Dynamic Content and Measurement

/**
 * Measures dynamic cell content for accurate virtualization
 * @param props - CellMeasurer configuration
 */
function CellMeasurer(props: {
  /** Cache instance for storing measurements */
  cache: CellMeasurerCache;
  /** Function that renders the measurable content */
  children: (params: {measure: () => void, registerChild: (element: HTMLElement) => void}) => React.Node;
  /** Column index (for Grid components) */
  columnIndex?: number;
  /** Parent component reference */
  parent: React.Component;
  /** Row index */
  rowIndex: number;
}): React.Component;

/**
 * Cache for CellMeasurer measurements
 */
class CellMeasurerCache {
  /**
   * Creates a new measurement cache
   * @param params - Cache configuration
   */
  constructor(params: {
    /** Default height for unmeasured cells */
    defaultHeight?: number;
    /** Default width for unmeasured cells */
    defaultWidth?: number;
    /** Whether all cells have fixed height */
    fixedHeight?: boolean;
    /** Whether all cells have fixed width */
    fixedWidth?: boolean;
    /** Minimum height for any cell */
    minHeight?: number;
    /** Minimum width for any cell */
    minWidth?: number;
    /** Function to generate cache keys */
    keyMapper?: (rowIndex: number, columnIndex: number) => string;
  });

  /** Clear cached measurements for a specific cell */
  clear(rowIndex: number, columnIndex?: number): void;

  /** Clear all cached measurements */
  clearAll(): void;

  /** Get cached height for a cell */
  getHeight(rowIndex: number, columnIndex?: number): number;

  /** Get cached width for a cell */
  getWidth(rowIndex: number, columnIndex?: number): number;

  /** Check if a cell has been measured */
  has(rowIndex: number, columnIndex?: number): boolean;

  /** Check if cache uses fixed height */
  hasFixedHeight(): boolean;

  /** Check if cache uses fixed width */
  hasFixedWidth(): boolean;

  /** Row height function for List/Grid components */
  rowHeight(params: {index: number}): number;

  /** Column width function for Grid components */
  columnWidth(params: {index: number}): number;

  /** Set cached dimensions for a cell */
  set(rowIndex: number, columnIndex: number, width: number, height: number): void;

  /** Default height value */
  get defaultHeight(): number;

  /** Default width value */
  get defaultWidth(): number;
}

import React from 'react';
import { CellMeasurer, CellMeasurerCache, List } from 'react-virtualized';

// Dynamic height list with CellMeasurer
function DynamicHeightList({ items }) {
  const cache = new CellMeasurerCache({
    fixedWidth: true,
    defaultHeight: 100
  });

  const rowRenderer = ({ index, key, parent, style }) => (
    <CellMeasurer
      cache={cache}
      columnIndex={0}
      key={key}
      parent={parent}
      rowIndex={index}
    >
      <div style={style} className="dynamic-row">
        <h3>{items[index].title}</h3>
        <p>{items[index].description}</p>
        <div className="tags">
          {items[index].tags.map(tag => (
            <span key={tag} className="tag">{tag}</span>
          ))}
        </div>
      </div>
    </CellMeasurer>
  );

  return (
    <List
      deferredMeasurementCache={cache}
      height={600}
      rowCount={items.length}
      rowHeight={cache.rowHeight}
      rowRenderer={rowRenderer}
      width={400}
    />
  );
}

// Dynamic grid with variable cell sizes
function DynamicGrid({ data }) {
  const cache = new CellMeasurerCache({
    defaultHeight: 80,
    defaultWidth: 120,
    fixedHeight: false,
    fixedWidth: false
  });

  const cellRenderer = ({ columnIndex, key, parent, rowIndex, style }) => (
    <CellMeasurer
      cache={cache}
      columnIndex={columnIndex}
      key={key}
      parent={parent}
      rowIndex={rowIndex}
    >
      <div style={style} className="dynamic-cell">
        <div className="cell-content">
          {data[rowIndex][columnIndex]}
        </div>
      </div>
    </CellMeasurer>
  );

  return (
    <Grid
      cellRenderer={cellRenderer}
      columnCount={data[0].length}
      columnWidth={cache.columnWidth}
      deferredMeasurementCache={cache}
      height={500}
      rowCount={data.length}
      rowHeight={cache.rowHeight}
      width={800}
    />
  );
}

