Overlay Scroll

Installation

Examples

Props

Files installed (2)

• app/components/ui/overlay-scroll/OverlayScroll.vue7.6 kB

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  <script setup lang="ts">
  import { onMounted, onScopeDispose, ref } from 'vue'
  import { cn } from '@/lib/utils'
  
  // Slack-style overlay scrollbar. Hides the native scrollbar entirely so the
  // scrolled content uses the full container width (no reservation), then draws
  // a thin auto-fading thumb absolutely positioned on top. Drag-to-scroll on the
  // thumb is supported via Pointer Events (mouse + touch + pen). Vertical only.
  //
  // Give the component a bounded height via the parent (e.g. `flex-1 min-h-0`
  // inside a flex column, or a fixed `h-*` / `max-h-*`). Without a bound it
  // expands to its content and the thumb is hidden.
  const props = withDefaults(
    defineProps<{
      // Thumb width in px when idle. Expands to ~2x on hover / drag.
      thumbWidth?: number
      // Right offset of the thumb from the inner edge, in px.
      thumbOffset?: number
      // ms of scroll inactivity before the thumb fades.
      idleHideMs?: number
      // Allow dragging the thumb to scroll.
      draggable?: boolean
      // Tailwind classes forwarded to the outer wrapper.
      class?: string
    }>(),
    {
      thumbWidth: 4,
      thumbOffset: 2,
      idleHideMs: 800,
      draggable: true,
    },
  )
  
  const scrollerEl = ref<HTMLElement | null>(null)
  const thumbEl = ref<HTMLElement | null>(null)
  const thumbHeight = ref(0)
  const thumbTop = ref(0)
  const showThumb = ref(false)
  const isHovered = ref(false)
  const isDragging = ref(false)
  let hideTimer: ReturnType<typeof setTimeout> | null = null
  
  const recompute = () => {
    const el = scrollerEl.value
    if (!el) return
    const ratio = el.clientHeight / el.scrollHeight
    if (!Number.isFinite(ratio) || ratio >= 1) {
      thumbHeight.value = 0
      return
    }
    thumbHeight.value = Math.max(24, el.clientHeight * ratio)
    const maxScroll = el.scrollHeight - el.clientHeight
    const maxThumb = el.clientHeight - thumbHeight.value
    thumbTop.value = maxScroll > 0 ? (el.scrollTop / maxScroll) * maxThumb : 0
  }
  
  const flashThumb = () => {
    if (thumbHeight.value === 0) return
    showThumb.value = true
    if (hideTimer) clearTimeout(hideTimer)
    hideTimer = setTimeout(() => {
      if (!isHovered.value && !isDragging.value) showThumb.value = false
    }, props.idleHideMs)
  }
  
  const onScroll = () => {
    recompute()
    flashThumb()
  }
  
  const onEnter = () => {
    isHovered.value = true
    recompute()
    if (thumbHeight.value > 0) showThumb.value = true
  }
  
  const onLeave = () => {
    isHovered.value = false
    if (isDragging.value) return
    if (hideTimer) clearTimeout(hideTimer)
    showThumb.value = false
  }
  
  // Pointer Events cover mouse + touch + pen on every modern browser
  // (Chrome 55+, Firefox 59+, Safari 13+, Edge). setPointerCapture keeps the
  // drag alive even if the pointer leaves the thumb, matching native feel.
  let activePointerId: number | null = null
  let dragStartY = 0
  let dragStartScrollTop = 0
  
  const onPointerMove = (e: PointerEvent) => {
    if (activePointerId !== e.pointerId) return
    const el = scrollerEl.value
    if (!el) return
    const maxScroll = el.scrollHeight - el.clientHeight
    const maxThumb = el.clientHeight - thumbHeight.value
    if (maxThumb <= 0) return
    const scrollRatio = maxScroll / maxThumb
    el.scrollTop = dragStartScrollTop + (e.clientY - dragStartY) * scrollRatio
  }
  
  const endDrag = (e?: PointerEvent) => {
    if (e && activePointerId !== e.pointerId) return
    isDragging.value = false
    if (thumbEl.value && activePointerId !== null) {
      try {
        thumbEl.value.releasePointerCapture(activePointerId)
      } catch {
        // pointer may already be released; ignore
      }
    }
    activePointerId = null
    thumbEl.value?.removeEventListener('pointermove', onPointerMove)
    thumbEl.value?.removeEventListener('pointerup', endDrag)
    thumbEl.value?.removeEventListener('pointercancel', endDrag)
    if (!isHovered.value) showThumb.value = false
  }
  
