[ Flutter - Preview ] 수학 문제 및 필기 어플++ - 2020 수능 수학 문제

main.dart

import 'dart:ui';
import 'package:flutter/material.dart';

class MathController{}

class Math extends StatelessWidget {
  Math({Key? key}) : super(key: key);
  static const String path = "/math";
  final MathController _mathController = MathController();
  @override
  Widget build(BuildContext context) => MathView(controller: this._mathController);
}

class MathView extends StatefulWidget {
  final MathController controller;
  MathView({Key? key, required this.controller}) : super(key: key);

  @override
  State<MathView> createState() => _MathViewState();
}

class _MathViewState extends State<MathView> {
  List<List<Offset?>> offsets = [<Offset?>[]];
  bool isPainter = false;
  int? selectNumber;
  int pageNumber = 0;

  @override
  Widget build(BuildContext context) => Scaffold(
    appBar: AppBar(
      title: Text("JamesMath"),
      centerTitle: true,
      actions: [
        IconButton(
          icon: Icon(Icons.skip_previous),
          onPressed: this.pageNumber == 0 ? null : () => setState(() => this.pageNumber--)
        ),
        IconButton(
          icon: Icon(Icons.navigate_next),
          onPressed: (){
            setState((){
              this.offsets.add(<Offset?>[]);
              this.pageNumber++;
            });
          }
        ),
      ]
    ),
    floatingActionButton: FloatingActionButton(
      child: Icon(Icons.play_arrow),
      onPressed: this.selectNumber == null ? null : () async{
        setState(() => this.isPainter = false);
        await showDialog(
          context: context,
          builder: (BuildContext context) => AlertDialog(
            title: Text(this.selectNumber == 2 ? "정답 👍" : "🔥 오답, 다시풀어주세요"),
            actions: [
              TextButton(
                child: Text("닫기"),
                onPressed: () => Navigator.of(context).pop()
              ),
              TextButton(
                child: Text("새로 풀기"),
                onPressed: (){
                  setState(() {
                    this.selectNumber = null;
                    this.offsets = [<Offset?>[]];
                    this.pageNumber = 0;
                  });
                  Navigator.of(context).pop();
                }
              )
            ],
          )
        );
      },
    ),
    bottomNavigationBar: BottomAppBar(
      child: Container(
          child: Row(
            children: [
              Expanded(
                child: IconButton(
                  icon: this.isPainter ? Icon(Icons.lock_open_rounded,) : Icon(Icons.lock, color: Colors.red),
                  onPressed: () => setState(() => this.isPainter = !this.isPainter),
                ),
              ),
              Expanded(
                child: IconButton(
                  icon: Icon(Icons.close),
                  onPressed: () => setState(() {
                    this.offsets = [<Offset?>[]];
                    this.pageNumber = 0;
                  }),
                ),
              )
            ],
          )
      ),
    ),
    body: Stack(
      alignment: Alignment.center,
      children: [
        Container(
          child: GestureDetector(
            onPanDown: (details) {
              if(!this.isPainter) return;
              RenderBox _renderBox = context.findRenderObject() as RenderBox;
              Offset _localPosition = _renderBox.globalToLocal(details.globalPosition);
              setState(() {
                this.offsets[this.pageNumber].add(Offset(_localPosition.dx, _localPosition.dy-MediaQuery.of(context).padding.top - kToolbarHeight));
              });
            },
            onPanUpdate: (details) {
              if(!this.isPainter) return;
              RenderBox _renderBox = context.findRenderObject() as RenderBox;
              Offset _localPosition = _renderBox.globalToLocal(details.globalPosition);
              setState(() {
                this.offsets[this.pageNumber].add(Offset(_localPosition.dx, _localPosition.dy-MediaQuery.of(context).padding.top - kToolbarHeight));
              });
            },
            onPanEnd: (details) {
              if(!this.isPainter) return;
              setState(() {
                this.offsets[this.pageNumber].add(null);
              });
            },
            child: CustomPaint(
              painter: MathPainter(this.offsets[this.pageNumber]),
              child: Container(
                child: Column(
                  children: [
                    Container(
                      padding: EdgeInsets.all(30.0),
                      child: Column(
                        crossAxisAlignment: CrossAxisAlignment.start,
                        mainAxisAlignment: MainAxisAlignment.center,
                        children: [
                          Text(
                            "2020 수능 수학(가형 / 홀수형)",
                            style: TextStyle(
                              color: Colors.red
                            )
                          ),
                          Text(
                            "3. 좌표공간의 두 점 A(2,0,1), B(3,2,0)에서 같은 거리에 있는 y축 위의 점의 좌표가 (0, a, 0) 일 때, a의 값은? [2점]",
                            style: TextStyle(
                              fontSize: 20.0
                            ),
                          ),
                        ],
                      ),
                    ),
                    Container(
                      margin: EdgeInsets.symmetric(
                        horizontal: 10.0
                      ),
                      child: Row(
                        children: <int>[1,2,3,4,5].map<Widget>(
                          (int s) => Expanded(
                            child: Container(
                              margin: EdgeInsets.symmetric(
                                horizontal: 4.0
                              ),
                              child: MaterialButton(
                                color: this.selectNumber == s ? Colors.red : Colors.grey[200],
                                child: Text(s.toString()),
                                shape: RoundedRectangleBorder(
                                  borderRadius: BorderRadius.circular(50.0)
                                ),
                                textColor: this.selectNumber == s ? Colors.white : Colors.black,
                                onPressed: () => setState(() => this.selectNumber = s),
                              ),
                            ),
                          )
                        ).toList(),
                      ),
                    ),
                  ],
                )
              ),
            ),
          ),
        ),
        Positioned(
          bottom: 20.0,
          child: Container(
            child: Text(
              "p.${this.pageNumber+1}",
              style: TextStyle(
                color: Colors.grey
              )
            ),
          )
        )
      ],
    )
  );
}

class MathPainter extends CustomPainter {
  final List<Offset?> offsets;

  MathPainter(this.offsets) : super();

  @override
  void paint(Canvas canvas, Size size) {
    final paint = Paint()
      ..color = Colors.deepPurple
      ..isAntiAlias = true
      ..strokeWidth = 3.0;
    if(this.offsets.isEmpty) return;
    for (var i = 0; i < offsets.length; i++) {
      if(offsets[i] != null){
        if (shouldDrawLine(i)) {
          canvas.drawLine(offsets[i]!, offsets[i + 1]!, paint);
        } else if (shouldDrawPoint(i)) {
          canvas.drawPoints(PointMode.points, [offsets[i]!], paint);
        }
      }
    }
  }

  bool shouldDrawPoint(int i) => offsets[i] != null && offsets.length > i + 1 && offsets[i + 1] == null;

  bool shouldDrawLine(int i) => offsets[i] != null && offsets.length > i + 1 && offsets[i + 1] != null;

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