react-horizontal-scrolling-menu

滚动到横向列表中的特定项目

深度链接到某一行：聊天打开在正在进行的会话上，画廊打开在你分享的那张照片上。滚动容器位于库内部，但你不需要指向它 DOM 的 ref——onInit 把 api 交给你，由 scrollToItem 负责定位。
onInit scrolls straight to quito
Tokyo
Oslo
Lima
Cairo
Sydney
Quito
Seoul
Porto
Denver
Hanoi

轨道不会停在 Tokyo 挂载——onInit 会直接跳到 quito。拖到别处，再重新挂载，看它再次落在那里。

在 Storybook 中实时编辑此示例

工作原理

ScrollMenu 接受一个 onInit 回调，并在菜单渲染完毕、测量过项目之后调用它，传入与内部 VisibilityContext 所提供的同一个 api 对象。处理器用 getItemElementById(id) 查找元素，再交给 scrollToItem(item, ’auto’, ’start’)。因为 onInit 只在测量之后触发，对于已渲染的项目，查找不可能落空——无需 setTimeout，也无需重试循环。

行为与对齐

该 story 传入 ’auto’ 与 ’start’：’auto’ 不带动画地跳转，这正是初始位置所需要的——用户不会看到轨道停在第一个项目。’start’ 把项目的左边缘与轨道对齐。对于点击驱动的滚动，同一调用则使用 ’smooth’ 与 ’center’——就是下面的点击居中示例。

注意

完整源码

完整且可直接复制粘贴——这正是背后这份文件的 可在 Storybook 中实时编辑的版本.

ScrollToItem.source.tsx
import 'react-horizontal-scrolling-menu/dist/styles.css';

import styled from '@emotion/styled';
import React from 'react';
import {
  type publicApiType,
  ScrollMenu,
  VisibilityContext,
} from 'react-horizontal-scrolling-menu';

export function ScrollToItem() {
  const [items] = React.useState(() => getItems());
  const [selected, setSelected] = React.useState<string[]>([]);

  const isItemSelected = (id: string): boolean =>
    !!selected.find((el) => el === id);

  const handleItemClick = (itemId: string) => {
    const itemSelected = isItemSelected(itemId);

    setSelected((currentSelected: string[]) =>
      itemSelected
        ? currentSelected.filter((el) => el !== itemId)
        : currentSelected.concat(itemId),
    );
  };

  // `onInit` fires once the menu has rendered and measured its items,
  // so the api is safe to use right away — no timers needed.
  const scrollToItemOnInit = (api: publicApiType) => {
    const item = api.getItemElementById(getId(5));
    // const item = api.getItemElementByIndex('5') // or by index
    if (item) {
      api.scrollToItem(item, 'auto', 'start');
    }
  };

  return (
    <ScrollMenu
      LeftArrow={LeftArrow}
      RightArrow={RightArrow}
      onWheel={onWheel}
      onInit={scrollToItemOnInit}
    >
      {items.map(({ id }) => (
        <Card
          title={id}
          itemId={id} // NOTE: itemId is required for track items
          key={id}
          onClick={() => handleItemClick(id)}
          selected={isItemSelected(id)}
        />
      ))}
    </ScrollMenu>
  );
}

export default ScrollToItem;

function LeftArrow() {
  const visibility = React.useContext<publicApiType>(VisibilityContext);

  const disabled = visibility.useLeftArrowVisible();

  return (
    <Arrow
      disabled={disabled}
      onClick={() => visibility.scrollPrev()}
      testId="left-arrow"
    >
      Left
    </Arrow>
  );
}

function RightArrow() {
  const visibility = React.useContext<publicApiType>(VisibilityContext);

  const disabled = visibility.useRightArrowVisible();

  return (
    <Arrow
      disabled={disabled}
      onClick={() => visibility.scrollNext()}
      testId="right-arrow"
    >
      Right
    </Arrow>
  );
}

function Arrow({
  children,
  disabled,
  onClick,
  className,
  testId,
}: {
  children: React.ReactNode;
  disabled: boolean;
  onClick: VoidFunction;
  className?: string;
  testId: string;
}) {
  return (
    <ArrowButton
      disabled={disabled}
      onClick={onClick}
      className={'arrow' + `-${className}`}
      data-testid={testId}
    >
      {children}
    </ArrowButton>
  );
}
const ArrowButton = styled('button')((props) => ({
  cursor: 'pointer',
  display: 'flex',
  flexDirection: 'column',
  justifyContent: 'center',
  marginBottom: '2px',
  opacity: props.disabled ? '0' : '1',
  userSelect: 'none',
  borderRadius: '6px',
  borderWidth: '1px',
}));

function Card({
  onClick,
  selected,
  title,
  itemId,
}: {
  onClick: (context: publicApiType) => void;
  selected: boolean;
  title: string;
  itemId: string;
}) {
  const visibility = React.useContext<publicApiType>(VisibilityContext);
  const isVisible = visibility.useIsVisible(itemId, true);

  return (
    <CardBody
      data-cy={itemId}
      onClick={() => onClick(visibility)}
      onKeyDown={(ev: React.KeyboardEvent) => {
        ev.code === 'Enter' && onClick(visibility);
      }}
      data-testid="card"
      role="button"
      tabIndex={0}
      className="card"
      visible={isVisible}
      selected={selected}
    >
      <div className="header">
        <div>{title}</div>
        <div className="visible">visible: {JSON.stringify(isVisible)}</div>
        <div className="selected">selected: {JSON.stringify(!!selected)}</div>
      </div>
      <div className="background" />
    </CardBody>
  );
}
const CardBody = styled('div')<{ selected?: boolean; visible?: boolean }>(
  (props) => ({
    border: '1px solid',
    display: 'inline-block',
    margin: '0 10px',
    width: '160px',
    userSelect: 'none',
    borderRadius: '8px',
    overflow: 'hidden',

    '& .header': {
      backgroundColor: 'white',
    },

    '& .visible': {
      backgroundColor: props.visible ? 'transparent' : 'gray',
    },

    '& .background': {
      backgroundColor: props.selected ? 'green' : 'bisque',
      height: '200px',
    },
  }),
);

const getId = (index: number) => `${'test'}${index}`;

const getItems = () =>
  Array(10)
    .fill(0)
    .map((_, ind) => ({ id: getId(ind) }));

function onWheel(apiObj: publicApiType, ev: React.WheelEvent): void {
  // NOTE: no good standart way to distinguish touchpad scrolling gestures
  // but can assume that gesture will affect X axis, mouse scroll only Y axis
  // of if deltaY too small probably is it touchpad
  const isThouchpad = Math.abs(ev.deltaX) !== 0 || Math.abs(ev.deltaY) < 15;

  if (isThouchpad) {
    ev.stopPropagation();
    return;
  }

  if (ev.deltaY < 0) {
    apiObj.scrollNext();
  } else {
    apiObj.scrollPrev();
  }
}

相关示例

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