114 lines
3.1 KiB
Vue
114 lines
3.1 KiB
Vue
import { Data } from '../../_util/type';
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import { Ref } from 'vue';
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import raf from '../../_util/raf';
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import { GetKey } from '../interface';
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import { ListState } from '../List';
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export default function useScrollTo(
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containerRef: Ref<Element | undefined>,
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state: ListState,
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heights: Data,
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props,
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getKey: GetKey,
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collectHeight: () => void,
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syncScrollTop: (newTop: number) => void,
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triggerFlash: () => void,
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) {
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let scroll: number | null = null;
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return (arg?: any) => {
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// When not argument provided, we think dev may want to show the scrollbar
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if (arg === null || arg === undefined) {
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triggerFlash();
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return;
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}
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// Normal scroll logic
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raf.cancel(scroll!);
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const data = state.mergedData;
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const itemHeight = props.itemHeight;
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if (typeof arg === 'number') {
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syncScrollTop(arg);
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} else if (arg && typeof arg === 'object') {
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let index: number;
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const { align } = arg;
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if ('index' in arg) {
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({ index } = arg);
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} else {
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index = data.findIndex((item: object) => getKey(item) === arg.key);
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}
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const { offset = 0 } = arg;
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// We will retry 3 times in case dynamic height shaking
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const syncScroll = (times: number, targetAlign?: 'top' | 'bottom') => {
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if (times < 0 || !containerRef.value) return;
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const height = containerRef.value.clientHeight;
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let needCollectHeight = false;
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let newTargetAlign = targetAlign;
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// Go to next frame if height not exist
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if (height) {
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const mergedAlign = targetAlign || align;
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// Get top & bottom
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let stackTop = 0;
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let itemTop = 0;
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let itemBottom = 0;
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for (let i = 0; i <= index; i += 1) {
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const key = getKey(data[i]);
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itemTop = stackTop;
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const cacheHeight = heights[key!];
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itemBottom = itemTop + (cacheHeight === undefined ? itemHeight : cacheHeight);
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stackTop = itemBottom;
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if (i === index && cacheHeight === undefined) {
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needCollectHeight = true;
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}
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}
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// Scroll to
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let targetTop: number | null = null;
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switch (mergedAlign) {
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case 'top':
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targetTop = itemTop - offset;
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break;
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case 'bottom':
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targetTop = itemBottom - height + offset;
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break;
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default: {
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const { scrollTop } = containerRef.value;
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const scrollBottom = scrollTop + height;
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if (itemTop < scrollTop) {
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newTargetAlign = 'top';
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} else if (itemBottom > scrollBottom) {
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newTargetAlign = 'bottom';
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}
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}
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}
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if (targetTop !== null && targetTop !== containerRef.value.scrollTop) {
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syncScrollTop(targetTop);
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}
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}
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// We will retry since element may not sync height as it described
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scroll = raf(() => {
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if (needCollectHeight) {
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collectHeight();
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}
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syncScroll(times - 1, newTargetAlign);
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});
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};
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syncScroll(3);
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}
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};
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}
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