PDF Editor Library

A comprehensive Flutter package for PDF annotation and editing with support for drawing, text annotations, shapes, and comments.

Features

• ✅ PDF Viewing: Load and display PDF documents with zoom and pan support
• ✅ Drawing Tools: Free-hand drawing with customizable pen colors and stroke width
• ✅ Text Annotations: Add text overlays with customizable positioning and font size
• ✅ Shape Tools: Insert circles, rectangles, lines, arrows, and triangles
• ✅ Comment System: Add comment annotations with tap-to-place functionality
• ✅ Undo/Redo: Full undo/redo support for all annotation types
• ✅ Page Navigation: Navigate between PDF pages with intuitive controls
• ✅ Export: Save annotated PDFs to device storage
• ✅ Interactive Viewer: Zoom, pan, and scale support with transformation controls

Installation

Add this to your package's pubspec.yaml file:

dependencies:
  file_editor: ^0.0.1

Then run:

flutter pub get

Dependencies

This package relies on the following dependencies:

• pdfx: ^2.9.1 - PDF rendering and document handling
• pdf: ^3.11.3 - PDF generation and manipulation
• flutter_riverpod: ^2.6.1 - State management
• permission_handler: ^12.0.0+1 - Storage permissions
• path_provider: ^2.1.5 - File path management

Quick Start

Basic Usage

import 'package:file_editor/pdf_editor_lib.dart';
import 'package:flutter/material.dart';

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: PdfAnnotator('/path/to/your/pdf/file.pdf'),
    );
  }
}

With Provider Wrapper

import 'package:flutter_riverpod/flutter_riverpod.dart';

void main() {
  runApp(
    ProviderScope(
      child: MyApp(),
    ),
  );
}

API Reference

PdfAnnotator Widget

The main widget for PDF annotation functionality.

Constructor

PdfAnnotator(
  String? filePath, {
  Key? key,
})

Parameters

• filePath: Path to the PDF file to be loaded and annotated

Features Available

1. Drawing Mode: Enable/disable free-hand drawing
2. Pen Color Selection: Choose from red, blue, green, black, or yellow
3. Text Annotations: Add positioned text with customizable size
4. Shape Tools: Insert various geometric shapes
5. Comment System: Add comment annotations at specific positions
6. Page Navigation: Move between PDF pages
7. Undo/Redo: Revert or restore annotation changes
8. Save Functionality: Export annotated PDF

Annotation Types

1. Drawing Annotations

Free-hand drawing with customizable pen properties:

• Colors: Red, Blue, Green, Black, Yellow
• Stroke Width: Adjustable stroke width (default: 3.0)
• Stroke Cap: Rounded line endings

2. Text Annotations

Positioned text overlays with:

• Editable Text: Multi-line text input
• Repositioning: Drag to move text annotations
• Font Size: Adjustable text size
• Color Support: Customizable text colors

3. Shape Annotations

Geometric shapes including:

• Circle: Perfect circles with drag-resize capability
• Rectangle: Rectangles with corner handles
• Line: Straight lines with endpoint controls
• Arrow: Directional arrows
• Triangle: Triangular shapes

4. Comment Annotations

Positioned comment bubbles:

• Tap-to-Place: Click anywhere to add comments
• Comment Dialog: Rich text input for comments
• Visual Indicators: Orange comment icons
• Delete Functionality: Remove comments with delete button

User Interface

Toolbar Features

The top app bar includes:

1. Pen Color Dropdown: Select drawing color
2. Comment Toggle: Enable/disable comment placement mode
3. Draw/Shapes Menu: Access drawing and shape tools
4. Save Button: Export annotated PDF

Navigation Controls

Floating page controls provide:

• Previous/Next Page: Navigate between pages
• Page Counter: Current page / total pages display
• Undo/Redo: Quick access to undo/redo functions

State Management

The library uses Riverpod for state management with the following providers:

• pdfEditorProvider: Main state provider for PDF editor functionality
• Manages document state, annotations, current page, and user interactions

Permissions

The library handles the following permissions automatically:

• Storage Access: For reading PDF files and saving annotated versions
• File System: Access to device storage directories

File Structure

lib/
├── pdf_editor_lib.dart          # Main library export
└── src/
    ├── pdf/
    │   ├── pdf_annotator.dart           # Main PDF annotator widget
    │   ├── pdf_annotator_riverpods.dart # State management
    │   ├── pdf_annotator_state.dart     # State model
    │   ├── comment_annotation.dart      # Comment annotation model
    │   └── PdfEditorWidgetWrapper.dart  # Widget wrapper
    ├── shape/
    │   ├── shape.dart                   # Shape model
    │   └── draggable_resizable_shape.dart # Interactive shape widget
    ├── text_annotation/
    │   ├── text_annotation.dart         # Text annotation model
    │   ├── text_sticker.dart           # Text overlay widget
    │   └── stroke_segment.dart         # Drawing stroke model
    └── utils/
        ├── shape_type.dart              # Shape type enumeration
        ├── string_extension.dart        # String utilities
        ├── permission_request_handler.dart # Permission handling
        └── storage_directory_path.dart  # File path utilities

Examples

Basic PDF Viewer

import 'package:file_editor/pdf_editor_lib.dart';
import 'package:flutter/material.dart';
import 'package:flutter_riverpod/flutter_riverpod.dart';

class BasicPdfViewer extends ConsumerWidget {
  final String pdfPath;

  const BasicPdfViewer({required this.pdfPath, Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context, WidgetRef ref) {
    return Scaffold(
      body: PdfAnnotator(pdfPath),
    );
  }
}

Custom App Integration

class CustomPdfEditor extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'PDF Editor',
      theme: ThemeData(
        primarySwatch: Colors.blue,
        visualDensity: VisualDensity.adaptivePlatformDensity,
      ),
      home: ProviderScope(
        child: PdfAnnotator('/storage/emulated/0/Documents/sample.pdf'),
      ),
    );
  }
}

Troubleshooting

Common Issues

1. PDF Not Loading

   • Ensure the file path is correct and accessible
   • Check file permissions
   • Verify the file is a valid PDF format

2. Annotations Not Saving

   • Confirm storage permissions are granted
   • Check available storage space
   • Ensure write permissions to the target directory

3. Performance Issues

   • Large PDF files may require more memory
   • Consider implementing pagination for very large documents
   • Monitor device memory usage

Error Handling

The library includes built-in error handling for:

• Invalid file paths
• Unsupported file formats
• Permission denied scenarios
• Storage access failures

Contributing

This library is actively being developed. Key areas for contribution:

1. Additional Shape Types: Extend the shape toolkit
2. Advanced Text Formatting: Rich text support
3. Annotation Export: Export annotations to various formats
4. Performance Optimization: Improve rendering for large documents
5. Accessibility: Add screen reader and keyboard navigation support

License

This project is licensed under the terms specified in the LICENSE file.

Changelog

See CHANGELOG.md for a detailed history of changes and updates.

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Note: This library is currently in version 0.0.1 and under active development. Some features may be experimental or subject to change in future releases.