// List with image content requiring measurement
function ImageList({ posts }) {
  const cache = new CellMeasurerCache({
    fixedWidth: true,
    minHeight: 200
  });

  const rowRenderer = ({ index, key, parent, style }) => {
    const post = posts[index];
    
    return (
      <CellMeasurer
        cache={cache}
        columnIndex={0}
        key={key}
        parent={parent}
        rowIndex={index}
      >
        {({ measure, registerChild }) => (
          <div ref={registerChild} style={style} className="post-item">
            <img
              src={post.imageUrl}
              alt={post.title}
              onLoad={measure}
              style={{ width: '100%', height: 'auto' }}
            />
            <div className="post-content">
              <h3>{post.title}</h3>
              <p>{post.excerpt}</p>
            </div>
          </div>
        )}
      </CellMeasurer>
    );
  };

  return (
    <List
      deferredMeasurementCache={cache}
      height={600}
      rowCount={posts.length}
      rowHeight={cache.rowHeight}
      rowRenderer={rowRenderer}
      width={400}
    />
  );
}

/**
 * Manages loading additional data as user scrolls
 * @param props - InfiniteLoader configuration
 */
function InfiniteLoader(props: {
  /** Function that renders the scrollable component */
  children: (params: {
    onRowsRendered: (params: {overscanStartIndex: number, overscanStopIndex: number, startIndex: number, stopIndex: number}) => void,
    registerChild: (element: React.Component) => void
  }) => React.Node;
  /** Function to check if a row is loaded */
  isRowLoaded: (params: {index: number}) => boolean;
  /** Function to load more rows */
  loadMoreRows: (params: {startIndex: number, stopIndex: number}) => Promise<any>;
  /** Total number of rows (including unloaded) */
  rowCount: number;
  /** Minimum number of rows to batch load (default: 10) */
  minimumBatchSize?: number;
  /** Number of rows to look ahead for loading (default: 15) */
  threshold?: number;
}): React.Component;

import React, { useState, useCallback } from 'react';
import { InfiniteLoader, List, AutoSizer } from 'react-virtualized';

// Basic infinite loading list
function InfiniteList() {
  const [items, setItems] = useState([]);
  const [loading, setLoading] = useState(false);

  const isRowLoaded = ({ index }) => {
    return !!items[index];
  };

  const loadMoreRows = useCallback(async ({ startIndex, stopIndex }) => {
    if (loading) return;
    
    setLoading(true);
    try {
      // Simulate API call
      const newItems = await fetchItems(startIndex, stopIndex);
      setItems(prevItems => {
        const updatedItems = [...prevItems];
        newItems.forEach((item, index) => {
          updatedItems[startIndex + index] = item;
        });
        return updatedItems;
      });
    } finally {
      setLoading(false);
    }
  }, [loading]);

  const rowRenderer = ({ index, key, style }) => {
    const item = items[index];
    
    if (!item) {
      return (
        <div key={key} style={style} className="loading-row">
          Loading...
        </div>
      );
    }

    return (
      <div key={key} style={style} className="item-row">
        <h4>{item.title}</h4>
        <p>{item.description}</p>
      </div>
    );
  };

  return (
    <div style={{ height: 400, width: '100%' }}>
      <InfiniteLoader
        isRowLoaded={isRowLoaded}
        loadMoreRows={loadMoreRows}
        rowCount={10000} // Total possible rows
        threshold={15}
      >
        {({ onRowsRendered, registerChild }) => (
          <AutoSizer>
            {({ height, width }) => (
              <List
                ref={registerChild}
                height={height}
                width={width}
                rowCount={10000}
                rowHeight={80}
                rowRenderer={rowRenderer}
                onRowsRendered={onRowsRendered}
              />
            )}
          </AutoSizer>
        )}
      </InfiniteLoader>
    </div>
  );
}

