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HTML－－如何实现通过鼠标事件拖动页面图像(代码)

2007-08-09 15:39 961 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><title>onMouseMove Event Handler</title>
<style type="text/css">
    #camap {position:absolute; left:20; top:120}
    #ormap {position:absolute; left:80; top:120}
    #wamap {position:absolute; left:140; top:120}
</style>
</head>

<script type="text/javascript">
// global variables used while dragging
var offsetX = 0
var offsetY = 0
var selectedObj
var frontObj
// set document-level event handlers
document.onmousedown = engage
document.onmouseup = release
// positioning an object at a specific pixel coordinate
function shiftTo(obj, x, y) {
    obj.style.pixelLeft = x
    obj.style.pixelTop = y
}
// setting the z-order of an object
function bringToFront(obj) {
    if (frontObj) {
        frontObj.style.zIndex = 0
    }
    frontObj = obj
    frontObj.style.zIndex = 1
}
// set global var to a reference to dragged element
function setSelectedObj() {
    var imgObj = window.event.srcElement
    if (imgObj.id.indexOf("map") == 2) {
        selectedObj = imgObj
        bringToFront(selectedObj)
        return
    }
    selectedObj = null
    return
}
// do the dragging (called repeatedly by onMouseMove)
function dragIt() {
    if (selectedObj) {
        shiftTo(selectedObj, (event.clientX - offsetX), (event.clientY - offsetY))
        return false
    }
}
// set global vars and turn on mousemove trapping (called by onMouseDown)
function engage() {
    setSelectedObj()
    if (selectedObj) {
        document.onmousemove = dragIt
        offsetX = window.event.offsetX - document.body.scrollLeft
        offsetY = window.event.offsetY - document.body.scrollTop
    }
}
// restore everything as before (called by onMouseUp)
function release() {
    if (selectedObj) {
        document.onmousemove = null
        selectedObj = null
    }
}
</script>

<body>
<h1>onMouseMove Event Handler</h1>
<img id="camap" src="d:/bw/n001387.jpg" style="left: 31px; top: 1px" />
<br />
<img id="ormap" src="d:/bw/n001387.jpg" style="left: 31px; top: 297px" />
<br />
<img id="wamap" src="d:/bw/n001387.jpg" style="left: 31px; top: 184px" />
<br />
</body>
</html>

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标签： html function variables reference xhtml object

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