Mouse wheel scrolling on Windows not precise

[magicmatt007]

Hi,

OS: Windows.
Topic: Select a number form a NumberPickerColumn with the mouse wheel
Problem: Every move of the mouse wheel results in a jump of 3 values. It is not possible to select every value from the picker.
Note: jump is already set to 1. If I set it e.g. to 5, the actual jumps are 5x3 = 15

Any solutions?

Thx

[FragCai]

在PC和web上都有类似的问题。不能准确地控制滚动，而是一次跳几个。

[FragCai]

我采用了一个比较丑的解决方法，在PC上，套上一层GestureDetector，用来支持拖拉，从而精确控制。

[liangtian123]

Me too！Any solutions?I increased the itemExtent parameter and it solved the problem, but when I run it on a large-screen computer, the problem still exists.

[liangtian123]

I solved it，Related to this：flutter/flutter#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;
}
}