Sigma ScrollKit

Advanced virtual scrolling module for Vue 3.

Originally created for the parent project: Sigma File Manager v2.

Features

• Supports complex list view.
• Supports complex grid view.
• Programmatic control.
• Grid view generates automatically based on the specified min column width, and adapts to the viewport / window size.
• Supports arbitrary dynamic item height, row and column gaps.
• Allows to build complex virtual scrollers programmatically with spacers, dividers and item groups of different sizes.
• Supports custom scrollbars.
• Emits many useful events, including scroll statuses like is-scrolling, bottom-reached, etc.
• Scrollbar doesn't jitter when scrolling because the item height is known in advance.

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Installation

npm install sigma-scrollkit

Usage

The module renders a list of virtual rows (virtual entries) in both the list and grid views. The difference is that in list view the column count is always 1.

Demo playground

Interface

interface VirtualEntryItem {
  [key: string]: unknown;
}

export interface VirtualEntry {
  id: number | string;
  height: number;
  rowGap: number;
  columnGap: number;
  items: VirtualEntryItem[];
  [key: string]: unknown;
}

interface Props {
  virtualEntries: VirtualEntry[];
  scrollerId: string;
  layoutType: "list" | "grid";
  minColumnWidth?: number;
  bufferItemCount?: number;
  calcExtraInfo?: boolean;
  topOffsetTrigger?: number;
  bottomOffsetTrigger?: number;
}

Template structure

<script setup>
import {VirtualScroller, VirtualScrollerRow} from 'sigma-scrollkit'
import type {VirtualEntry} from 'sigma-scrollkit/types/shared';

// ...
</script>

<template>
  <VirtualScroller
    ref="virtualGridRef"
    layout-type="grid"
    :scroller-id="0"
    :virtual-entries="formattedDirEntries"
    :min-column-width="minColumnWidth"
    @viewport-mounted="onViewportMounted"
    @top-reached="onTopReached"
    @bottom-reached="onBottomReached"
    @is-scrollable="onIsScrollable"
  >
    <template #viewport="{ renderedItems, scrolling, maxColumns }">
      <VirtualScrollerRow
        v-for="virtualEntry in renderedItems"
        :key="virtualEntry.id"
        :virtual-entry="virtualEntry"
        :max-columns="maxColumns"
      >
        <Component
          :is="componentReference[virtualEntry.component]"
          v-for="(item, index) in virtualEntry.items"
          :key="index"
          :height="virtualEntry.height"
          :hover-enabled="!scrolling"
          :dir-entry="item"
          layout-type="grid"
          v-bind="'props' in item && item.props"
          :style="`height: ${virtualEntry.height}px`"
        />
      </VirtualScrollerRow>
    </template>
  </VirtualScroller>
</template>

Components

The module exports 2 components:

• VirtualScroller - main container component, calculates all the logic and renders virtual list / grid.
• VirtualScrollerRow - component needed to wrap each row in the virtual container.

API

VirtualScroller props:

virtualEntries

• Required: true
• Type: VirtualEntry[]

scrollerId

• Required: true
• Type: string

layoutType

• Required: true
• Type: 'list' | 'grid'

minColumnWidth

• Required: false
• Type: number

bufferItemCount

• Required: false
• Type: number

calcExtraInfo

• Required: false
• Type: boolean
• Description: if true, extra data properties will be calculated and emited in the scroll event:
  • scrollSpeed: current scroll speed

VirtualScroller events:

viewport-mounted

• Type: {viewport: Ref<HTMLElement | null>; selector: string}

scroll

• Type: ScrollEmitValue

scrolling

• Type: boolean

is-scrollable

• Type: boolean

top-reached

• Type: boolean

bottom-reached

• Type: boolean

VirtualScrollerRow props:

virtualEntry

• Required: true
• Type: VirtualEntry

maxColumns

• Required: true
• Type: number