flutter_mask_painter

A Flutter widget for drawing and exporting mask layers (black and white) on top of images. Perfect for image editing, segmentation, and annotation tasks.

🚀 Use Cases

• AI-powered photo editing: Feed user-generated masks into inpainting, background removal, or other generative AI services
• Selective editing: Apply filters, blurs, or color adjustments only on masked areas
• Creative tools: Build custom drawing or editing apps with masking support

✨ Features

• Draw mask with adjustable brush size
• Undo & Redo
• Export mask as PNG
• Touch-friendly, responsive UI
• Real-time mask preview
• Save mask to file
• Professional controls and smooth drawing

Screenshots

  

Getting Started

Add to your pubspec.yaml:

dependencies:
	flutter_mask_painter: ^1.0.1

Usage

Import the package and use the MaskPainterWidget:

import 'package:flutter_mask_painter/flutter_mask_painter.dart';
import 'package:image_picker/image_picker.dart';

// ...

MaskPainterWidget(
	backgroundImage: yourXFileImage, // XFile from image_picker
	onMaskSaved: (maskFile) {
		// Do something with the saved mask (XFile)
	},
)

Advanced: Using a Controller

For programmatic control, use a MaskPainterController. This allows you to:

• Undo/redo strokes
• Clear all strokes
• Change brush size
• Change mask/background color
• Export the mask as a PNG file
• Listen for changes (with addListener)

Example

final controller = MaskPainterController();

MaskPainterWidget(
	backgroundImage: yourXFileImage,
	controller: controller,
)

// Undo last stroke
controller.undo();

// Redo last undone stroke
controller.redo();

// Clear all strokes
controller.clear();

// Change brush size
controller.setBrushSize(40.0);

// Export the mask 
final maskFile = await controller.saveMask();

// Listen for changes
controller.addListener(() {
	// React to changes (e.g., update UI)
});

See the example/ directory for a complete demo app.

Example

Run the example app:

cd example
flutter run

License

BSD 3-Clause License. See LICENSE for details.