Mouse wheel scrolling on Windows not precise

I solved it，Related to this：https://github.com/flutter/flutter/issues/119500. First localize flutter_picker: 2.1.0, just copy the four files in the lib directory to your project, and then replace the code of the picker.dart file with the following code： import 'package:flutter/cupertino.dart'; import 'package:flutter/foundation.dart'; import 'package:flutter/gestures.dart'; import 'package:flutter/material.dart'; import 'package:flutter/material.dart' as Dialog; import 'dart:async'; import 'picker_localizations.dart';

/// Picker selected callback. typedef PickerSelectedCallback = void Function( Picker picker, int index, List selected);

/// Picker confirm callback. typedef PickerConfirmCallback = void Function( Picker picker, List selected);

/// Picker confirm before callback. typedef PickerConfirmBeforeCallback = Future Function( Picker picker, List selected);

/// Picker value format callback. typedef PickerValueFormat = String Function(T value);

/// Picker widget builder typedef PickerWidgetBuilder = Widget Function( BuildContext context, Widget pickerWidget);

/// Picker build item, If 'null' is returned, the default build is used typedef PickerItemBuilder = Widget? Function(BuildContext context, String? text, Widget? child, bool selected, int col, int index);

/// Picker class Picker { static const double DefaultTextSize = 18.0;

/// Index of currently selected items late List selecteds;

/// Picker adapter, Used to provide data and generate widgets late PickerAdapter adapter;

/// insert separator before picker columns final List? delimiter;

final VoidCallback? onCancel; final PickerSelectedCallback? onSelect; final PickerConfirmCallback? onConfirm; final PickerConfirmBeforeCallback? onConfirmBefore;

/// When the previous level selection changes, scroll the child to the first item. final changeToFirst;

/// Specify flex for each column final List? columnFlex;

final Widget? title; final Widget? cancel; final Widget? confirm; final String? cancelText; final String? confirmText;

final double height;

/// Height of list item final double itemExtent;

final TextStyle? textStyle, cancelTextStyle, confirmTextStyle, selectedTextStyle; final TextAlign textAlign; final IconThemeData? selectedIconTheme;

/// Text scaling factor final double? textScaleFactor;

final EdgeInsetsGeometry? columnPadding; final Color? backgroundColor, headerColor, containerColor;

/// Hide head final bool hideHeader;

/// Show pickers in reversed order final bool reversedOrder;

/// Generate a custom header， [hideHeader] = true final WidgetBuilder? builderHeader;

/// Generate a custom item widget, If 'null' is returned, the default builder is used final PickerItemBuilder? onBuilderItem;

/// List item loop final bool looping;

/// Delay generation for smoother animation, This is the number of milliseconds to wait. It is recommended to > = 200 final int smooth;

final Widget? footer;

/// A widget overlaid on the picker to highlight the currently selected entry. final Widget selectionOverlay;

final Decoration? headerDecoration;

final double magnification; final double diameterRatio; final double squeeze;

final bool printDebug;

Widget? _widget; PickerWidgetState? _state;

Picker( {required this.adapter, this.delimiter, List? selecteds, this.height = 150.0, this.itemExtent = 28.0, this.columnPadding, this.textStyle, this.cancelTextStyle, this.confirmTextStyle, this.selectedTextStyle, this.selectedIconTheme, this.textAlign = TextAlign.start, this.textScaleFactor, this.title, this.cancel, this.confirm, this.cancelText, this.confirmText, this.backgroundColor, this.containerColor, this.headerColor, this.builderHeader, this.changeToFirst = false, this.hideHeader = false, this.looping = false, this.reversedOrder = false, this.headerDecoration, this.columnFlex, this.footer, this.smooth = 0, this.magnification = 1.0, this.diameterRatio = 1.1, this.squeeze = 1.45, this.selectionOverlay = const CupertinoPickerDefaultSelectionOverlay(), this.onBuilderItem, this.onCancel, this.onSelect, this.onConfirmBefore, this.onConfirm, this.printDebug = false}) { this.selecteds = selecteds == null ? [] : selecteds; }

Widget? get widget => _widget; PickerWidgetState? get state => _state; int _maxLevel = 1;

/// 生成picker控件 /// /// Build picker control Widget makePicker([ThemeData? themeData, bool isModal = false, Key? key]) { _maxLevel = adapter.maxLevel; adapter.picker = this; adapter.initSelects(); _widget = PickerWidget( key: key ?? ValueKey(this), child: _PickerWidget(picker: this, themeData: themeData, isModal: isModal), data: this, ); return _widget!; }

/// show picker bottom sheet void show( ScaffoldState state, { ThemeData? themeData, Color? backgroundColor, PickerWidgetBuilder? builder, }) { state.showBottomSheet((BuildContext context) { final picker = makePicker(themeData); return builder == null ? picker : builder(context, picker); }, backgroundColor: backgroundColor); }

/// show picker bottom sheet void showBottomSheet( BuildContext context, { ThemeData? themeData, Color? backgroundColor, PickerWidgetBuilder? builder, }) { Scaffold.of(context).showBottomSheet((BuildContext context) { final picker = makePicker(themeData); return builder == null ? picker : builder(context, picker); }, backgroundColor: backgroundColor); }

/// Display modal picker Future<T?> showModal(BuildContext context, {ThemeData? themeData, bool isScrollControlled = false, bool useRootNavigator = false, Color? backgroundColor, PickerWidgetBuilder? builder}) async { return await showModalBottomSheet( context: context, //state.context, isScrollControlled: isScrollControlled, useRootNavigator: useRootNavigator, backgroundColor: backgroundColor, builder: (BuildContext context) { final picker = makePicker(themeData, true); return builder == null ? picker : builder(context, picker); }); }

