需求背景：
物联网项目，需要在地图上展示设备的位置，能够对地图进行拖拽，缩放，点击设备能够展示出设备的信息。
本代码实现了图片的缩放，拖拽，点击图片显示鼠标指针所处位置的坐标（相对于图片）。
<!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" lang="utf-8">
<head>
<title></title>
<meta http-equiv="content-type" content="text/html; charset=utf-8" />
<style>
.dragAble {
position: relative;
cursor: move;
}
</style>
<script language="javascript">
//放大缩小
window.onload = function() {
var oImg = document.getElementsByTagName("img")[0];
function fnWheel(obj, fncc) {
obj.onmousewheel = fn;
if (obj.addEventListener) {
obj.addEventListener('DOMMouseScroll', fn, false);
}
function fn(ev) {
var oEvent = ev || window.event;
var down = true;
if (oEvent.detail) {
down = oEvent.detail > 0
} else {
down = oEvent.wheelDelta < 0
}
if (fncc) {
fncc.call(this, down, oEvent);
}
if (oEvent.preventDefault) {
oEvent.preventDefault();
}
return false;
}
};
fnWheel(oImg, function(down, oEvent) {
var oldWidth = this.offsetWidth;
var oldHeight = this.offsetHeight;
var oldLeft = this.offsetLeft;
var oldTop = this.offsetTop;
var scaleX = (oEvent.clientX - oldLeft) / oldWidth; //比例
var scaleY = (oEvent.clientY - oldTop) / oldHeight;
if (down) {
this.style.width = this.offsetWidth * 0.9 + "px";
this.style.height = this.offsetHeight * 0.9 + "px";
} else {
this.style.width = this.offsetWidth * 1.1 + "px";
this.style.height = this.offsetHeight * 1.1 + "px";
}
var newWidth = this.offsetWidth;
var newHeight = this.offsetHeight;
this.style.left = oldLeft - scaleX * (newWidth - oldWidth) + "px";
this.style.top = oldTop - scaleY * (newHeight - oldHeight) + "px";
});
}
<!--
//拖拽
var ie = document.all;
var nn6 = document.getElementByIdx && !document.all;
var isdrag = false;
var y, x;
var oDragObj;
function moveMouse(e) {
if (isdrag) {
oDragObj.style.top = (nn6 ? nTY + e.clientY - y : nTY + event.clientY - y) + "px";
oDragObj.style.left = (nn6 ? nTX + e.clientX - x : nTX + event.clientX - x) + "px";
return false;
}
}
function initDrag(e) {
var oDragHandle = nn6 ? e.target : event.srcElement;
var topElement = "HTML";
while (oDragHandle.tagName != topElement && oDragHandle.className != "dragAble") {
oDragHandle = nn6 ? oDragHandle.parentNode : oDragHandle.parentElement;
}
if (oDragHandle.className == "dragAble") {
isdrag = true;
oDragObj = oDragHandle;
nTY = parseInt(oDragObj.style.top + 0);
y = nn6 ? e.clientY : event.clientY;
nTX = parseInt(oDragObj.style.left + 0);
x = nn6 ? e.clientX : event.clientX;
document.onmousemove = moveMouse;
return false;
}
}
document.onmousedown = initDrag;
document.onmouseup = new Function("isdrag=false");
//-->
</script>
</head>
<body>
<img id="monitor_map" src="bg.jpg" class="dragAble" style="margin:0;padding: 0" onclick="mapOnClick(event)" />
</body>
<script src="http://libs.baidu.com/jquery/2.0.0/jquery.min.js"></script>
<script>
function mapOnClick(e) {
e = e || window.event;
var imgId = '#' + $(e.target).attr('id');
var currentWidth = $(imgId).width();
var currentHeight = $(imgId).height();
var offsetX = e.pageX - $(imgId).offset().left;
var offsetY = e.pageY - $(imgId).offset().top;
var x = offsetX / currentWidth;
var y = offsetY / currentHeight;
alert(x + ':' + y)
}
</script>
</html>
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