@sms-frontend/components
Version:
SMS Design React UI Library.
126 lines (125 loc) • 4.91 kB
JavaScript
var __rest = (this && this.__rest) || function (s, e) {
var t = {};
for (var p in s) if (Object.prototype.hasOwnProperty.call(s, p) && e.indexOf(p) < 0)
t[p] = s[p];
if (s != null && typeof Object.getOwnPropertySymbols === "function")
for (var i = 0, p = Object.getOwnPropertySymbols(s); i < p.length; i++) {
if (e.indexOf(p[i]) < 0 && Object.prototype.propertyIsEnumerable.call(s, p[i]))
t[p[i]] = s[p[i]];
}
return t;
};
import { findDOMNode } from 'react-dom';
import getStringLength from '../../../_util/getStringLength';
/**
* 为了计算方便，定位元素的下标可能返回数组长度，代表最后一个元素
*/
export var GHOST_ITEM_KEY = '__rc_ghost_item__';
/**
* 根据滚动条当前的滚动百分比，计算出基准元素
* 在基准元素的上方和下方渲染可见区域的其他元素
*/
export function getLocationItem(scrollPtg, total) {
var itemIndex = Math.floor(scrollPtg * total);
var itemTopPtg = itemIndex / total;
var offsetPtg = (scrollPtg - itemTopPtg) / (1 / total);
return {
index: itemIndex,
// scrollPtg >= itemTopPtg，计算结果为元素应当补充的滚动距离相对自身高度的偏移量
offsetPtg: Number.isNaN(offsetPtg) ? 0 : offsetPtg,
};
}
/**
* 获取HTML元素高度
*/
export function getNodeHeight(node) {
var element = findDOMNode(node);
return element ? element.offsetHeight : 0;
}
/**
* 获取有效的scrollTop值
* Safari的缓动效果会获得负值的scrollTop
*/
export function getValidScrollTop(scrollTop, scrollRange) {
return scrollTop < 0 ? 0 : scrollTop > scrollRange ? scrollRange : scrollTop;
}
/**
* 视口已滚动距离 / 总可滚动距离
*/
export function getScrollPercentage(_a) {
var scrollTop = _a.scrollTop, scrollHeight = _a.scrollHeight, clientHeight = _a.clientHeight;
var scrollRange = scrollHeight - clientHeight;
return scrollRange <= 0 ? 0 : getValidScrollTop(scrollTop, scrollRange) / scrollRange;
}
/**
* 计算需要渲染的元素的开始下标、结束下标和用于定位的元素下标
*/
export function getRangeIndex(scrollPtg, itemCount, visibleCount) {
var _a = getLocationItem(scrollPtg, itemCount), index = _a.index, offsetPtg = _a.offsetPtg;
var beforeCount = Math.ceil(scrollPtg * visibleCount);
var afterCount = Math.ceil((1 - scrollPtg) * visibleCount);
return {
itemIndex: index,
itemOffsetPtg: offsetPtg,
startIndex: Math.max(0, index - beforeCount),
endIndex: Math.min(itemCount - 1, index + afterCount),
};
}
/**
* 计算元素相对于视口顶部的偏移量
*/
export function getItemRelativeTop(_a) {
var itemHeight = _a.itemHeight, itemOffsetPtg = _a.itemOffsetPtg, scrollPtg = _a.scrollPtg, clientHeight = _a.clientHeight;
return Math.floor(clientHeight * scrollPtg - itemHeight * itemOffsetPtg);
}
/**
* 计算元素相对于整个滚动区域顶部的偏移量
*/
export function getItemAbsoluteTop(_a) {
var scrollTop = _a.scrollTop, rest = __rest(_a, ["scrollTop"]);
return scrollTop + getItemRelativeTop(rest);
}
/**
* 计算某一指定下标的元素相对于视口顶部的偏移量
*/
export function getCompareItemRelativeTop(_a) {
var locatedItemRelativeTop = _a.locatedItemRelativeTop, locatedItemIndex = _a.locatedItemIndex, compareItemIndex = _a.compareItemIndex, startIndex = _a.startIndex, endIndex = _a.endIndex, getItemKey = _a.getItemKey, itemElementHeights = _a.itemElementHeights, itemHeight = _a.itemHeight;
var compareItemTop = locatedItemRelativeTop;
var compareItemKey = getItemKey(compareItemIndex);
if (compareItemIndex <= locatedItemIndex) {
for (var index = locatedItemIndex; index >= startIndex; index -= 1) {
var key = getItemKey(index);
if (key === compareItemKey) {
break;
}
var prevItemKey = getItemKey(index - 1);
compareItemTop -= itemElementHeights[prevItemKey] || itemHeight;
}
}
else {
for (var index = locatedItemIndex; index <= endIndex; index += 1) {
var key = getItemKey(index);
if (key === compareItemKey) {
break;
}
compareItemTop += itemElementHeights[key] || itemHeight;
}
}
return compareItemTop;
}
export function getLongestItemIndex(data) {
var result = -1;
var length = 0;
data.forEach(function (item, index) {
var _a;
item = typeof item === 'string' ? item : (_a = item.props) === null || _a === void 0 ? void 0 : _a.children;
if (typeof item === 'string') {
var _length = getStringLength(item);
if (_length > length) {
length = _length;
result = index;
}
}
});
return result;
}