javascript YUI 读码日记之 YAHOO.util.Dom - Part.4

var getXY = function() {
    // 判断是否是 IE
    if (document.documentElement.getBoundingClientRect) {
        // 注1
        return function(el) {
            var box = el.getBoundingClientRect();

            var rootNode = el.ownerDocument;
            return [box.left + 
          Y.Dom.getDocumentScrollLeft(rootNode), box.top +
                    Y.Dom.getDocumentScrollTop(rootNode)];
        };
    } else {
        return function(el) {
            var pos = [el.offsetLeft, el.offsetTop];
            var parentNode = el.offsetParent;

            // 判断是否在 Safari 下,节点是否为 absolute ,
            // 并且父元素是否为 body
            // 注2.
            var accountForBody = (isSafari &&
                    Y.Dom.getStyle(el, 'position') == 'absolute' &&
                    el.offsetParent == el.ownerDocument.body);

            // 如果父元素不是自身
            if (parentNode != el) {
                while (parentNode) {
                    pos[0] += parentNode.offsetLeft;
                    pos[1] += parentNode.offsetTop;
                    if (!accountForBody && isSafari && 
                            Y.Dom.getStyle(parentNode,'position') 
                                                  == 'absolute' ) { 
                        accountForBody = true;
                    }
                    parentNode = parentNode.offsetParent;
                }
            }

            // 还是针对 Safari 的
            if (accountForBody) { //safari doubles in this case
                pos[0] -= el.ownerDocument.body.offsetLeft;
                pos[1] -= el.ownerDocument.body.offsetTop;
            } 
            parentNode = el.parentNode;

            // account for any scrolled ancestors
            while ( parentNode.tagName && 
                         !patterns.ROOT_TAG.test(parentNode.tagName) ) 
            {
               // work around opera inline/table scrollLeft/Top bug
               // 注3.
               if (Y.Dom.getStyle(parentNode, 'display')
                                  .search(/^inline|table-row.*$/i)) { 
                    pos[0] -= parentNode.scrollLeft;
                    pos[1] -= parentNode.scrollTop;
                }

                parentNode = parentNode.parentNode; 
            }

            return pos;
        };
    }
}() // NOTE: Executing for loadtime branching注. 有关 IE 的 getBoundingClientRect 方法,可以参考这里。
注. Safari 的 BUG,详细情况参见这里。
注. 参见老外的原话(出处):
"- Remove parent scroll UNLESS that parent is inline or a table 
to work around Opera inline/table scrollLeft/Top bug"
Fixed in Opera 9.5. (also, Opera 9.5 supports getBoundingClientRect 
and getClientRects.)最后,有关更多 DOM 的兼容性,可以参看 PPK 的总结(怎么又是他)。

%s 个评论

要回复文章请先登录注册