migrate picker to null safety (#91)

* Theme: 优化单例实现，初步优化 BrnAllThemeConfig 属性获取不为 null

* refactor:优化theme,暴露非null引用

* theme:去除无用信息及优化部分代码

* theme:增加属性类型

* 优化修复 EventBus

* 迁移example ，优化常量命名，增加export

* migrate brn_empty_status.dart

* 删除 BrnThemeImg

* fix:tagConfig merge方法增加判空处理

* fix:revert tagConfig

* fix:BrnAbnormalStateWidget空处理

* Migrated tabbar to null-safety

* Migrated scroll_anchor to null-safety

* fix:修复迁移tabar问题

* migrate form to null safety

* fix：修复tabbar报错及selection警告信息

* fix:修复迁移问题

* fix:优化迁移部分问题key和style非空问题

* migrate picker to null safety

* fix:修复picker空安全迁移问题

* fix:修复list没指定泛型及if判断错误问题

* fix:migrate dashed line to null safty

example/lib/sample/components/line/dashed_line_example.dart

@@ -35,7 +35,7 @@ class _DashedLineExampleState extends State<DashedLineExample> {
               axis: Axis.vertical,
               color: Colors.red,
               dashedOffset: 20,
-              position: BrnDashedLinePosition.DashedLineLeading,
+              position: BrnDashedLinePosition.leading,
               contentWidget: Container(
                 margin: EdgeInsets.only(left: 60, right: 20, top: 10, bottom: 10),
                 child:
@@ -56,7 +56,7 @@ class _DashedLineExampleState extends State<DashedLineExample> {
               axis: Axis.horizontal,
               color: Colors.green,
               dashedOffset: 20,
-              position: BrnDashedLinePosition.DashedLineLeading,
+              position: BrnDashedLinePosition.leading,
               contentWidget: Container(
                 width: 200,
                 height: 100,

example/lib/sample/components/picker/date_picker_example.dart

@@ -156,7 +156,7 @@ class DatePickerExamplePage extends StatelessWidget {
     format = 'HH时:mm分';
     BrnPickerTitleConfig timePickerTheme = BrnPickerTitleConfig(
         title: BrnPickerTitleConfig.Default.title,
-        showTitle: PICKER_SHOW_TITLE_DEFAULT,
+        showTitle: pickerShowTitleDefault,
         titleContent: "选择时间范围");
     BrnDateRangePicker.showDatePicker(context,
         minDateTime: DateTime.parse(MIN_DATETIME),

example/lib/sample/components/picker/picker_entry_page.dart

@@ -82,7 +82,7 @@ class PickerEntryPage extends StatelessWidget {
               describe: "底部级联选择框",
               onPressed: () {
                 rootBundle.loadString('assets/list_picker.json').then((data) {
-                  List<BrnPickerEntity> _selectionData = List()
+                  List<BrnPickerEntity> _selectionData = []
                     ..addAll((JsonDecoder().convert(data)["data"]['list'] as List ?? [])
                         .map((o) => BrnPickerEntity.fromMap(o)));
                   if (_selectionData != null && _selectionData.length > 0) {
@@ -100,7 +100,7 @@ class PickerEntryPage extends StatelessWidget {
               describe: "底部级联选择框（Title 动态改变）",
               onPressed: () {
                 rootBundle.loadString('assets/list_picker.json').then((data) {
-                  List<BrnPickerEntity> _selectionData = List()
+                  List<BrnPickerEntity> _selectionData = []
                     ..addAll((JsonDecoder().convert(data)["data"]['list'] as List ?? [])
                         .map((o) => BrnPickerEntity.fromMap(o)));
                   if (_selectionData != null && _selectionData.length > 0) {
@@ -131,7 +131,7 @@ class PickerEntryPage extends StatelessWidget {
 
