网页上拖动图片的效果与代码

与上篇JS漂浮广告一文中引用的对象一样,只是JS代码不同

 

self.onError=null; 
    currentX = currentY = 0;  
    whichIt = null;  
    lastScrollX = 0; lastScrollY = 0; 
    NS = (document.layers) ? 1 : 0; 
    IE = (document.all) ? 1: 0; 
    <!-- STALKER CODE --> 
    function heartBeat() { 
        if(IE) { diffY = document.body.scrollTop; diffX = document.body.scrollLeft; } //设置或获取位于对象最顶端和窗口中可见内容的最顶端之间的距离
        if(NS) { diffY = self.pageYOffset; diffX = self.pageXOffset; } 
        if(diffY != lastScrollY) {                        //获取左顶点坐标
       percent = .1 * (diffY - lastScrollY); 
       if(percent > 0) percent = Math.ceil(percent); //返回与某数相等,或大于该数的最小整数
       else percent = Math.floor(percent); 
       if(IE) document.all.floater.style.pixelTop += percent; 
       if(NS) document.floater.top += percent;  
       lastScrollY = lastScrollY + percent; 
     } 
        if(diffX != lastScrollX) { 
            percent = .1 * (diffX - lastScrollX); 
            if(percent > 0) percent = Math.ceil(percent); 
            else percent = Math.floor(percent); 
            if(IE) document.all.floater.style.pixelLeft += percent; 
            if(NS) document.floater.left += percent; 
            lastScrollX = lastScrollX + percent; 
        }     
    } 
    <!-- /STALKER CODE --> 
    <!-- DRAG DROP CODE --> 
    function checkFocus(x,y) {  
    stalkerx = document.floater.pageX; 
    stalkery = document.floater.pageY; 
    stalkerwidth = document.floater.clip.width; 
    stalkerheight = document.floater.clip.height; 
    if( (x > stalkerx && x < (stalkerx+stalkerwidth)) && (y > stalkery && y < (stalkery+stalkerheight))) return true; 
    else return false; 
    } 
    function grabIt(e) { 
        if(IE) { 
            whichIt = event.srcElement;    //查找事件对象
            while (whichIt.id.indexOf("floater") == -1) { 
                whichIt = whichIt.parentElement; 
                if (whichIt == null) { return true; } 
             } 
        whichIt.style.pixelLeft = whichIt.offsetLeft; 
        whichIt.style.pixelTop = whichIt.offsetTop; 
        currentX = (event.clientX + document.body.scrollLeft); 
        currentY = (event.clientY + document.body.scrollTop);      
        } else {  
        window.captureEvents(Event.MOUSEMOVE); 
        if(checkFocus (e.pageX,e.pageY)) {  
        whichIt = document.floater; 
        StalkerTouchedX = e.pageX-document.floater.pageX; 
        StalkerTouchedY = e.pageY-document.floater.pageY; 
        }  
        } 
    return true; 
} 
    function moveIt(e) { 
        if (whichIt == null) { return false; } 
        if(IE) { 
        newX = (event.clientX + document.body.scrollLeft); 
        newY = (event.clientY + document.body.scrollTop); 
        distanceX = (newX - currentX); distanceY = (newY - currentY); 
        currentX = newX; currentY = newY; 
        whichIt.style.pixelLeft += distanceX; 
        whichIt.style.pixelTop += distanceY; 
            if(whichIt.style.pixelTop < document.body.scrollTop) whichIt.style.pixelTop = document.body.scrollTop; 
            if(whichIt.style.pixelLeft < document.body.scrollLeft) whichIt.style.pixelLeft = document.body.scrollLeft; 
            if(whichIt.style.pixelLeft > document.body.offsetWidth - document.body.scrollLeft - whichIt.style.pixelWidth - 20) whichIt.style.pixelLeft = document.body.offsetWidth - whichIt.style.pixelWidth - 20; 
            if(whichIt.style.pixelTop > document.body.offsetHeight + document.body.scrollTop - whichIt.style.pixelHeight - 5) whichIt.style.pixelTop = document.body.offsetHeight + document.body.scrollTop - whichIt.style.pixelHeight - 5; 
            event.returnValue = false; 
        } else {  
            whichIt.moveTo(e.pageX-StalkerTouchedX,e.pageY-StalkerTouchedY); 
    if(whichIt.left < 0+self.pageXOffset) whichIt.left = 0+self.pageXOffset; 
    if(whichIt.top < 0+self.pageYOffset) whichIt.top = 0+self.pageYOffset; 
    if( (whichIt.left + whichIt.clip.width) >= (window.innerWidth+self.pageXOffset-17)) whichIt.left = ((window.innerWidth+self.pageXOffset)-whichIt.clip.width)-17; 
    if( (whichIt.top + whichIt.clip.height) >= (window.innerHeight+self.pageYOffset-17)) whichIt.top = ((window.innerHeight+self.pageYOffset)-whichIt.clip.height)-17; 
    return false; 
        } 
    return false; 
    } 
    function dropIt() { 
        whichIt = null; 
    if(NS) window.releaseEvents (Event.MOUSEMOVE); 
    return true; 
    } 
    <!-- DRAG DROP CODE --> 
    if(NS) { 
        window.captureEvents(Event.MOUSEUP|Event.MOUSEDOWN); 
        window.onmousedown = grabIt; 
        window.onmousemove = moveIt; 
        window.onmouseup = dropIt; 
    } 
    if(IE) { 
        document.onmousedown = grabIt; 
        document.onmousemove = moveIt; 
        document.onmouseup = dropIt; 
    } 
    if(NS || IE) action = window.setInterval("heartBeat()",1);