flutter_arrow_path 1.1.1

Draw arrows with Path objects easily. Paths can be composited to add arrows to any curve and draw all at once. Fork of `arrow_path` lib with null safety added.

example/lib/main.dart

import 'dart:ui';

import 'package:arrow_path/flutter_arrow_path.dart';
import 'package:flutter/material.dart';
import 'package:flutter/services.dart';

void main() => runApp(MyApp());

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Arrow Path Example',
      theme: ThemeData(primarySwatch: Colors.blue),
      home: ExampleApp(),
    );
  }
}

class ExampleApp extends StatefulWidget {
  ExampleApp({Key? key}) : super(key: key);

  @override
  _ExampleAppState createState() => _ExampleAppState();
}

class _ExampleAppState extends State<ExampleApp> {
  @override
  void initState() {
    SystemChrome.setPreferredOrientations([
      DeviceOrientation.portraitUp,
      DeviceOrientation.portraitDown,
    ]);
    super.initState();
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: Text('Arrow Path Example')),
      body: Container(
        constraints: BoxConstraints.expand(),
        child: CustomPaint(
          painter: ArrowPainter(),
        ),
      ),
    );
  }
}

class ArrowPainter extends CustomPainter {
  @override
  void paint(Canvas canvas, Size size) {
    TextSpan textSpan;
    TextPainter textPainter;
    Path path;

    // The arrows usually looks better with rounded caps.
    Paint paint = Paint()
      ..color = Colors.black
      ..style = PaintingStyle.stroke
      ..strokeCap = StrokeCap.round
      ..strokeJoin = StrokeJoin.round
      ..strokeWidth = 3.0;

    /// Draw a single arrow.
    path = Path();
    path.moveTo(size.width * 0.25, size.height * 0.10);
    path.relativeCubicTo(0, 0, size.width * 0.25, 50, size.width * 0.5, 0);
    path = ArrowPath.make(path: path);
    canvas.drawPath(path, paint..color = Colors.blue);

    textSpan = TextSpan(
      text: 'Single arrow',
      style: TextStyle(color: Colors.blue),
    );
    textPainter = TextPainter(
      text: textSpan,
      textAlign: TextAlign.center,
      textDirection: TextDirection.ltr,
    );
    textPainter.layout(minWidth: size.width);
    textPainter.paint(canvas, Offset(0, size.height * 0.06));

    /// Draw a double sided arrow.
    path = Path();
    path.moveTo(size.width * 0.25, size.height * 0.2);
    path.relativeCubicTo(0, 0, size.width * 0.25, 50, size.width * 0.5, 0);
    path = ArrowPath.make(path: path, isDoubleSided: true);
    canvas.drawPath(path, paint..color = Colors.cyan);

    textSpan = TextSpan(
      text: 'Double sided arrow',
      style: TextStyle(color: Colors.cyan),
    );
    textPainter = TextPainter(
      text: textSpan,
      textAlign: TextAlign.center,
      textDirection: TextDirection.ltr,
    );
    textPainter.layout(minWidth: size.width);
    textPainter.paint(canvas, Offset(0, size.height * 0.16));

    /// Use complex path.
    path = Path();
    path.moveTo(size.width * 0.25, size.height * 0.3);
    path.relativeCubicTo(0, 0, size.width * 0.25, 50, size.width * 0.5, 50);
    path.relativeCubicTo(0, 0, -size.width * 0.25, 0, -size.width * 0.5, 50);
    path.relativeCubicTo(0, 0, size.width * 0.125, 10, size.width * 0.25, -10);
    path = ArrowPath.make(path: path, isDoubleSided: true);
    canvas.drawPath(path, paint..color = Colors.blue);

    textSpan = TextSpan(
      text: 'Complex path',
      style: TextStyle(color: Colors.blue),
    );
    textPainter = TextPainter(
      text: textSpan,
      textAlign: TextAlign.center,
      textDirection: TextDirection.ltr,
    );
    textPainter.layout(minWidth: size.width);
    textPainter.paint(canvas, Offset(0, size.height * 0.28));

    /// Draw several arrows on the same path.
    path = Path();
    path.moveTo(size.width * 0.25, size.height * 0.53);
    path.relativeCubicTo(0, 0, size.width * 0.25, 50, size.width * 0.5, 50);
    path = ArrowPath.make(path: path);
    path.relativeCubicTo(0, 0, -size.width * 0.25, 0, -size.width * 0.5, 50);
    path = ArrowPath.make(path: path);
    Path subPath = Path();
    subPath.moveTo(size.width * 0.375, size.height * 0.53 + 100);
    subPath.relativeCubicTo(
        0, 0, size.width * 0.125, 10, size.width * 0.25, -10);
    subPath = ArrowPath.make(path: subPath, isDoubleSided: true);
    path.addPath(subPath, Offset.zero);
    canvas.drawPath(path, paint..color = Colors.cyan);

    textSpan = TextSpan(
      text: 'Several arrows on the same path',
      style: TextStyle(color: Colors.cyan),
    );
    textPainter = TextPainter(
      text: textSpan,
      textAlign: TextAlign.center,
      textDirection: TextDirection.ltr,
    );
    textPainter.layout(minWidth: size.width);
    textPainter.paint(canvas, Offset(0, size.height * 0.49));

    /// Adjusted
    path = Path();
    path.moveTo(size.width * 0.1, size.height * 0.8);
    path.relativeCubicTo(0, 0, size.width * 0.3, 50, size.width * 0.25, 75);
    path = ArrowPath.make(path: path, isAdjusted: true);
    canvas.drawPath(path, paint..color = Colors.blue);

    textSpan = TextSpan(
      text: 'Adjusted',
      style: TextStyle(color: Colors.blue),
    );
    textPainter = TextPainter(
      text: textSpan,
      textAlign: TextAlign.left,
      textDirection: TextDirection.ltr,
    );
    textPainter.layout();
    textPainter.paint(canvas, Offset(size.width * 0.2, size.height * 0.77));

    /// Non adjusted.
    path = Path();
    path.moveTo(size.width * 0.6, size.height * 0.8);
    path.relativeCubicTo(0, 0, size.width * 0.3, 50, size.width * 0.25, 75);
    path = ArrowPath.make(path: path, isAdjusted: false);
    canvas.drawPath(path, paint..color = Colors.blue);

    textSpan = TextSpan(
      text: 'Non adjusted',
      style: TextStyle(color: Colors.blue),
    );
    textPainter = TextPainter(
      text: textSpan,
      textAlign: TextAlign.left,
      textDirection: TextDirection.ltr,
    );
    textPainter.layout();
    textPainter.paint(canvas, Offset(size.width * 0.65, size.height * 0.77));
  }

  @override
  bool shouldRepaint(ArrowPainter oldDelegate) => true;
}