   ///多选弹框
   void _showBottomMultiSelectPicker(BuildContext context) {
-    List<BrnMultiSelectBottomPickerItem> items = new List();
+    List<BrnMultiSelectBottomPickerItem> items = [];
     items.add(new BrnMultiSelectBottomPickerItem("100", "这里是标题1"));
     items.add(new BrnMultiSelectBottomPickerItem("101", "这里是标题2"));
     items.add(new BrnMultiSelectBottomPickerItem("102", "这里是标题3", isChecked: true));
@@ -353,7 +353,7 @@ class PickerEntryPage extends StatelessWidget {
     List<BrnTagInputItemBean> items = List();
     for (int i = 0; i < tags.length; i++) {
       String it = tags[i];
-      BrnTagInputItemBean item = BrnTagInputItemBean(name: it, index: i, needExplane: (i % 2 == 0));
+      BrnTagInputItemBean item = BrnTagInputItemBean(name: it, index: i, needExpend: (i % 2 == 0));
       items.add(item);
     }
 
@@ -371,8 +371,8 @@ class PickerEntryPage extends StatelessWidget {
                 tagItemSource: items,
                 tagTitleFontSize: 12,
                 tagTitleColor: Color(0xff222222),
-                tagBackgroudColor: Color(0xffF8F8F8),
-                selectedTagBackgroudColor: Color(0x140984F9),
+                tagBackgroundColor: Color(0xffF8F8F8),
+                selectedTagBackgroundColor: Color(0x140984F9),
                 selectedTagTitleColor: Color(0xFF0984F9),
               ),
               onTagValueGetter: (choice) {

lib/src/components/line/brn_dashed_line.dart

@@ -1,5 +1,3 @@
-// @dart=2.9
-
 import 'package:bruno/src/theme/brn_theme_configurator.dart';
 import 'package:flutter/material.dart';
 
@@ -13,33 +11,29 @@ import 'package:flutter/material.dart';
 /// 分割线所在位置
 enum BrnDashedLinePosition {
   /// 头部
-  DashedLineTrailing,
+  trailing,
 
   /// 尾部
-  DashedLineLeading,
+  leading,
 }
 
-/// 虚线分割线
-class BrnDashedLine extends StatelessWidget {
-  /// 默认虚线方向
-  static const Axis _normalAxis = Axis.horizontal;
+/// 默认虚线方向
+const Axis _normalAxis = Axis.horizontal;
 
-  /// 默认虚线长度
-  static const double _normalDashedLength = 8;
+/// 默认虚线长度
+const double _normalDashedLength = 8;
 
-  /// 默认虚线厚度
-  static const double _normalDashedThickness = 1;
+/// 默认虚线厚度
+const double _normalDashedThickness = 1;
 
-  /// 默认间距
-  static const double _normalDashedSpacing = 4;
+/// 默认间距
+const double _normalDashedSpacing = 4;
 
-  /// 默认颜色
-  static Color _normalColor =
-      BrnThemeConfigurator.instance.getConfig().commonConfig.dividerColorBase;
+/// 默认位置，头部
+const BrnDashedLinePosition _normalPosition = BrnDashedLinePosition.leading;
 
-  /// 默认位置，头部
-  static const BrnDashedLinePosition _normalPosition =
-      BrnDashedLinePosition.DashedLineLeading;
+/// 虚线分割线
+class BrnDashedLine extends StatelessWidget {
 
   /// 虚线方向，默认值[_normalAxis]
   final Axis axis;
@@ -54,7 +48,7 @@ class BrnDashedLine extends StatelessWidget {
   final double dashedSpacing;
 
   /// 颜色，默认值[_normalColor]
-  final Color color;
+  final Color? color;
 
   /// 虚线的Widget
   final Widget contentWidget;
@@ -66,28 +60,28 @@ class BrnDashedLine extends StatelessWidget {
   final BrnDashedLinePosition position;
 
   BrnDashedLine({
-    Key key,
-    @required this.contentWidget,
-    this.axis,
-    this.dashedLength,
-    this.dashedThickness,
-    this.dashedSpacing,
+    Key? key,
+    required this.contentWidget,
+    this.axis = _normalAxis,
+    this.dashedLength = _normalDashedLength,
+    this.dashedThickness = _normalDashedThickness,
+    this.dashedSpacing = _normalDashedSpacing,
     this.color,
-    this.dashedOffset,
-    this.position,
+    this.dashedOffset = 0.0,
+    this.position = _normalPosition,
   });
 