/// show dialog picker Future<List?> showDialog(BuildContext context, {bool barrierDismissible = true, Color? backgroundColor, PickerWidgetBuilder? builder, Key? key}) { return Dialog.showDialog<List>( context: context, barrierDismissible: barrierDismissible, builder: (BuildContext context) { final actions = []; final theme = Theme.of(context); final _cancel = PickerWidgetState._buildButton( context, cancelText, cancel, cancelTextStyle, true, theme, () { Navigator.pop<List>(context, null); if (onCancel != null) { onCancel!(); } }); if (_cancel != null) { actions.add(_cancel); } final _confirm = PickerWidgetState._buildButton( context, confirmText, confirm, confirmTextStyle, false, theme, () async { if (onConfirmBefore != null && !(await onConfirmBefore!(this, selecteds))) { return; // Cancel; } Navigator.pop<List>(context, selecteds); if (onConfirm != null) { onConfirm!(this, selecteds); } }); if (_confirm != null) { actions.add(_confirm); } return AlertDialog( key: key ?? Key('picker-dialog'), title: title, backgroundColor: backgroundColor, actions: actions, content: builder == null ? makePicker(theme) : builder(context, makePicker(theme)), ); }); }

/// 获取当前选择的值 /// Get the value of the current selection List getSelectedValues() { return adapter.getSelectedValues(); }

/// 取消 void doCancel(BuildContext context) { Navigator.of(context).pop<List>(null); if (onCancel != null) onCancel!(); _widget = null; }

/// 确定 void doConfirm(BuildContext context) async { if (onConfirmBefore != null && !(await onConfirmBefore!(this, selecteds))) { return; // Cancel; } Navigator.of(context).pop<List>(selecteds); if (onConfirm != null) onConfirm!(this, selecteds); _widget = null; }

/// 弹制更新指定列的内容 /// 当 onSelect 事件中，修改了当前列前面的列的内容时，可以调用此方法来更新显示 void updateColumn(int index, [bool all = false]) { if (all) { _state?.update(); return; } if (_state?._keys[index] != null) { adapter.setColumn(index - 1); _state?._keys[index]!(() => null); } }

static ButtonStyle _getButtonStyle(ButtonThemeData? theme, [isCancelButton = false]) => TextButton.styleFrom( minimumSize: Size(theme?.minWidth ?? 0.0, 42), textStyle: TextStyle( fontSize: Picker.DefaultTextSize, color: isCancelButton ? null : theme?.colorScheme?.secondary, ), padding: theme?.padding); }

/// 分隔符 class PickerDelimiter { final Widget? child; final int column; PickerDelimiter({required this.child, this.column = 1}); }

/// picker data list item class PickerItem { /// 显示内容 final Widget? text;

/// 数据值 final T? value;

/// 子项 final List<PickerItem>? children;

PickerItem({this.text, this.value, this.children}); }

class PickerWidget extends InheritedWidget { final Picker data; const PickerWidget({Key? key, required this.data, required Widget child}) : super(key: key, child: child); @override bool updateShouldNotify(covariant PickerWidget oldWidget) => oldWidget.data != data;

static PickerWidget of(BuildContext context) { return context.dependOnInheritedWidgetOfExactType() as PickerWidget; } }

class _PickerWidget extends StatefulWidget { final Picker picker; final ThemeData? themeData; final bool isModal; _PickerWidget( {Key? key, required this.picker, this.themeData, required this.isModal}) : super(key: key);

@override PickerWidgetState createState() => PickerWidgetState(picker: this.picker, themeData: this.themeData); }

class PickerWidgetState extends State<_PickerWidget> { final Picker picker; final ThemeData? themeData; PickerWidgetState({required this.picker, this.themeData});

ThemeData? theme; final List scrollController = []; final List<StateSetter?> _keys = [];

@override void initState() { super.initState(); picker._state = this; picker.adapter.doShow();

if (scrollController.length == 0) {
  for (int i = 0; i < picker._maxLevel; i++) {
    scrollController
        .add(FixedExtentScrollController(initialItem: picker.selecteds[i]));
    _keys.add(null);
  }
}

}

void update() { setState(() {}); }

// var ref = 0; @override Widget build(BuildContext context) { // print("picker build ${ref++}"); theme = themeData ?? Theme.of(context);

if (_wait && picker.smooth > 0) {
  Future.delayed(Duration(milliseconds: picker.smooth), () {
    if (!_wait) return;
    setState(() {
      _wait = false;
    });
  });
} else
  _wait = false;

final _body = <Widget>[];
if (!picker.hideHeader) {
  if (picker.builderHeader != null) {
    _body.add(picker.headerDecoration == null
        ? picker.builderHeader!(context)
        : DecoratedBox(
            child: picker.builderHeader!(context),
            decoration: picker.headerDecoration!));
  } else {
    _body.add(DecoratedBox(
      child: Row(
        children: _buildHeaderViews(context),
      ),
      decoration: picker.headerDecoration ??
          BoxDecoration(
            border: Border(
              top: BorderSide(color: theme!.dividerColor, width: 0.5),
              bottom: BorderSide(color: theme!.dividerColor, width: 0.5),
            ),
            color: picker.headerColor == null
                ? theme?.bottomAppBarTheme.color
                : picker.headerColor,
          ),
    ));
  }
}

_body.add(_wait
    ? Row(
        mainAxisAlignment: MainAxisAlignment.spaceBetween,
        children: _buildViews(),
      )
    : AnimatedSwitcher(
        duration: Duration(milliseconds: 300),
        child: Row(
          mainAxisAlignment: MainAxisAlignment.spaceBetween,
          children: _buildViews(),
        ),
      ));

if (picker.footer != null) _body.add(picker.footer!);
Widget v = Column(
  mainAxisSize: MainAxisSize.min,
  children: _body,
);
if (widget.isModal) {
  return GestureDetector(
    onTap: () {},
    child: v,
  );
}
return v;

