universal_file_previewer #

Preview 50+ file formats in Flutter with zero heavy dependencies.
Uses pure Dart for text-based formats and native platform channels for PDF, video, and audio.

✨ Supported Formats #

🚀 Installation #

dependencies:
  universal_file_previewer: ^0.1.0

📱 Quick Start #

Full-screen preview page #

import 'package:universal_file_previewer/universal_file_previewer.dart';

// One line — opens full-screen preview with toolbar
FilePreviewPage.open(context, file: File('/path/to/document.pdf'));

Inline widget #

FilePreviewWidget(
  file: File('/path/to/file.md'),
  config: PreviewConfig(
    showToolbar: false,
    enableZoom: true,
    codeTheme: CodeTheme.dracula,
  ),
  onTypeDetected: (type) => print('Detected: $type'),
)

With controller (PDF page navigation) #

final controller = PreviewController();

// Widget
FilePreviewWidget(
  file: myPdfFile,
  controller: controller,
)

// Control programmatically
controller.nextPage();
controller.previousPage();
controller.goToPage(5);
controller.zoomIn();
controller.zoomOut();

Detect file type only #

final type = await FileDetector.detect(File('/path/to/file'));
print(type); // FileType.pdf

// From bytes
final type = FileDetector.detectFromBytes(bytes, fileName: 'doc.pdf');

⚙️ Configuration #

PreviewConfig(
  showToolbar: true,          // Show AppBar (in FilePreviewPage)
  showFileInfo: true,         // Show info button in toolbar
  enableZoom: true,           // Pinch-to-zoom for images & PDF
  backgroundColor: Colors.black,
  codeTheme: CodeTheme.dark,  // dark | light | dracula | monokai
  maxTextFileSizeBytes: 5 * 1024 * 1024,  // 5 MB limit for text files
  errorBuilder: (err) => MyErrorWidget(err),
  loadingBuilder: () => MyLoadingWidget(),
)

🏗️ Architecture #

FilePreviewWidget
  │
  ├── FileDetector          ← Magic bytes + extension fallback
  │     └── Pure Dart, reads first 16 bytes
  │
  ├── ImageRenderer         ← Flutter Image.file + InteractiveViewer
  ├── SvgRenderer           ← Pure Dart SVG content display
  ├── HeicRenderer          ← Platform channel → JPEG conversion
  │
  ├── PdfRenderer           ← Platform channel (PDFKit / PdfRenderer API)
  │
  ├── VideoRenderer         ← Platform channel (AVPlayer / ExoPlayer)
  ├── AudioRenderer         ← Platform channel + animated waveform UI
  │
  ├── TextRenderer          ← Pure Dart, SelectableText
  ├── MarkdownRenderer      ← Pure Dart parser, no packages
  ├── JsonRenderer          ← Pure Dart collapsible tree
  ├── CsvRenderer           ← Pure Dart DataTable
  ├── CodeRenderer          ← Pure Dart syntax tokenizer
  │
  ├── ZipRenderer           ← Pure Dart ZIP spec parser (browsable tree)
  │
  └── FallbackRenderer      ← File metadata (name, size, type, date)

📦 Dependencies #

dependencies:
  flutter:
    sdk: flutter
  # That's it. Zero external packages.

🔌 Platform Requirements #

Android

• minSdkVersion 21 (PDF rendering requires API 21+)
• HEIC support requires Android 9+ (API 28+)

iOS

• iOS 11.0+
• PDFKit available since iOS 11

Add to android/app/build.gradle:

android {
    defaultConfig {
        minSdkVersion 21
    }
}

🗺️ Roadmap #

• ✅ Image rendering (JPG, PNG, GIF, WebP, BMP)
• ✅ SVG display
• ✅ PDF rendering (platform channel)
• ✅ Video thumbnail + metadata
• ✅ Audio player UI with waveform
• ✅ Markdown renderer (pure Dart)
• ✅ JSON tree viewer (pure Dart)
• ✅ CSV table renderer (pure Dart)
• ✅ Syntax highlighted code viewer (pure Dart)
• ✅ ZIP archive browser (pure Dart)
• ✅ HEIC conversion (platform channel)
• ❌ DOCX → HTML conversion (pure Dart XML parser)
• ❌ XLSX spreadsheet renderer (pure Dart)
• ❌ PPTX slide viewer
• ❌ 3D model viewer (GLB/OBJ)
• ❌ RAR/7Z archive support
• ❌ Thumbnail generation API

🤝 Contributing #

PRs welcome! Please read CONTRIBUTING.md first.

git clone https://github.com/Naimish-Kumar/universal_file_previewer
cd universal_file_previewer
flutter pub get
cd example && flutter run

📄 License #

MIT License — see LICENSE for details.