  const onThumbPointerDown = (e: PointerEvent) => {
    if (!props.draggable || !scrollerEl.value || !thumbEl.value) return
    if (e.pointerType === 'mouse' && e.button !== 0) return
    e.preventDefault()
    isDragging.value = true
    activePointerId = e.pointerId
    dragStartY = e.clientY
    dragStartScrollTop = scrollerEl.value.scrollTop
    thumbEl.value.setPointerCapture(e.pointerId)
    thumbEl.value.addEventListener('pointermove', onPointerMove)
    thumbEl.value.addEventListener('pointerup', endDrag)
    thumbEl.value.addEventListener('pointercancel', endDrag)
  }
  
  let resizeObserver: ResizeObserver | null = null
  let mutationObserver: MutationObserver | null = null
  
  onMounted(() => {
    recompute()
    if (!scrollerEl.value) return
  
    resizeObserver = new ResizeObserver(recompute)
    resizeObserver.observe(scrollerEl.value)
  
    const inner = scrollerEl.value.firstElementChild as HTMLElement | null
    if (inner) {
      resizeObserver.observe(inner)
      mutationObserver = new MutationObserver(recompute)
      mutationObserver.observe(inner, { childList: true, subtree: true })
    }
  })
  
  onScopeDispose(() => {
    resizeObserver?.disconnect()
    mutationObserver?.disconnect()
    if (hideTimer) clearTimeout(hideTimer)
    endDrag()
  })
  
  defineExpose({
    // Underlying scroller DOM element; call .scrollTo() on it from a parent.
    scrollerEl,
    // Force thumb recalc after a non-DOM size change.
    recompute,
  })
  </script>
  
  <template>
    <div
      data-uipkge
      data-slot="overlay-scroll"
      :class="cn('overlay-scroll relative', props.class)"
      @mouseenter="onEnter"
      @mouseleave="onLeave"
    >
      <div
        ref="scrollerEl"
        data-slot="overlay-scroll-viewport"
        class="overlay-scroll__inner h-full overflow-x-hidden overflow-y-auto"
        @scroll="onScroll"
      >
        <slot />
      </div>
      <div
        ref="thumbEl"
        data-slot="overlay-scroll-thumb"
        class="overlay-scroll__thumb"
        aria-hidden="true"
        :class="{
          'overlay-scroll__thumb--visible': showThumb,
          'overlay-scroll__thumb--dragging': isDragging,
          'overlay-scroll__thumb--draggable': draggable,
        }"
        :style="{
          width: `${thumbWidth}px`,
          /* Read the right offset from --ovs-thumb-right when an ancestor
             sets it (e.g. Sidebar pushes the thumb away from SidebarRail),
             otherwise fall back to the prop. Lets the same primitive sit
             flush in a card AND clear a rail without per-call config. */
          right: `var(--ovs-thumb-right, ${thumbOffset}px)`,
          height: `${thumbHeight}px`,
          transform: `translateY(${thumbTop}px)`,
        }"
        @pointerdown="onThumbPointerDown"
      />
    </div>
  </template>
  
  <style scoped>
  .overlay-scroll__inner {
    scrollbar-width: none;
    -ms-overflow-style: none;
    /* Stop wheel events from chaining to the page once the inner scroller
       hits its top/bottom. Without this, scrolling a long activity feed
       past its last item keeps scrolling the surrounding page — confusing
       when the inner region is a clearly bounded card. */
    overscroll-behavior: contain;
  }
  .overlay-scroll__inner::-webkit-scrollbar {
    display: none;
    width: 0;
    height: 0;
  }
  .overlay-scroll__thumb {
    position: absolute;
    top: 0;
    border-radius: 2px;
    background: var(--muted-foreground);
    opacity: 0;
    pointer-events: none;
    touch-action: none;
    user-select: none;
    -webkit-user-select: none;
    transition:
      opacity 0.2s ease,
      background-color 0.15s,
      width 0.12s ease;
    will-change: transform, opacity;
  }
  .overlay-scroll__thumb--draggable {
    cursor: pointer;
  }
  .overlay-scroll__thumb--visible {
    opacity: 0.4;
    pointer-events: auto;
  }
  .overlay-scroll:hover .overlay-scroll__thumb--visible {
    opacity: 0.6;
  }
  .overlay-scroll:hover .overlay-scroll__thumb--draggable:hover {
    opacity: 0.8;
    width: 8px !important;
    background: var(--foreground);
  }
  .overlay-scroll__thumb--dragging {
    opacity: 1 !important;
    background: var(--foreground) !important;
    width: 8px !important;
  }
  </style>
  

• app/components/ui/overlay-scroll/index.ts0.1 kB

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Raw manifest:https://uipkge.dev/r/vue/overlay-scroll.json

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