T + 'px';

}

</script>
</head>

<body>
<div id="box"></div>
<div id="pox"></div>
</body>
</html>

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标签： 面向对象继承拖拽限制范围的拖拽

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