pdf_acroform

A Dart/Flutter package for parsing PDF AcroForm fields and displaying interactive form overlays.

Features

• Parse AcroForm fields from PDF documents
• Extract field metadata: name, type, position, default values
• Support for text fields, checkboxes, dropdowns, and more
• Field properties: multiline, read-only, max length, text alignment
• Flutter widget to display PDF with editable form overlays
• Pure Dart parser (works without Flutter)

Installation

Add to your pubspec.yaml:

dependencies:
  pdf_acroform:
    git:
      url: https://github.com/alpaga-dev/pdf_acroform.git

Usage

Parsing PDF form fields (Dart)

import 'package:pdf_acroform/pdf_acroform.dart';

// Parse a PDF file
final parser = await AcroFormParser.fromFile('form.pdf');
final fields = await parser.extractFields();

// List all fields
for (final field in fields) {
  print('${field.name}: ${field.type}');
}

// Extract pre-filled values as a Map
final formData = fields.extractFormData();
print(formData); // {'firstName': 'John', 'newsletter': true, ...}

// Filter fields
final textFields = fields.ofType(PdfFieldType.text);
final page1Fields = fields.forPage(0);

Displaying PDF with form overlays (Flutter)

import 'package:pdf_acroform/pdf_acroform.dart';
import 'package:pdf_acroform/pdf_acroform_viewer.dart';

class MyFormScreen extends StatefulWidget {
  @override
  State<MyFormScreen> createState() => _MyFormScreenState();
}

class _MyFormScreenState extends State<MyFormScreen> {
  List<PdfFormField>? _fields;
  Map<String, dynamic> _formData = {};

  @override
  void initState() {
    super.initState();
    _loadPdf();
  }

  Future<void> _loadPdf() async {
    final parser = await AcroFormParser.fromFile('form.pdf');
    final fields = await parser.extractFields();
    setState(() {
      _fields = fields;
      _formData = fields.extractFormData();
    });
  }

  @override
  Widget build(BuildContext context) {
    if (_fields == null) {
      return const Center(child: CircularProgressIndicator());
    }

    return PdfFormViewer(
      pdfPath: 'form.pdf',
      fields: _fields!,
      formData: _formData,
      readOnlyFields: {'signatureDate', 'referenceNumber'}, // Optional
      onFieldChanged: (name, value) {
        setState(() => _formData[name] = value);
      },
    );
  }
}

Supported field types

Type	Description
text	Single or multiline text input
button	Checkbox or radio button
choice	Dropdown or list selection
signature	Signature field (detected but not editable)

PdfFormViewer options

Parameter	Type	Description
pdfPath	String	Path to the PDF file
fields	List<PdfFormField>	Fields extracted from the PDF
formData	Map<String, dynamic>	Current form values
onFieldChanged	Function(String, dynamic)	Callback when a field value changes
readOnlyFields	Set<String>	Field names to display as read-only (optional)
style	PdfFormStyle	Style configuration for form fields (optional)

The readOnlyFields parameter allows you to make specific fields non-editable at runtime, regardless of their read-only status in the PDF. This is useful for:

• Locking pre-filled fields that shouldn't be modified
• Implementing role-based field permissions
• Creating partial preview modes

Styling form fields

By default, form fields use a PDF-like appearance (yellow background, blue borders) that is independent of your app's theme. You can customize the appearance using PdfFormStyle.

Using your app's theme

To match form fields with your app's theme, use PdfFormStyle.fromTheme():

PdfFormViewer(
  pdfPath: 'form.pdf',
  fields: _fields!,
  formData: _formData,
  style: PdfFormStyle.fromTheme(Theme.of(context)),
  onFieldChanged: (name, value) {
    setState(() => _formData[name] = value);
  },
)

Custom styling

For fine-grained control, create a custom PdfFormStyle:

PdfFormViewer(
  pdfPath: 'form.pdf',
  fields: _fields!,
  formData: _formData,
  style: PdfFormStyle(
    borderRadius: 4,
    borderColor: Colors.grey,
    activeBorderColor: Colors.blue,
    fillColor: Colors.white,
    activeFillColor: Colors.blue.withOpacity(0.1),
    readOnlyFillColor: Colors.grey.withOpacity(0.2),
    textStyle: TextStyle(fontFamily: 'Roboto'),
    cursorColor: Colors.blue,
  ),
  onFieldChanged: (name, value) {
    setState(() => _formData[name] = value);
  },
)

PdfFormStyle properties

Property	Type	Description
borderRadius	double	Corner radius of form fields (default: 2)
borderColor	Color?	Border color (default: semi-transparent blue)
activeBorderColor	Color?	Border color when focused (default: blue)
fillColor	Color?	Background color (default: semi-transparent yellow)
activeFillColor	Color?	Background when focused (default: more opaque yellow)
readOnlyFillColor	Color?	Background for read-only fields (default: grey)
textStyle	TextStyle?	Text style for editable fields
readOnlyTextStyle	TextStyle?	Text style for read-only fields
cursorColor	Color?	Cursor color (default: blue)
selectionColor	Color?	Text selection color (default: light blue)
checkColor	Color?	Checkmark color in checkboxes (default: blue)
checkedFillColor	Color?	Background color for checked checkboxes (default: semi-transparent blue)

Field properties

The parser extracts the following properties when available:

• name - Fully qualified field name
• type - Field type (text, button, choice, signature)
• rect - Position and dimensions on the page
• pageIndex - Zero-based page number
• defaultValue - Pre-filled value
• isMultiline - Whether text field supports multiple lines
• isReadOnly - Whether field is editable
• maxLength - Maximum character count
• alignment - Text alignment (left, center, right)
• options - Available choices for dropdown fields

Troubleshooting

Unwanted scroll when focusing text fields

When tapping on a text field, you may experience unwanted scrolling behavior as the keyboard appears. This is caused by Flutter's default behavior of resizing the scaffold body to accommodate the keyboard.

To fix this, set resizeToAvoidBottomInset: false on your Scaffold:

Scaffold(
  resizeToAvoidBottomInset: false,
  body: PdfFormViewer(
    // ...
  ),
)

Similarly, if your widget tree includes a SafeArea, it may also cause unexpected scroll behavior. Consider removing it or adjusting your layout accordingly.

Example app

See the example/ directory for a complete demo application.

cd example
flutter run

License

MIT