ohthatsa_old/lib/pages/practice/instructions/YearInstructionPage.dart

import 'package:flutter/cupertino.dart';
import 'package:flutter/material.dart';
import 'package:numberpicker/numberpicker.dart';

import 'package:ohthatsa/other/AppDrawer.dart';
import 'package:ohthatsa/util/DayCalculator.dart';
import 'package:term_glyph/term_glyph.dart' as glyph;

class YearInstructionPage extends StatefulWidget {
  @override
  _YearInstructionPageState createState() => _YearInstructionPageState();
}

class _YearInstructionPageState extends State<YearInstructionPage> {
  int year;
  int yy;
  String centuriesString;
  String yyString;
  double yyDiv4;
  int yyDiv4Floored;
  int yearValue;

  @override
  void initState(){
    super.initState();
    this.setYearValues(DateTime.now().year);
  }
  void setYearValues(newYear){
    year = newYear;
    yy = year % 100;
    centuriesString = (year ~/ 100).toString();
    yyString = year.toString().substring(2);
    yyDiv4 = yy / 4;
    yyDiv4Floored = yyDiv4.floor();
    yearValue = DayCalculator.getYearValue(year);

    setState(() {});
  }
  static const formulaStyle = TextStyle(
      fontSize: 20
  );
  static const formulaStyleU = TextStyle(
      fontSize: 20,
      decoration: TextDecoration.underline
  );
  static const YYStyle = TextStyle(
      color: Colors.green,
      fontSize: 20
  );
  static const YYStyleU = TextStyle(
      color: Colors.green,
      fontSize: 20,
      decoration: TextDecoration.underline
  );
  static const pageNum = TextStyle(
      color: Colors.grey,
      fontSize: 20
  );
  static const pageNumCurrent = TextStyle(
      color: Colors.blue,
      fontSize: 20
  );
  @override
  Widget build(BuildContext context) {
    return Scaffold(
        drawer: AppDrawer(),
        appBar: AppBar(
            title: Text("Year Instructions")
        ),
        body: PageView(
            children: <Widget>[
              Container(
                  padding: EdgeInsets.fromLTRB(0, 50, 0, 10),
                  child: Column(
                    mainAxisAlignment: MainAxisAlignment.center,
                    crossAxisAlignment: CrossAxisAlignment.center,
                    children: <Widget>[
                      Text(
                          "Take only the last two digits: ",
                          style: TextStyle(fontSize: 25)
                      ),
                      Row(
                        mainAxisAlignment: MainAxisAlignment.center,
                        children: <Widget>[
                          Text(
                              "YY",
                              style: TextStyle(
                                  color: Colors.grey,
                                  fontSize: 25
                              )
                          ),
                          Text(
                              "YY",
                              style: YYStyle
                          )
                        ],
                      ),
                      Text(
                          "Calculate:",
                          style: TextStyle(fontSize: 25)
                      ),
                      Row(
                        mainAxisAlignment: MainAxisAlignment.center,
                        children: <Widget>[
                          Text(
                            "(",
                            style: formulaStyle,
                          ),
                          Text(
                              "YY",
                              style: YYStyle
                          ),
                          Text(
                              " + floor(",
                              style: formulaStyle
                          ),
                          Text(
                              "YY",
                              style: YYStyle
                          ),
                          Text(
                              " / 4)) % 7",
                              style: formulaStyle
                          ),
                        ],
                      ),
                      Spacer(),
                      Row(
                        mainAxisAlignment: MainAxisAlignment.center,
                        children: <Widget>[
                          Text("1", style: pageNumCurrent),
                          Text(" - ", style: pageNum),
                          Text("2", style: pageNum),
                        ],
                      )
                    ],
                  )
              ),
              Container(
                  padding: EdgeInsets.fromLTRB(0, 0, 0, 10),
                  child: Column(
                      mainAxisAlignment: MainAxisAlignment.center,
                      crossAxisAlignment: CrossAxisAlignment.center,
                      children: <Widget>[
                        NumberPicker.integer(
                            initialValue: year,
                            minValue: 1700,
                            maxValue: 2399,
                            onChanged: (newYear) => this.setYearValues(newYear)
                        ),
                        Row(
                          mainAxisAlignment: MainAxisAlignment.center,
                          children: <Widget>[
                            Text("For ", style: formulaStyle),
                            Text(centuriesString, style: formulaStyle),
                            Text(year.toString().substring(2), style: YYStyle),
                            Text(" our formula becomes: ", style: formulaStyle),
                          ],
                        ),
                        Row(
                          mainAxisAlignment: MainAxisAlignment.center,
                          children: <Widget>[
                            Text("(", style: formulaStyle),
                            Text(yyString, style: YYStyle),
                            Text(" + floor(", style: formulaStyle),
                            Text(yyString, style: YYStyleU),
                            Text(" / 4", style: formulaStyleU),
                            Text(")) % 7", style: formulaStyle),
                          ],
                        ),
                        Text(glyph.unicodeGlyphs.downArrow, style: TextStyle(fontSize: 15)),
                        Row(
                          mainAxisAlignment: MainAxisAlignment.center,
                          children: <Widget>[
                            Text("(", style: formulaStyle),
                            Text(yyString, style: YYStyle),
                            Text(" + ", style: formulaStyle),
                            Text("floor(" + yyDiv4.toString() + ")", style: formulaStyleU),
                            Text(") % 7", style: formulaStyle),
                          ],
                        ),
                        Text(glyph.unicodeGlyphs.downArrow, style: TextStyle(fontSize: 15)),
                        Row(
                          mainAxisAlignment: MainAxisAlignment.center,
                          children: <Widget>[
                            Text("(", style: formulaStyleU),
                            Text(yyString, style: YYStyleU),
                            Text(" + " + yyDiv4Floored.toString() + ")", style: formulaStyleU),
                            Text(" % 7", style: formulaStyle),
                          ],
                        ),
                        Text(glyph.unicodeGlyphs.downArrow, style: TextStyle(fontSize: 15)),
                        Row(
                          mainAxisAlignment: MainAxisAlignment.center,
                          children: <Widget>[
                            Text((yy + yyDiv4Floored).toString(), style: formulaStyleU),
                            Text(" % 7", style: formulaStyleU),
                          ],
                        ),
                        Text(glyph.unicodeGlyphs.downArrow, style: TextStyle(fontSize: 15)),
                        Row(
                          mainAxisAlignment: MainAxisAlignment.center,
                          children: <Widget>[
                            Text("So the year value of " + year.toString() + " is: ", style: formulaStyle),
                            Text(yearValue.toString(), style: formulaStyleU),
                          ],
                        ),
                        Spacer(),
                        Row(
                          mainAxisAlignment: MainAxisAlignment.center,
                          children: <Widget>[
                            Text("1", style: pageNum),
                            Text(" - ", style: pageNum),
                            Text("2", style: pageNumCurrent),
                          ],
                        )
                      ]
                  )
              )
            ]
        )
    );
  }
}