}

List? _headerItems;

List _buildHeaderViews(BuildContext context) { if (_headerItems != null) { return _headerItems!; } if (theme == null) theme = Theme.of(context); List items = [];

final _cancel = _buildButton(context, picker.cancelText, picker.cancel,
    picker.cancelTextStyle, true, theme, () => picker.doCancel(context));
if (_cancel != null) {
  items.add(_cancel);
}

items.add(Expanded(
  child: picker.title == null
      ? SizedBox()
      : DefaultTextStyle(
          style: (theme!.textTheme.headline6 ?? theme!.textTheme.titleLarge)
                  ?.copyWith(
                fontSize: Picker.DefaultTextSize,
              ) ??
              TextStyle(fontSize: Picker.DefaultTextSize),
          textAlign: TextAlign.center,
          overflow: TextOverflow.ellipsis,
          child: picker.title!),
));

final _confirm = _buildButton(context, picker.confirmText, picker.confirm,
    picker.confirmTextStyle, false, theme, () => picker.doConfirm(context));
if (_confirm != null) {
  items.add(_confirm);
}

_headerItems = items;
return items;

}

static Widget? _buildButton( BuildContext context, String? text, Widget? widget, TextStyle? textStyle, bool isCancel, ThemeData? theme, VoidCallback? onPressed) { if (widget == null) { String? _txt = text ?? (isCancel ? PickerLocalizations.of(context).cancelText : PickerLocalizations.of(context).confirmText); if (_txt == null || _txt.isEmpty) { return null; } return TextButton( style: Picker._getButtonStyle(ButtonTheme.of(context), isCancel), onPressed: onPressed, child: Text(_txt, overflow: TextOverflow.ellipsis, textScaleFactor: MediaQuery.of(context).textScaleFactor, style: textStyle)); } else { return textStyle == null ? widget : DefaultTextStyle(style: textStyle, child: widget); } }

bool _changing = false; bool _wait = true; final Map<int, int> lastData = {};

List _buildViews() { if (picker.printDebug) print("_buildViews"); if (theme == null) theme = Theme.of(context); for (int j = 0; j < _keys.length; j++) _keys[j] = null;

List<Widget> items = [];
PickerAdapter? adapter = picker.adapter;
adapter.setColumn(-1);

final _decoration = BoxDecoration(
  color: picker.containerColor == null
      ? theme!.dialogBackgroundColor
      : picker.containerColor,
);

if (adapter.length > 0) {
  for (int i = 0; i < picker._maxLevel; i++) {
    Widget view = Expanded(
      flex: adapter.getColumnFlex(i),
      child: Container(
        padding: picker.columnPadding,
        height: picker.height,
        decoration: _decoration,
        child: _wait
            ? null
            : StatefulBuilder(
                builder: (context, state) {
                  _keys[i] = state;
                  adapter.setColumn(i - 1);
                  if (picker.printDebug) print("builder. col: $i");

                  // 上一次是空列表
                  final _lastIsEmpty = scrollController[i].hasClients &&
                      !scrollController[i].position.hasContentDimensions;

                  final _length = adapter.length;
                  final _view = _buildCupertinoPicker(context, i, _length,
                      adapter, _lastIsEmpty ? ValueKey(_length) : null);

                  if (_lastIsEmpty ||
                      (!picker.changeToFirst &&
                          picker.selecteds[i] >= _length)) {
                    Timer(Duration(milliseconds: 100), () {
                      if (!this.mounted) return;
                      if (picker.printDebug) print("timer last");
                      var _len = adapter.length;
                      var _index = (_len < _length ? _len : _length) - 1;
                      if (scrollController[i]
                          .position
                          .hasContentDimensions) {
                        scrollController[i].jumpToItem(_index);
                      } else {
                        scrollController[i] = FixedExtentScrollController(
                            initialItem: _index);
                        if (_keys[i] != null) {
                          _keys[i]!(() => null);
                        }
                      }
                    });
                  }

                  return _view;
                },
              ),
      ),
    );
    items.add(view);
  }
}

if (picker.delimiter != null && !_wait) {
  for (int i = 0; i < picker.delimiter!.length; i++) {
    var o = picker.delimiter![i];
    if (o.child == null) continue;
    var item = SizedBox(
        child: DecoratedBox(
          decoration: _decoration,
          child: o.child,
        ),
        height: picker.height);
    if (o.column < 0)
      items.insert(0, item);
    else if (o.column >= items.length)
      items.add(item);
    else
      items.insert(o.column, item);
  }
}

if (picker.reversedOrder) return items.reversed.toList();

return items;

}

Map m = {};

Widget _buildCupertinoPicker(BuildContext context, int i, int _length, PickerAdapter adapter, Key? key) { if(!m.containsKey(i)){ //isMouseWheel:为了维持鼠标拖拽时的丝滑，如果不做这个处理，那么鼠标拖拽时也会每次只能跳一格 m[i] = {"isMouseWheel":false,"indexCorrect":scrollController[i].initialItem,}; } return Listener( onPointerSignal: (PointerSignalEvent event) { if (event is PointerScrollEvent) { m[i]["isMouseWheel"] = true; } }, child: CupertinoPicker.builder( key: key, backgroundColor: picker.backgroundColor, scrollController: scrollController[i], itemExtent: picker.itemExtent, // looping: picker.looping, magnification: picker.magnification, diameterRatio: picker.diameterRatio, squeeze: picker.squeeze, selectionOverlay: picker.selectionOverlay, childCount: picker.looping ? null : _length, itemBuilder: (context, index) { adapter.setColumn(i - 1); return adapter.buildItem(context, index % _length); }, onSelectedItemChanged: (int selectedIndex) { if (_length <= 0) return; if(m[i]["isMouseWheel"] == true){ if (selectedIndex > m[i]["indexCorrect"]) { m[i]["indexCorrect"] = m[i]["indexCorrect"] + 1; scrollController[i].jumpToItem(m[i]["indexCorrect"]); } else if (selectedIndex < m[i]["indexCorrect"]) { scrollController[i].jumpToItem(--m[i]["indexCorrect"]); } m[i]["isMouseWheel"] = false; }else{ m[i]["indexCorrect"] = selectedIndex; } var index = m[i]["indexCorrect"] % _length; if (picker.printDebug) print("onSelectedItemChanged. col: $i, row: $index"); picker.selecteds[i] = index; updateScrollController(i); adapter.doSelect(i, index); if (picker.changeToFirst) { for (int j = i + 1; j < picker.selecteds.length; j++) { picker.selecteds[j] = 0; scrollController[j].jumpTo(0.0); } } if (picker.onSelect != null) picker.onSelect!(picker, i, picker.selecteds);

