4cd4fd28
 郭伟龙
feat: 初始化项目
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// @flow
import getWindow from './getWindow';
import getNodeName from './getNodeName';
import getComputedStyle from './getComputedStyle';
import { isHTMLElement, isShadowRoot } from './instanceOf';
import isTableElement from './isTableElement';
import getParentNode from './getParentNode';
import getUAString from '../utils/userAgent';
function getTrueOffsetParent(element: Element): ?Element {
if (
!isHTMLElement(element) ||
// https://github.com/popperjs/popper-core/issues/837
getComputedStyle(element).position === 'fixed'
) {
return null;
}
return element.offsetParent;
}
// `.offsetParent` reports `null` for fixed elements, while absolute elements
// return the containing block
function getContainingBlock(element: Element) {
const isFirefox = /firefox/i.test(getUAString());
const isIE = /Trident/i.test(getUAString());
if (isIE && isHTMLElement(element)) {
// In IE 9, 10 and 11 fixed elements containing block is always established by the viewport
const elementCss = getComputedStyle(element);
if (elementCss.position === 'fixed') {
return null;
}
}
let currentNode = getParentNode(element);
if (isShadowRoot(currentNode)) {
currentNode = currentNode.host;
}
while (
isHTMLElement(currentNode) &&
['html', 'body'].indexOf(getNodeName(currentNode)) < 0
) {
const css = getComputedStyle(currentNode);
// This is non-exhaustive but covers the most common CSS properties that
// create a containing block.
// https://developer.mozilla.org/en-US/docs/Web/CSS/Containing_block#identifying_the_containing_block
if (
css.transform !== 'none' ||
css.perspective !== 'none' ||
css.contain === 'paint' ||
['transform', 'perspective'].indexOf(css.willChange) !== -1 ||
(isFirefox && css.willChange === 'filter') ||
(isFirefox && css.filter && css.filter !== 'none')
) {
return currentNode;
} else {
currentNode = currentNode.parentNode;
}
}
return null;
}
// Gets the closest ancestor positioned element. Handles some edge cases,
// such as table ancestors and cross browser bugs.
export default function getOffsetParent(element: Element) {
const window = getWindow(element);
let offsetParent = getTrueOffsetParent(element);
while (
offsetParent &&
isTableElement(offsetParent) &&
getComputedStyle(offsetParent).position === 'static'
) {
offsetParent = getTrueOffsetParent(offsetParent);
}
if (
offsetParent &&
(getNodeName(offsetParent) === 'html' ||
(getNodeName(offsetParent) === 'body' &&
getComputedStyle(offsetParent).position === 'static'))
) {
return window;
}
return offsetParent || getContainingBlock(element) || window;
}
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