ant-design-vue/components/vc-table/stickyScrollBar.tsx

import type { Ref } from 'vue';
import { computed, defineComponent, onBeforeUnmount, onMounted, ref, watch } from 'vue';
import addEventListenerWrap from '../vc-util/Dom/addEventListener';
import { getOffset } from '../vc-util/Dom/css';
import classNames from '../_util/classNames';
import type { MouseEventHandler } from '../_util/EventInterface';
import getScrollBarSize from '../_util/getScrollBarSize';
import { useInjectTable } from './context/TableContext';
import { useLayoutState } from './hooks/useFrame';

interface StickyScrollBarProps {
  scrollBodyRef: Ref<HTMLElement>;
  onScroll: (params: { scrollLeft?: number }) => void;
  offsetScroll: number;
  container: HTMLElement | Window;
}

export default defineComponent<StickyScrollBarProps>({
  name: 'StickyScrollBar',
  inheritAttrs: false,
  props: ['offsetScroll', 'container', 'scrollBodyRef'] as any,
  emits: ['scroll'],
  setup(props, { emit, expose }) {
    const tableContext = useInjectTable();
    const bodyScrollWidth = computed(() => props.scrollBodyRef.value.scrollWidth || 0);
    const bodyWidth = computed(() => props.scrollBodyRef.value.clientWidth || 0);
    const scrollBarWidth = computed(
      () => bodyScrollWidth.value && bodyWidth.value * (bodyWidth.value / bodyScrollWidth.value),
    );

    const scrollBarRef = ref();

    const [scrollState, setScrollState] = useLayoutState({
      scrollLeft: 0,
      isHiddenScrollBar: false,
    });

    const refState = ref({
      delta: 0,
      x: 0,
    });

    const isActive = ref(false);

    const onMouseUp: MouseEventHandler = () => {
      isActive.value = false;
    };

    const onMouseDown: MouseEventHandler = event => {
      refState.value = { delta: event.pageX - scrollState.value.scrollLeft, x: 0 };
      isActive.value = true;
      event.preventDefault();
    };

    const onMouseMove: MouseEventHandler = event => {
      // https://developer.mozilla.org/en-US/docs/Web/API/MouseEvent/buttons
      const { buttons } = event || (window?.event as any);
      if (!isActive.value || buttons === 0) {
        // If out body mouse up, we can set isActive false when mouse move
        if (isActive.value) {
          isActive.value = false;
        }
        return;
      }
      let left: number = refState.value.x + event.pageX - refState.value.x - refState.value.delta;

      if (left <= 0) {
        left = 0;
      }

      if (left + scrollBarWidth.value >= bodyWidth.value) {
        left = bodyWidth.value - scrollBarWidth.value;
      }
      emit('scroll', {
        scrollLeft: (left / bodyWidth.value) * (bodyScrollWidth.value + 2),
      });

      refState.value.x = event.pageX;
    };

    const onContainerScroll = () => {
      const tableOffsetTop = getOffset(props.scrollBodyRef.value).top;
      const tableBottomOffset = tableOffsetTop + props.scrollBodyRef.value.offsetHeight;
      const currentClientOffset =
        props.container === window
          ? document.documentElement.scrollTop + window.innerHeight
          : getOffset(props.container).top + (props.container as HTMLElement).clientHeight;

      if (
        tableBottomOffset - getScrollBarSize() <= currentClientOffset ||
        tableOffsetTop >= currentClientOffset - props.offsetScroll
      ) {
        setScrollState(state => ({
          ...state,
          isHiddenScrollBar: true,
        }));
      } else {
        setScrollState(state => ({
          ...state,
          isHiddenScrollBar: false,
        }));
      }
    };

    const setScrollLeft = (left: number) => {
      setScrollState(state => {
        return {
          ...state,
          scrollLeft: (left / bodyScrollWidth.value) * bodyWidth.value || 0,
        };
      });
    };

    expose({
      setScrollLeft,
    });
    let onMouseUpListener = null;
    let onMouseMoveListener = null;
    let onResizeListener = null;
    let onScrollListener = null;
    onMounted(() => {
      onMouseUpListener = addEventListenerWrap(document.body, 'mouseup', onMouseUp, false);
      onMouseMoveListener = addEventListenerWrap(document.body, 'mousemove', onMouseMove, false);
      onResizeListener = addEventListenerWrap(window, 'resize', onContainerScroll, false);
    });

    watch(
      [scrollBarWidth, isActive],
      () => {
        onContainerScroll();
      },
      { immediate: true },
    );

    watch(
      () => props.container,
      () => {
        onScrollListener?.remove();
        onScrollListener = addEventListenerWrap(
          props.container,
          'scroll',
          onContainerScroll,
          false,
        );
      },
      { immediate: true, flush: 'post' },
    );

    onBeforeUnmount(() => {
      onMouseUpListener?.remove();
      onMouseMoveListener?.remove();
      onScrollListener?.remove();
      onResizeListener?.remove();
    });

    watch(
      () => ({ ...scrollState.value }),
      (newState, preState) => {
        if (
          newState.isHiddenScrollBar !== preState?.isHiddenScrollBar &&
          !newState.isHiddenScrollBar
        ) {
          setScrollState(state => {
            const bodyNode = props.scrollBodyRef.value;
            if (!bodyNode) {
              return state;
            }
            return {
              ...state,
              scrollLeft: (bodyNode.scrollLeft / bodyNode.scrollWidth) * bodyNode.clientWidth,
            };
          });
        }
      },
      { immediate: true },
    );
    const scrollbarSize = getScrollBarSize();

    return () => {
      if (
        bodyScrollWidth.value <= bodyWidth.value ||
        !scrollBarWidth.value ||
        scrollState.value.isHiddenScrollBar
      ) {
        return null;
      }
      const { prefixCls } = tableContext;
      return (
        <div
          style={{
            height: `${scrollbarSize}px`,
            width: `${bodyWidth.value}px`,
            bottom: `${props.offsetScroll}px`,
          }}
          class={`${prefixCls}-sticky-scroll`}
        >
          <div
            onMousedown={onMouseDown}
            ref={scrollBarRef}
            class={classNames(`${prefixCls}-sticky-scroll-bar`, {
              [`${prefixCls}-sticky-scroll-bar-active`]: isActive,
            })}
            style={{
              width: `${scrollBarWidth.value}px`,
              transform: `translate3d(${scrollState.value.scrollLeft}px, 0, 0)`,
            }}
          />
        </div>
      );
    };
  },
});