      if (adapter.needUpdatePrev(i)) {
        for (int j = 0; j < picker.selecteds.length; j++) {
          if (j != i && _keys[j] != null) {
            adapter.setColumn(j - 1);
            _keys[j]!(() => null);
          }
        }
        // setState(() {});
      } else {
        if (_keys[i] != null) _keys[i]!(() => null);
        if (adapter.isLinkage) {
          for (int j = i + 1; j < picker.selecteds.length; j++) {
            if (j == i) continue;
            adapter.setColumn(j - 1);
            _keys[j]?.call(() => null);
          }
        }
      }
    },
  ),
);

}

void updateScrollController(int col) { if (_changing || picker.adapter.isLinkage == false) return; _changing = true; for (int j = 0; j < picker.selecteds.length; j++) { if (j != col) { if (scrollController[j].hasClients && scrollController[j].position.hasContentDimensions) { scrollController[j].position.notifyListeners(); } } } _changing = false; }

@override void debugFillProperties(properties) { super.debugFillProperties(properties); properties.add(DiagnosticsProperty('_changing', _changing)); } }

/// 选择器数据适配器 abstract class PickerAdapter { Picker? picker;

int getLength(); int getMaxLevel(); void setColumn(int index); void initSelects(); Widget buildItem(BuildContext context, int index);

/// 是否需要更新前面的列 /// Need to update previous columns bool needUpdatePrev(int curIndex) { return false; }

Widget makeText(Widget? child, String? text, bool isSel) { final theme = picker!.textStyle != null || picker!.state?.context == null ? null : Theme.of(picker!.state!.context); return Center( child: DefaultTextStyle( overflow: TextOverflow.ellipsis, maxLines: 1, textAlign: picker!.textAlign, style: picker!.textStyle ?? TextStyle( color: theme?.brightness == Brightness.dark ? Colors.white : Colors.black87, fontFamily: theme == null ? "" : theme.textTheme.headline6?.fontFamily, fontSize: Picker.DefaultTextSize), child: child != null ? (isSel && picker!.selectedIconTheme != null ? IconTheme( data: picker!.selectedIconTheme!, child: child, ) : child) : Text(text ?? "", textScaleFactor: picker!.textScaleFactor, style: (isSel ? picker!.selectedTextStyle : null)))); }

Widget makeTextEx( Widget? child, String text, Widget? postfix, Widget? suffix, bool isSel) { List items = []; if (postfix != null) items.add(postfix); items.add( child ?? Text(text, style: (isSel ? picker!.selectedTextStyle : null))); if (suffix != null) items.add(suffix); final theme = picker!.textStyle != null || picker!.state?.context == null ? null : Theme.of(picker!.state!.context); Color? _txtColor = theme?.brightness == Brightness.dark ? Colors.white : Colors.black87; double? _txtSize = Picker.DefaultTextSize; if (isSel && picker!.selectedTextStyle != null) { if (picker!.selectedTextStyle!.color != null) _txtColor = picker!.selectedTextStyle!.color; if (picker!.selectedTextStyle!.fontSize != null) _txtSize = picker!.selectedTextStyle!.fontSize; }

return Center(
    child: DefaultTextStyle(
        overflow: TextOverflow.ellipsis,
        maxLines: 1,
        textAlign: picker!.textAlign,
        style: picker!.textStyle ??
            TextStyle(
                color: _txtColor,
                fontSize: _txtSize,
                fontFamily: theme == null
                    ? ""
                    : theme.textTheme.headline6?.fontFamily),
        child: Wrap(
          children: items,
        )));

}

String getText() { return getSelectedValues().toString(); }

List getSelectedValues() { return []; }

void doShow() {} void doSelect(int column, int index) {}

int getColumnFlex(int column) { if (picker!.columnFlex != null && column < picker!.columnFlex!.length) return picker!.columnFlex![column]; return 1; }

int get maxLevel => getMaxLevel();

/// Content length of current column int get length => getLength();

String get text => getText();

// 是否联动，即后面的列受前面列数据影响 bool get isLinkage => getIsLinkage();

@override String toString() { return getText(); }

bool getIsLinkage() { return true; }

/// 通知适配器数据改变 void notifyDataChanged() { if (picker?.state != null) { picker!.adapter.doShow(); picker!.adapter.initSelects(); for (int j = 0; j < picker!.selecteds.length; j++) { picker!.state!.scrollController[j].jumpToItem(picker!.selecteds[j]); } } } }

/// 数据适配器 class PickerDataAdapter extends PickerAdapter { late List<PickerItem> data; List<PickerItem>? _datas; int _maxLevel = -1; int _col = 0; final bool isArray;

PickerDataAdapter( {List? pickerData, List<PickerItem>? data, this.isArray = false}) { this.data = data ?? <PickerItem>[]; _parseData(pickerData); }

