signature #

A Flutter plugin providing performance optimized signature canvas with ability to set custom style, boundaries and initial state. This is native flutter implementation, so it supports all platforms.

Why #

In time of creation of this plugin, there was no available solution that had:

• required performance on wide range of devices
• ability to set canvas boundaries
• ability to initialize using previously saved state

Migration to 5.0.0+ #

• This version no longer wraps Signature in Expanded widget if you are using it without specifying dimensions
• This removes error Incorrect use of ParentDataWidget, see this issue for more information.
• If you are passing dimensions to widget, you do not have to change anything.
• If you are using widget without dimensions inside Row, Column or Flex widgets, you have to wrap Signature inside Expanded yourself.
• If you are using widget without dimensions, but not inside mentioned widgets you do not have change anything and error should dissapear from your logs :)

Usage #

To use this plugin, add signature as a dependency in your pubspec.yaml file.

Example #

Take a look at our example project as well: Signature Demo

// IMPORT PACKAGE
import 'package:signature/signature.dart';

// Initialise a controller. It will contains signature points, stroke width and pen color.
// It will allow you to interact with the widget
final SignatureController _controller = SignatureController(
    penStrokeWidth: 5,
    penColor: Colors.red,
    exportBackgroundColor: Colors.blue,
);

// INITIALIZE. RESULT IS A WIDGET, SO IT CAN BE DIRECTLY USED IN BUILD METHOD 
var _signatureCanvas = Signature(
  controller: _controller,
  width: 300,
  height: 300,
  backgroundColor: Colors.lightBlueAccent,
);

// CLEAR CANVAS
_controller.clear();

// EXPORT BYTES AS PNG
// The exported image will be limited to the drawn area
_controller.toPngBytes();

// isEmpty/isNotEmpty CAN BE USED TO CHECK IF SIGNATURE HAS BEEN PROVIDED
_controller.isNotEmpty; //true if signature has been provided
_controller.isEmpty; //true if signature has NOT been provided

// EXPORT POINTS (2D POINTS ROUGHLY REPRESENTING WHAT IS VISIBLE ON CANVAS)
var exportedPoints = _controller.points;

//EXPORTED POINTS CAN BE USED TO INITIALIZE PREVIOUS CONTROLLER
final SignatureController _controller = SignatureController(points: exportedPoints);

//DONT FORGET TO DISPOSE IT IN THE `dispose()` METHOD OF STATEFUL WIDGETS
@override
void dispose() {
  _controller.dispose();
  super.dispose();
}

Contribution and Support #

• Contributions are welcome!
• If you want to contribute code please create a PR
• If you find a bug or want a feature, please fill an issue