flutter_drawing_board 0.4.1+3

A Flutter package of drawing board, provides basic drawing tools, canvas operations, and image data acquisition.

example/lib/main.dart

import 'dart:convert';
import 'dart:io';

import 'package:flutter/foundation.dart';
import 'package:flutter/material.dart';
import 'package:flutter/services.dart';
import 'package:flutter_drawing_board/flutter_drawing_board.dart';
import 'package:flutter_drawing_board/paint_contents.dart';
import 'package:flutter_drawing_board/paint_extension.dart';

const Map<String, dynamic> _testLine1 = <String, dynamic>{
  'type': 'StraightLine',
  'startPoint': <String, dynamic>{
    'dx': 68.94337550070736,
    'dy': 62.05980083656557
  },
  'endPoint': <String, dynamic>{
    'dx': 277.1373386828114,
    'dy': 277.32029957032194
  },
  'paint': <String, dynamic>{
    'blendMode': 3,
    'color': 4294198070,
    'filterQuality': 3,
    'invertColors': false,
    'isAntiAlias': false,
    'strokeCap': 1,
    'strokeJoin': 1,
    'strokeWidth': 4.0,
    'style': 1
  }
};

const Map<String, dynamic> _testLine2 = <String, dynamic>{
  'type': 'StraightLine',
  'startPoint': <String, dynamic>{
    'dx': 106.35164817830423,
    'dy': 255.9575653134524
  },
  'endPoint': <String, dynamic>{
    'dx': 292.76034659254094,
    'dy': 92.125586665872
  },
  'paint': <String, dynamic>{
    'blendMode': 3,
    'color': 4294198070,
    'filterQuality': 3,
    'invertColors': false,
    'isAntiAlias': false,
    'strokeCap': 1,
    'strokeJoin': 1,
    'strokeWidth': 4.0,
    'style': 1
  }
};

/// 自定义绘制三角形
class Triangle extends PaintContent {
  Triangle();

  Triangle.data({
    required this.startPoint,
    required this.A,
    required this.B,
    required this.C,
    required Paint paint,
  }) : super.paint(paint);

  factory Triangle.fromJson(Map<String, dynamic> data) {
    return Triangle.data(
      startPoint: jsonToOffset(data['startPoint'] as Map<String, dynamic>),
      A: jsonToOffset(data['A'] as Map<String, dynamic>),
      B: jsonToOffset(data['B'] as Map<String, dynamic>),
      C: jsonToOffset(data['C'] as Map<String, dynamic>),
      paint: jsonToPaint(data['paint'] as Map<String, dynamic>),
    );
  }

  Offset startPoint = Offset.zero;

  Offset A = Offset.zero;
  Offset B = Offset.zero;
  Offset C = Offset.zero;

  @override
  void startDraw(Offset startPoint) => this.startPoint = startPoint;

  @override
  void drawing(Offset nowPoint) {
    A = Offset(
        startPoint.dx + (nowPoint.dx - startPoint.dx) / 2, startPoint.dy);
    B = Offset(startPoint.dx, nowPoint.dy);
    C = nowPoint;
  }

  @override
  void draw(Canvas canvas, Size size, bool deeper) {
    final Path path = Path()
      ..moveTo(A.dx, A.dy)
      ..lineTo(B.dx, B.dy)
      ..lineTo(C.dx, C.dy)
      ..close();

    canvas.drawPath(path, paint);
  }

  @override
  Triangle copy() => Triangle();

  @override
  Map<String, dynamic> toJson() {
    return <String, dynamic>{
      'startPoint': startPoint.toJson(),
      'A': A.toJson(),
      'B': B.toJson(),
      'C': C.toJson(),
      'paint': paint.toJson(),
    };
  }
}

void main() {
  FlutterError.onError = (FlutterErrorDetails details) {
    FlutterError.dumpErrorToConsole(details);
    if (kReleaseMode) {
      exit(1);
    }
  };

  runApp(MyApp());
}

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Drawing Test',
      theme: ThemeData(primarySwatch: Colors.blue),
      home: const MyHomePage(),
    );
  }
}

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

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

class _MyHomePageState extends State<MyHomePage> {
  /// 绘制控制器
  final DrawingController _drawingController = DrawingController();

  @override
  void dispose() {
    _drawingController.dispose();
    super.dispose();
  }

  /// 获取画板数据 `getImageData()`
  Future<void> _getImageData() async {
    final Uint8List? data =
        (await _drawingController.getImageData())?.buffer.asUint8List();
    if (data == null) {
      print('获取图片数据失败');
      return;
    }
    showDialog<void>(
      context: context,
      builder: (BuildContext c) {
        return Material(
          color: Colors.transparent,
          child:
              InkWell(onTap: () => Navigator.pop(c), child: Image.memory(data)),
        );
      },
    );
  }

  /// 获取画板内容 Json `getJsonList()`
  Future<void> _getJson() async {
    showDialog<void>(
      context: context,
      builder: (BuildContext c) {
        return Center(
          child: Material(
            color: Colors.white,
            child: InkWell(
              onTap: () => Navigator.pop(c),
              child: Container(
                constraints:
                    const BoxConstraints(maxWidth: 500, maxHeight: 800),
                padding: const EdgeInsets.all(20.0),
                child: SelectableText(
                  const JsonEncoder.withIndent('  ')
                      .convert(_drawingController.getJsonList()),
                ),
              ),
            ),
          ),
        );
      },
    );
  }

  /// 添加Json测试内容
  void _addTestLine() {
    _drawingController.addContent(StraightLine.fromJson(_testLine1));
    _drawingController
        .addContents(<PaintContent>[StraightLine.fromJson(_testLine2)]);
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      resizeToAvoidBottomInset: false,
      backgroundColor: Colors.grey,
      appBar: AppBar(
        title: const Text('Drawing Test'),
        systemOverlayStyle: SystemUiOverlayStyle.light,
        actions: <Widget>[
          IconButton(
              icon: const Icon(Icons.line_axis), onPressed: _addTestLine),
          IconButton(
              icon: const Icon(Icons.javascript_outlined), onPressed: _getJson),
          IconButton(icon: const Icon(Icons.check), onPressed: _getImageData),
          const SizedBox(width: 40),
        ],
      ),
      body: Column(
        children: <Widget>[
          Expanded(
            child: DrawingBoard(
              // boardPanEnabled: false,
              // boardScaleEnabled: false,
              controller: _drawingController,
              background:
                  Container(width: 400, height: 400, color: Colors.white),
              showDefaultActions: true,
              showDefaultTools: true,
              defaultToolsBuilder: (Type t, _) {
                return DrawingBoard.defaultTools(t, _drawingController)
                  ..insert(
                    1,
                    DefToolItem(
                      icon: Icons.change_history_rounded,
                      isActive: t == Triangle,
                      onTap: () =>
                          _drawingController.setPaintContent = Triangle(),
                    ),
                  );
              },
            ),
          ),
          const Padding(
            padding: EdgeInsets.all(8.0),
            child: SelectableText(
              'https://github.com/xSILENCEx/flutter_drawing_board',
              style: TextStyle(fontSize: 10, color: Colors.white),
            ),
          ),
        ],
      ),
    );
  }
}