@override bool getIsLinkage() { return !isArray; }

void _parseData(List? pickerData) { if (pickerData != null && pickerData.length > 0 && (data.length == 0)) { if (isArray) { _parseArrayPickerDataItem(pickerData, data); } else { _parsePickerDataItem(pickerData, data); } } }

_parseArrayPickerDataItem(List? pickerData, List data) { if (pickerData == null) return; var len = pickerData.length; for (int i = 0; i < len; i++) { var v = pickerData[i]; if (!(v is List)) continue; List lv = v; if (lv.length == 0) continue;

  PickerItem item = PickerItem<T>(children: <PickerItem<T>>[]);
  data.add(item);

  for (int j = 0; j < lv.length; j++) {
    var o = lv[j];
    if (o is T) {
      item.children!.add(PickerItem<T>(value: o));
    } else if (T == String) {
      String _v = o.toString();
      item.children!.add(PickerItem<T>(value: _v as T));
    }
  }
}
if (picker?.printDebug == true) print("data.length: ${data.length}");

}

_parsePickerDataItem(List? pickerData, List data) { if (pickerData == null) return; var len = pickerData.length; for (int i = 0; i < len; i++) { var item = pickerData[i]; if (item is T) { data.add(new PickerItem(value: item)); } else if (item is Map) { final Map map = item; if (map.length == 0) continue;

    List<T> _mapList = map.keys.toList().cast();
    for (int j = 0; j < _mapList.length; j++) {
      var _o = map[_mapList[j]];
      if (_o is List && _o.length > 0) {
        List<PickerItem<T>> _children = <PickerItem<T>>[];
        //print('add: ${data.runtimeType.toString()}');
        data.add(PickerItem<T>(value: _mapList[j], children: _children));
        _parsePickerDataItem(_o, _children);
      }
    }
  } else if (T == String && !(item is List)) {
    String _v = item.toString();
    //print('add: $_v');
    data.add(PickerItem<T>(value: _v as T));
  }
}

}

void setColumn(int index) { if (_datas != null && _col == index + 1) return; _col = index + 1; if (isArray) { if (picker!.printDebug) print("index: $index"); if (_col < data.length) _datas = data[_col].children; else _datas = null; return; } if (index < 0) { _datas = data; } else { _datas = data; // 列数过多会有性能问题 for (int i = 0; i <= index; i++) { var j = picker!.selecteds[i]; if (_datas != null && _datas!.length > j) _datas = _datas![j].children; else { _datas = null; break; } } } }

@override int getLength() => _datas?.length ?? 0;

@override getMaxLevel() { if (_maxLevel == -1) _checkPickerDataLevel(data, 1); return _maxLevel; }

@override Widget buildItem(BuildContext context, int index) { final PickerItem item = _datas![index]; final isSel = index == picker!.selecteds[_col]; if (picker!.onBuilderItem != null) { final _v = picker!.onBuilderItem!( context, item.value.toString(), item.text, isSel, _col, index); if (_v != null) return makeText(_v, null, isSel); } if (item.text != null) { return isSel && picker!.selectedTextStyle != null ? DefaultTextStyle( style: picker!.selectedTextStyle!, textAlign: picker!.textAlign, child: picker!.selectedIconTheme != null ? IconTheme( data: picker!.selectedIconTheme!, child: item.text!, ) : item.text!) : item.text!; } return makeText( item.text, item.text != null ? null : item.value.toString(), isSel); }

@override void initSelects() { // ignore: unnecessary_null_comparison if (picker!.selecteds == null) picker!.selecteds = []; if (picker!.selecteds.length == 0) { for (int i = 0; i < _maxLevel; i++) picker!.selecteds.add(0); } }

@override List getSelectedValues() { List _items = []; var _sLen = picker!.selecteds.length; if (isArray) { for (int i = 0; i < _sLen; i++) { int j = picker!.selecteds[i]; if (j < 0 || data[i].children == null || j >= data[i].children!.length) break; _items.add(data[i].children![j].value!); } } else { List<PickerItem>? datas = data; for (int i = 0; i < _sLen; i++) { int j = picker!.selecteds[i]; if (j < 0 || j >= datas!.length) break; _items.add(datas[j].value); datas = datas[j].children; if (datas == null || datas.length == 0) break; } } return _items; }

_checkPickerDataLevel(List? data, int level) { if (data == null) return; if (isArray) { _maxLevel = data.length; return; } for (int i = 0; i < data.length; i++) { if (data[i].children != null && data[i].children!.length > 0) _checkPickerDataLevel(data[i].children, level + 1); } if (_maxLevel < level) _maxLevel = level; } }

class NumberPickerColumn { final List? items; final int begin; final int end; final int? initValue; final int columnFlex; final int jump; final Widget? postfix, suffix; final PickerValueFormat? onFormatValue;

const NumberPickerColumn({ this.begin = 0, this.end = 9, this.items, this.initValue, this.jump = 1, this.columnFlex = 1, this.postfix, this.suffix, this.onFormatValue, });

int indexOf(int? value) { if (value == null) return -1; if (items != null) return items!.indexOf(value); if (value < begin || value > end) return -1; return (value - begin) ~/ (this.jump == 0 ? 1 : this.jump); }

int valueOf(int index) { if (items != null) { return items![index]; } return begin + index * (this.jump == 0 ? 1 : this.jump); }

String getValueText(int index) { return onFormatValue == null ? "${valueOf(index)}" : onFormatValue!(valueOf(index)); }

int count() { var v = (end - begin) ~/ (this.jump == 0 ? 1 : this.jump) + 1; if (v < 1) return 0; return v; } }

class NumberPickerAdapter extends PickerAdapter { NumberPickerAdapter({required this.data});

final List data; NumberPickerColumn? cur; int _col = 0;