// Advanced infinite loader with error handling
function AdvancedInfiniteList({ apiEndpoint }) {
  const [items, setItems] = useState([]);
  const [errors, setErrors] = useState({});
  const [hasNextPage, setHasNextPage] = useState(true);

  const isRowLoaded = ({ index }) => {
    return !!items[index] || !!errors[index];
  };

  const loadMoreRows = async ({ startIndex, stopIndex }) => {
    // Don't load if we've reached the end
    if (!hasNextPage && startIndex >= items.length) {
      return;
    }

    try {
      const response = await fetch(
        `${apiEndpoint}?start=${startIndex}&count=${stopIndex - startIndex + 1}`
      );
      
      if (!response.ok) {
        throw new Error(`HTTP ${response.status}`);
      }

      const data = await response.json();
      
      setItems(prevItems => {
        const updatedItems = [...prevItems];
        data.items.forEach((item, index) => {
          updatedItems[startIndex + index] = item;
        });
        return updatedItems;
      });

      setHasNextPage(data.hasMore);
      
      // Clear any previous errors for this range
      setErrors(prevErrors => {
        const updatedErrors = { ...prevErrors };
        for (let i = startIndex; i <= stopIndex; i++) {
          delete updatedErrors[i];
        }
        return updatedErrors;
      });

    } catch (error) {
      // Mark these indices as having errors
      setErrors(prevErrors => {
        const updatedErrors = { ...prevErrors };
        for (let i = startIndex; i <= stopIndex; i++) {
          updatedErrors[i] = error.message;
        }
        return updatedErrors;
      });
    }
  };

  const rowRenderer = ({ index, key, style }) => {
    const item = items[index];
    const error = errors[index];

    if (error) {
      return (
        <div key={key} style={style} className="error-row">
          Error loading item: {error}
          <button onClick={() => loadMoreRows({ startIndex: index, stopIndex: index })}>
            Retry
          </button>
        </div>
      );
    }

    if (!item) {
      return (
        <div key={key} style={style} className="loading-row">
          <div className="spinner" />
          Loading...
        </div>
      );
    }

    return (
      <div key={key} style={style} className="item-row">
        <img src={item.thumbnail} alt="" />
        <div className="item-content">
          <h4>{item.title}</h4>
          <p>{item.description}</p>
          <small>ID: {item.id}</small>
        </div>
      </div>
    );
  };

  const estimatedRowCount = hasNextPage ? items.length + 100 : items.length;

  return (
    <div style={{ height: 500, width: '100%' }}>
      <InfiniteLoader
        isRowLoaded={isRowLoaded}
        loadMoreRows={loadMoreRows}
        rowCount={estimatedRowCount}
        minimumBatchSize={20}
        threshold={10}
      >
        {({ onRowsRendered, registerChild }) => (
          <AutoSizer>
            {({ height, width }) => (
              <List
                ref={registerChild}
                height={height}
                width={width}
                rowCount={estimatedRowCount}
                rowHeight={100}
                rowRenderer={rowRenderer}
                onRowsRendered={onRowsRendered}
              />
            )}
          </AutoSizer>
        )}
      </InfiniteLoader>
    </div>
  );
}

// Helper function to simulate API calls
async function fetchItems(startIndex, stopIndex) {
  // Simulate network delay
  await new Promise(resolve => setTimeout(resolve, 500));
  
  const count = stopIndex - startIndex + 1;
  return Array.from({ length: count }, (_, i) => ({
    id: startIndex + i,
    title: `Item ${startIndex + i}`,
    description: `Description for item ${startIndex + i}`,
    thumbnail: `https://picsum.photos/60/60?random=${startIndex + i}`
  }));
}