File Preview Kit

File Preview Kit is a lightweight Flutter library for parsing and previewing XLSX, CSV, and DOCX files through a unified set of preview widgets.

It prioritizes readable content and does not guarantee pixel-perfect reproduction of Microsoft Excel or Word layouts.

Instructions for AI Coding Agents

Treat this section as the usage contract for generated code.

Supported contract

• Supported formats: XLSX, UTF-8 CSV, and DOCX.
• File content must be provided as Uint8List.
• Always provide either fileName with a supported extension or mimeType so the format can be detected. If both are provided, fileName takes precedence.
• Prefer the unified FilePreviewView with PreviewSource.bytes(...).
• Do not invent APIs for file paths, URLs, PDF files, legacy .xls/.doc files, password-protected files, or pixel-perfect Microsoft Office rendering.

Installation

dependencies:
  file_preview_kit: ^0.0.5

Preferred usage

import 'dart:typed_data';

import 'package:file_preview_kit/file_preview_kit.dart';
import 'package:flutter/material.dart';

class FilePreviewPage extends StatelessWidget {
  final Uint8List bytes;
  final String fileName;

  const FilePreviewPage({
    super.key,
    required this.bytes,
    required this.fileName,
  });

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: Text(fileName)),
      body: FilePreviewView(
        source: PreviewSource.bytes(bytes, fileName: fileName),
        onLinkTap: (target) => debugPrint('Open link: $target'),
      ),
    );
  }
}

onLinkTap receives links found in DOCX content. Pass theme to override the preview theme and texts to provide a FilePreviewKitTexts instance. Without explicit texts, English and Simplified Chinese are selected from the current Flutter locale.

Direct parser and view usage

Use the direct APIs only when the parsed model is needed outside the unified preview widget.

import 'dart:typed_data';

import 'package:file_preview_kit/file_preview_kit.dart';
import 'package:flutter/widgets.dart';

Widget buildXlsxPreview(Uint8List bytes) {
  final workbook = XlsxParser().parseBytes(bytes);
  return ExcelPreviewView(workbook: workbook);
}

Widget buildCsvPreview(Uint8List bytes) {
  final workbook = CsvParser().parseBytes(bytes);
  return ExcelPreviewView(workbook: workbook);
}

Widget buildDocxPreview(Uint8List bytes) {
  final document = DocxParser().parseBytes(bytes);
  return DocxPreviewView(document: document);
}

See the example application for file-picker integration.