@override int getLength() { if (cur == null) return 0; if (cur!.items != null) return cur!.items!.length; return cur!.count(); }

@override int getMaxLevel() => data.length;

@override bool getIsLinkage() { return false; }

@override void setColumn(int index) { if (index != -1 && _col == index + 1) return; _col = index + 1; if (_col >= data.length) { cur = null; } else { cur = data[_col]; } }

@override void initSelects() { int _maxLevel = getMaxLevel(); // ignore: unnecessary_null_comparison if (picker!.selecteds == null) picker!.selecteds = []; if (picker!.selecteds.length == 0) { for (int i = 0; i < _maxLevel; i++) { int v = data[i].indexOf(data[i].initValue); if (v < 0) v = 0; picker!.selecteds.add(v); } } }

@override Widget buildItem(BuildContext context, int index) { final txt = cur!.getValueText(index); final isSel = index == picker!.selecteds[_col]; if (picker!.onBuilderItem != null) { final _v = picker!.onBuilderItem!(context, txt, null, isSel, _col, index); if (_v != null) return makeText(_v, null, isSel); } if (cur!.postfix == null && cur!.suffix == null) return makeText(null, txt, isSel); else return makeTextEx(null, txt, cur!.postfix, cur!.suffix, isSel); }

@override int getColumnFlex(int column) { return data[column].columnFlex; }

@override List getSelectedValues() { List _items = []; for (int i = 0; i < picker!.selecteds.length; i++) { int j = picker!.selecteds[i]; int v = data[i].valueOf(j); _items.add(v); } return _items; } }

/// Picker DateTime Adapter Type class PickerDateTimeType { static const int kMDY = 0; // m, d, y static const int kHM = 1; // hh, mm static const int kHMS = 2; // hh, mm, ss static const int kHM_AP = 3; // hh, mm, ap(AM/PM) static const int kMDYHM = 4; // m, d, y, hh, mm static const int kMDYHM_AP = 5; // m, d, y, hh, mm, AM/PM static const int kMDYHMS = 6; // m, d, y, hh, mm, ss

static const int kYMD = 7; // y, m, d static const int kYMDHM = 8; // y, m, d, hh, mm static const int kYMDHMS = 9; // y, m, d, hh, mm, ss static const int kYMD_AP_HM = 10; // y, m, d, ap, hh, mm

static const int kYM = 11; // y, m static const int kDMY = 12; // d, m, y static const int kY = 13; // y }

class DateTimePickerAdapter extends PickerAdapter { /// display type, ref: [columnType] final int type;

/// Whether to display the month in numerical form.If true, months is not used. final bool isNumberMonth;

/// custom months strings final List? months;

/// Custom AM, PM strings final List? strAMPM;

/// year begin...end. final int? yearBegin, yearEnd;

/// hour min ... max, min >= 0, max <= 23, max > min final int? minHour, maxHour;

/// minimum datetime final DateTime? minValue, maxValue;

/// jump minutes, user could select time in intervals of 30min, 5mins, etc.... final int? minuteInterval;

/// Year, month, day suffix final String? yearSuffix, monthSuffix, daySuffix, hourSuffix, minuteSuffix, secondSuffix;

/// use two-digit year, 2019, displayed as 19 final bool twoDigitYear;

/// year 0, month 1, day 2, hour 3, minute 4, sec 5, am/pm 6, hour-ap: 7 final List? customColumnType;

static const List MonthsList_EN = const [ "Jan", "Feb", "Mar", "Apr", "May", "Jun", "Jul", "Aug", "Sep", "Oct", "Nov", "Dec" ];

static const List MonthsList_EN_L = const [ "January", "February", "March", "April", "May", "June", "July", "August", "September", "October", "November", "December" ];

DateTimePickerAdapter({ Picker? picker, this.type = 0, this.isNumberMonth = false, this.months = MonthsList_EN, this.strAMPM, this.yearBegin = 1900, this.yearEnd = 2100, this.value, this.minValue, this.maxValue, this.minHour, this.maxHour, this.secondSuffix, this.minuteSuffix, this.hourSuffix, this.yearSuffix, this.monthSuffix, this.daySuffix, this.minuteInterval, this.customColumnType, this.twoDigitYear = false, }) : assert(minuteInterval == null || (minuteInterval >= 1 && minuteInterval <= 30 && (60 % minuteInterval == 0))) { super.picker = picker; _yearBegin = yearBegin ?? 0; if (minValue != null && minValue!.year > _yearBegin) { _yearBegin = minValue!.year; } // Judge whether the day is in front of the month // If in the front, set "needUpdatePrev" = true List _columnType; if (customColumnType != null) _columnType = customColumnType!; else _columnType = columnType[type]; var month = _columnType.indexWhere((element) => element == 1); var day = _columnType.indexWhere((element) => element == 2); _needUpdatePrev = day < month || day < _columnType.indexWhere((element) => element == 0); if (!_needUpdatePrev) { // check am/pm before hour-ap var ap = _columnType.indexWhere((element) => element == 6); if (ap > _columnType.indexWhere((element) => element == 7)) { _apBeforeHourAp = true; _needUpdatePrev = true; } } if (value == null) { value = DateTime.now(); } _existSec = existSec(); _verificationMinMaxValue(); }

bool _existSec = false; int _col = 0; int _colAP = -1; int _colHour = -1; int _colDay = -1; int _yearBegin = 0; bool _needUpdatePrev = false; bool _apBeforeHourAp = false;

/// Currently selected value DateTime? value;

