rough_notation 0.0.1

Create animated, hand-drawn-style annotations on widgets using Flutter’s CustomPainter. Inspired by the Rough Notation JS library.

RoughNotation Flutter

A lightweight Flutter package to create animated, hand-drawn-style annotations on widgets.

This package recreates the original Rough Notation experience created by Preet Shihn and the contributors.

It uses Flutter’s CustomPainter to render the annotations, supporting config options for styling and animation — including manual triggers, sequencing via groups, and autoplay.

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🌐 Playground

See the landing page which has the complete showcase: 👉 roughnotation-flutter.web.app

It showcases all use cases, animation types, groupings, styling controls, and more — all built with Flutter Web.

Explore source in the playground/ folder.

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✨ Features

• Hand-drawn-style annotations
• Built-in styles:
  • Underline
  • Box
  • Circle
  • Highlight
  • Strike-through
  • Crossed-off
  • Bracket
• Supports:
  • Autoplay animation
  • Manual triggers
  • Group-based sequencing
  • WidgetSpan for rich text use

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📦 Installation

flutter pub add rough_notation

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🚀 Usage

Basic Annotation

RoughUnderlineAnnotation(
  child: Text('Flutter is fun!'),
)

With Controller (Manual Trigger)

final controller = RoughAnnotationController();

RoughBoxAnnotation(
  controller: controller,
  child: Text('Boxed text'),
);

// Manually trigger
controller.show();

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🧹 RichText with WidgetSpan

SelectableText.rich(
  TextSpan(
    text: 'Create a ',
    children: [
      WidgetSpan(
        alignment: PlaceholderAlignment.baseline,
        baseline: TextBaseline.alphabetic,
        child: RoughUnderlineAnnotation(
          child: Text('underline'),
        ),
      ),
      TextSpan(text: ' on a span.'),
    ],
  ),
);

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🔄 Grouped Annotations

Use group and sequence to define a group and control animation order.

RoughUnderlineAnnotation(
  group: 'intro',
  sequence: 1,
  child: Text('Step 1'),
);

RoughBoxAnnotation(
  group: 'intro',
  sequence: 2,
  child: Text('Step 2'),
);

// Trigger animation
RoughAnnotationRegistry.showGroup('intro');

Autoplay a Group on Widget Init

@override
void initState() {
  super.initState();
  RoughAnnotationRegistry.markGroupForAutoStart('groupName');
}

✅ Note:

• It doesn't matter where widgets are in the widget tree — grouped annotations can live inside deeply nested widgets or even different build scopes. The registry handles sequencing regardless of position.
• From Flutter 3.16+, deferred or conditionally built widgets (e.g., in a ListView.builder) won’t throw errors but will skip animations until built.

Optional:

RoughAnnotationRegistry.showGroup(
  'intro',
  delayBetween: Duration(milliseconds: 300),
);

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⚠️ Potential Pitfalls & Edge Cases

• Delays & Durations: Group sequencing introduces its own delays between elements. Avoid adding large delay values on individual annotations if part of a group.
• Controllers & Autoplay: If using RoughAnnotationController(autoPlay: true), ensure the widget is built first. Internally, we use addPostFrameCallback to delay the trigger.
• Multiple Controllers: You can reuse the same controller for multiple widgets, but only one annotation may render if others haven't mounted yet.
• Lazy Lists / Builders: Widgets in a ListView.builder or similar builders that are not yet mounted will not animate. No crash, but no effect either.
• Visual Misalignments: Styling mismatches may occur across platforms. Future updates will improve drawing precision and painter logic.

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🧠 What's Next

We’re aiming to improve:

• Core painter logic for smoother lines and curves (lib/src/painters)
• Extend features and stability of annotation widgets (lib/src/annotations)
• Also the controllers & grouped behaviour (lib/src/controllers)

The original JS library uses roughjs. Although there's a Flutter version (rough), it’s outdated and Dart 3 incompatible.

We’re considering reviving or reimplementing it in parts. All contributions are welcome!

If you're looking to contribute, ideal places to start are:

• lib/src/painters/
• lib/src/annotations/

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🙏❤️ Acknowledgements

This Flutter package is heavily inspired by the original Rough Notation JS library.

We acknowledge the original creators and contributors of the JS library — including design, animation logic, and documentation.

We are grateful for the coder’s community and the support of open-source enthusiasts everywhere.

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📄 License

MIT

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🤝 Contributions

Pull requests are welcome. Let’s make annotations ✏️ in Flutter fun and beautiful.