   @override
   Widget build(BuildContext context) {
     return CustomPaint(
       painter: BrnDashedPainter(
-          axis: this.axis ?? _normalAxis,
-          dashedLength: this.dashedLength ?? _normalDashedLength,
-          dashedThickness: this.dashedThickness ?? _normalDashedThickness,
-          dashedSpacing: this.dashedSpacing ?? _normalDashedSpacing,
-          color: this.color ?? _normalColor,
-          dashedOffset: this.dashedOffset ?? 0,
-          position: this.position ?? _normalPosition),
+          axis: this.axis,
+          dashedLength: this.dashedLength ,
+          dashedThickness: this.dashedThickness,
+          dashedSpacing: this.dashedSpacing ,
+          color: this.color ,
+          dashedOffset: this.dashedOffset,
+          position: this.position),
       child: this.contentWidget,
     );
   }
@@ -107,30 +101,30 @@ class BrnDashedPainter extends CustomPainter {
   final double dashedSpacing;
 
   /// 颜色
-  final Color color;
+  final Color? color;
 
   /// 距离边缘的位置
-  final double dashedOffset;
+  final double? dashedOffset;
 
   /// 分割线所在位置
-  final BrnDashedLinePosition position;
+  final BrnDashedLinePosition? position;
 
   BrnDashedPainter({
-    this.axis,
-    this.dashedLength,
-    this.dashedThickness,
-    this.dashedSpacing,
+    this.axis = _normalAxis,
+    this.dashedLength = _normalDashedLength,
+    this.dashedThickness = _normalDashedThickness,
+    this.dashedSpacing = _normalDashedSpacing,
     this.color,
-    this.dashedOffset,
-    this.position,
+    this.dashedOffset = 0.0,
+    this.position = _normalPosition,
   });
 
   @override
   void paint(Canvas canvas, Size size) {
     var paint = Paint() // 创建一个画笔并配置其属性
       ..strokeWidth = this.dashedThickness // 画笔的宽度
       ..isAntiAlias = true // 是否抗锯齿
-      ..color = this.color; // 画笔颜色
+      ..color = this.color?? BrnThemeConfigurator.instance.getConfig().commonConfig.dividerColorBase; // 画笔颜色
 
     var maxWidth = size.width; // size获取到宽度
     var maxHeight = size.height; // size获取到宽度
@@ -139,12 +133,12 @@ class BrnDashedPainter extends CustomPainter {
       double startX = 0;
       final space = (this.dashedSpacing + this.dashedLength);
       double height = 0;
-      if (this.position == BrnDashedLinePosition.DashedLineLeading) {
+      if (this.position == BrnDashedLinePosition.leading) {
         // 头部
-        height = dashedOffset + this.dashedThickness / 2;
+        height = dashedOffset! + this.dashedThickness / 2;
       } else {
         // 尾部
-        height = size.height - dashedOffset - this.dashedThickness / 2;
+        height = size.height - dashedOffset! - this.dashedThickness / 2;
       }
       while (startX < maxWidth) {
         if ((maxWidth - startX) < this.dashedLength) {
@@ -161,12 +155,12 @@ class BrnDashedPainter extends CustomPainter {
       double startY = 0;
       final space = (this.dashedSpacing + this.dashedLength);
       double width = 0;
-      if (this.position == BrnDashedLinePosition.DashedLineLeading) {
+      if (this.position == BrnDashedLinePosition.leading) {
         // 头部
-        width = dashedOffset + this.dashedThickness / 2;
+        width = dashedOffset! + this.dashedThickness / 2;
       } else {
         // 尾部
-        width = size.width - dashedOffset - this.dashedThickness / 2;
+        width = size.width - dashedOffset! - this.dashedThickness / 2;
       }
       while (startY < maxHeight) {
         if ((maxHeight - startY) < this.dashedLength) {