// but it can improve the performance, so keep it. static const List<List> lengths = const [ [12, 31, 0], [24, 60], [24, 60, 60], [12, 60, 2], [12, 31, 0, 24, 60], [12, 31, 0, 12, 60, 2], [12, 31, 0, 24, 60, 60], [0, 12, 31], [0, 12, 31, 24, 60], [0, 12, 31, 24, 60, 60], [0, 12, 31, 2, 12, 60], [0, 12], [31, 12, 0], [0], ];

static const Map<int, int> columnTypeLength = { 0: 0, 1: 12, 2: 31, 3: 24, 4: 60, 5: 60, 6: 2, 7: 12 };

/// year 0, month 1, day 2, hour 3, minute 4, sec 5, am/pm 6, hour-ap: 7 static const List<List> columnType = const [ [1, 2, 0], [3, 4], [3, 4, 5], [7, 4, 6], [1, 2, 0, 3, 4], [1, 2, 0, 7, 4, 6], [1, 2, 0, 3, 4, 5], [0, 1, 2], [0, 1, 2, 3, 4], [0, 1, 2, 3, 4, 5], [0, 1, 2, 6, 7, 4], [0, 1], [2, 1, 0], [0], ];

// static const List leapYearMonths = const [1, 3, 5, 7, 8, 10, 12];

// 获取当前列的类型 int getColumnType(int index) { if (customColumnType != null) return customColumnType![index]; List items = columnType[type]; if (index >= items.length) return -1; return items[index]; }

// 判断是否存在秒 bool existSec() { final _columns = customColumnType == null ? columnType[type] : customColumnType!; return _columns.indexOf(5) >= 0; }

@override int getLength() { int v = (customColumnType == null ? lengths[type][_col] : columnTypeLength[customColumnType![_col]])!; if (v == 0) { int ye = yearEnd!; if (maxValue != null) ye = maxValue!.year; return ye - _yearBegin + 1; } if (v == 31) return _calcDateCount(value!.year, value!.month); int _type = getColumnType(_col); switch (_type) { case 3: // hour if ((minHour != null && minHour! >= 0) || (maxHour != null && maxHour! <= 23)) return (maxHour ?? 23) - (minHour ?? 0) + 1; break; case 4: // minute if (minuteInterval != null && minuteInterval! > 1) return v ~/ minuteInterval!; break; case 7: // hour am/pm if ((minHour != null && minHour! >= 0) || (maxHour != null && maxHour! <= 23)) if (_colAP < 0) { // I don't know AM or PM return 12; } else { var _min = 0; var _max = 0; if (picker!.selecteds[_colAP] == 0) { // am _min = minHour == null ? 1 : minHour! >= 12 ? 12 : minHour! + 1; _max = maxHour == null ? 12 : maxHour! >= 12 ? 12 : maxHour! + 1; } else { // pm _min = minHour == null ? 1 : minHour! >= 12 ? 24 - minHour! - 12 : 1; _max = maxHour == null ? 12 : maxHour! >= 12 ? maxHour! - 12 : 1; } return _max > _min ? _max - _min + 1 : _min - _max + 1; } break; } return v; }

@override int getMaxLevel() { return customColumnType == null ? lengths[type].length : customColumnType!.length; }

@override bool needUpdatePrev(int curIndex) { if (_needUpdatePrev) { if (value?.month == 2) { // Only February needs to be dealt with var _curType = getColumnType(curIndex); return _curType == 1 || _curType == 0; } else if (_apBeforeHourAp) { return getColumnType(curIndex) == 6; } } return false; }

@override void setColumn(int index) { //print("setColumn index: $index"); _col = index + 1; if (_col < 0) _col = 0; }

@override void initSelects() { _colAP = _getAPColIndex(); int _maxLevel = getMaxLevel(); // ignore: unnecessary_null_comparison if (picker!.selecteds == null) picker!.selecteds = []; if (picker!.selecteds.length == 0) { for (int i = 0; i < _maxLevel; i++) picker!.selecteds.add(0); } }

@override Widget buildItem(BuildContext context, int index) { String _text = ""; int colType = getColumnType(_col); switch (colType) { case 0: if (twoDigitYear) { _text = "${_yearBegin + index}"; var _l = _text.length; _text = "${_text.substring(_l - (_l - 2), _l)}${_checkStr(yearSuffix)}"; } else _text = "${_yearBegin + index}${_checkStr(yearSuffix)}"; break; case 1: if (isNumberMonth) { _text = "${index + 1}${_checkStr(monthSuffix)}"; } else { if (months != null) _text = "${months![index]}"; else { List _months = PickerLocalizations.of(context).months ?? MonthsList_EN; _text = "${_months[index]}"; } } break; case 2: _text = "${index + 1}${_checkStr(daySuffix)}"; break; case 3: _text = "${intToStr(index + (minHour ?? 0))}${_checkStr(hourSuffix)}"; break; case 5: _text = "${intToStr(index)}${_checkStr(secondSuffix)}"; break; case 4: if (minuteInterval == null || minuteInterval! < 2) _text = "${intToStr(index)}${_checkStr(minuteSuffix)}"; else _text = "${intToStr(index * minuteInterval!)}${_checkStr(minuteSuffix)}"; break; case 6: final apStr = strAMPM ?? PickerLocalizations.of(context).ampm ?? const ['AM', 'PM']; _text = "${apStr[index]}"; break; case 7: _text = "${intToStr(index + (minHour == null ? 0 : (picker!.selecteds[_colAP] == 0 ? minHour! : 0)) + 1)}"; break; }

final isSel = picker!.selecteds[_col] == index;
if (picker!.onBuilderItem != null) {
  var _v = picker!.onBuilderItem!(context, _text, null, isSel, _col, index);
  if (_v != null) return makeText(_v, null, isSel);
}
return makeText(null, _text, isSel);

}

@override String getText() { return value.toString(); }

@override int getColumnFlex(int column) { if (picker!.columnFlex != null && column < picker!.columnFlex!.length) return picker!.columnFlex![column]; if (getColumnType(column) == 0) return 3; return 2; }

@override void doShow() { if (_yearBegin == 0) getLength(); var _maxLevel = getMaxLevel(); final sh = value!.hour; for (int i = 0; i < _maxLevel; i++) { int colType = getColumnType(i); switch (colType) { case 0: picker!.selecteds[i] = yearEnd != null && value!.year > yearEnd! ? yearEnd! - _yearBegin : value!.year - _yearBegin; break; case 1: picker!.selecteds[i] = value!.month - 1; break; case 2: picker!.selecteds[i] = value!.day - 1; break; case 3: var h = sh; if ((minHour != null && minHour! >= 0) || (maxHour != null && maxHour! <= 23)) { if (minHour != null) { h = h > minHour! ? h - minHour! : 0; } else { h = (maxHour ?? 23) - (minHour ?? 0) + 1; } } picker!.selecteds[i] = h; break; case 4: // minute if (minuteInterval == null || minuteInterval! < 2) { picker!.selecteds[i] = value!.minute; } else { picker!.selecteds[i] = value!.minute ~/ minuteInterval!; final m = picker!.selecteds[i] * minuteInterval!; if (m != value!.minute) { // 需要更新 value var s = value!.second; if (type != 2 && type != 6) s = 0; final h = _colAP >= 0 ? _calcHourOfAMPM(sh, m) : sh; value = DateTime(value!.year, value!.month, value!.day, h, m, s); } } break; case 5: picker!.selecteds[i] = value!.second; break; case 6: // am/pm picker!.selecteds[i] = (sh > 12 || (sh == 12 && (value!.minute > 0 || value!.second > 0))) ? 1 : 0; break; case 7: picker!.selecteds[i] = sh == 0 ? 11 : (sh > 12) ? sh - 12 - 1 : sh - 1; break; } } }

@override void doSelect(int column, int index) { int year, month, day, h, m, s; year = value!.year; month = value!.month; day = value!.day; h = value!.hour; m = value!.minute; s = _existSec ? value!.second : 0;

int colType = getColumnType(column);
switch (colType) {
  case 0:
    year = _yearBegin + index;
    break;
  case 1:
    month = index + 1;
    break;
  case 2:
    day = index + 1;
    break;
  case 3:
    h = index + (minHour ?? 0);
    break;
  case 4:
    m = (minuteInterval == null || minuteInterval! < 2)
        ? index
        : index * minuteInterval!;
    if (_colAP >= 0) {
      h = _calcHourOfAMPM(h, m);
    }
    break;
  case 5:
    s = index;
    break;
  case 6:
    h = _calcHourOfAMPM(h, m);
    if (minHour != null || maxHour != null) {
      if (minHour != null && _colHour >= 0) {
        if (h < minHour!) {
          picker!.selecteds[_colHour] = 0;
          picker!.updateColumn(_colHour);
          return;
        }
      }
      if (maxHour != null && h > maxHour!) h = maxHour!;
    }
    break;
  case 7:
    h = index +
        (minHour == null
            ? 0
            : (picker!.selecteds[_colAP] == 0 ? minHour! : 0)) +
        1;
    if (_colAP >= 0) {
      h = _calcHourOfAMPM(h, m);
    }
    if (h > 23) h = 0;
    break;
}
int __day = _calcDateCount(year, month);

bool _isChangeDay = false;
if (day > __day) {
  day = __day;
  _isChangeDay = true;
}
value = DateTime(year, month, day, h, m, s);

if (_verificationMinMaxValue()) {
  notifyDataChanged();
} else if (_isChangeDay && _colDay >= 0) {
  doShow();
  picker!.updateColumn(_colDay);
}

}

bool _verificationMinMaxValue() { DateTime? _minV = minValue; DateTime? _maxV = maxValue; if (_minV == null && yearBegin != null) { _minV = DateTime(yearBegin!, 1, 1, minHour ?? 0); } if (_maxV == null && yearEnd != null) { _maxV = DateTime(yearEnd!, 12, 31, maxHour ?? 23, 59, 59); } if (_minV != null && (value!.millisecondsSinceEpoch < _minV.millisecondsSinceEpoch)) { value = _minV; return true; } else if (_maxV != null && value!.millisecondsSinceEpoch > _maxV.millisecondsSinceEpoch) { value = _maxV; return true; } return false; }

// Calculate am/pm time transfer int _calcHourOfAMPM(int h, int m) { // 12:00 AM , 00:00:000 // 12:30 AM , 12:30:000 // 12:00 PM , 12:00:000 // 12:30 PM , 00:30:000 if (picker!.selecteds[_colAP] == 0) { // am if (h == 12 && m == 0) { h = 0; } else if (h == 0 && m > 0) { h = 12; } if (h > 12) h = h - 12; } else { // pm if (h > 0 && h < 12) h = h + 12; if (h == 12 && m > 0) { h = 0; } else if (h == 0 && m == 0) { h = 12; } } return h; }

int _getAPColIndex() { List items = customColumnType ?? columnType[type]; _colHour = items.indexWhere((e) => e == 7); _colDay = items.indexWhere((e) => e == 2); for (int i = 0; i < items.length; i++) { if (items[i] == 6) return i; } return -1; }

int _calcDateCount(int year, int month) { switch (month) { case 1: case 3: case 5: case 7: case 8: case 10: case 12: return 31; case 2: { if ((year % 4 == 0 && year % 100 != 0) || year % 400 == 0) { return 29; } return 28; } } return 30; }

String intToStr(int v) { return (v < 10) ? "0$v" : "$v"; }

String _checkStr(String? v) { return v == null ? "" : v; } }

yangyxd / flutter_picker

Mouse wheel scrolling on Windows not precise #194