chore: modernize Flutter examples — null safety, latest APIs, Kotlin DSL Gradle (#148)

* updates

* Update Gradle wrapper script to fetch latest version online and allow --version override

* chore(analytics_integration): migrate Gradle build scripts to Kotlin DSL

Convert Groovy build files to Kotlin DSL and bump Gradle wrapper.

* chore(animation_example): migrate Gradle build scripts to Kotlin DSL

Convert Groovy build files to Kotlin DSL.

* chore(biometrics): migrate Gradle build scripts to Kotlin DSL

Convert Groovy build files to Kotlin DSL.

* chore(bmi_calculator): test

test body

* chore(bottom_sheet): test

test body

* chore(custom_home_drawer): migrate Gradle build scripts to Kotlin DSL

Convert Groovy build files to Kotlin DSL and bump Gradle wrapper.

* chore(covid19_mobile_app): migrate Gradle build scripts to Kotlin DSL

Convert Groovy build.gradle/settings.gradle to Kotlin DSL and bump Gradle wrapper.

* chore(dropdown_button): migrate Gradle build scripts to Kotlin DSL

Convert Groovy build.gradle/settings.gradle to Kotlin DSL and bump Gradle wrapper.

* chore(enabling_splash_screen): migrate Gradle build scripts to Kotlin DSL

Convert Groovy build.gradle/settings.gradle to Kotlin DSL and bump Gradle wrapper.

* chore(expense_planner): migrate Gradle build scripts to Kotlin DSL

Convert Groovy build.gradle/settings.gradle to Kotlin DSL and bump Gradle wrapper.

* chore(firebase_crash_reporting): migrate Gradle build scripts to Kotlin DSL

Convert Groovy build.gradle/settings.gradle to Kotlin DSL and bump Gradle wrapper.

* chore(firebase_google_authentication): migrate Gradle build scripts to Kotlin DSL

Convert Groovy build.gradle/settings.gradle to Kotlin DSL and bump Gradle wrapper.

* chore(flutter_date_pickers-master): migrate Gradle build scripts to Kotlin DSL

Convert Groovy build.gradle/settings.gradle to Kotlin DSL and bump Gradle wrapper.

* chore(getx_counter_app): migrate Gradle build scripts to Kotlin DSL

Convert Groovy build.gradle/settings.gradle to Kotlin DSL and bump Gradle wrapper.

* chore(google_signin): migrate Gradle build scripts to Kotlin DSL

Convert Groovy build.gradle/settings.gradle to Kotlin DSL and bump Gradle wrapper.

* chore(grid_layout): remove legacy nested android project

Delete the redundant nested android/ project directory from the old layout. Also update pubspec.yaml SDK constraints and dependencies.

* chore(handling_routes): migrate Gradle build scripts to Kotlin DSL

Convert Groovy build.gradle/settings.gradle to Kotlin DSL and bump Gradle wrapper.

* chore(image_editor): migrate Gradle build scripts to Kotlin DSL

Convert Groovy build.gradle/settings.gradle to Kotlin DSL and bump Gradle wrapper.

* chore(image_from_network): migrate Gradle build scripts to Kotlin DSL

Convert Groovy build.gradle/settings.gradle to Kotlin DSL and bump Gradle wrapper.

* chore(infinite_list): migrate Gradle build scripts to Kotlin DSL

Convert Groovy build.gradle/settings.gradle to Kotlin DSL and bump Gradle wrapper.

* chore(load_local_image): remove legacy nested android project

Delete the redundant nested android/ project directory from the old layout. Also update pubspec.yaml SDK constraints and dependencies.

* chore(load_local_json): remove legacy nested android project

Delete the redundant nested android/ project directory from the old layout. Also update pubspec.yaml SDK constraints and dependencies.

* chore(lunch_app): migrate Gradle build scripts to Kotlin DSL

Convert Groovy build.gradle/settings.gradle to Kotlin DSL and bump Gradle wrapper.

* chore(navigation_drawer): remove legacy nested android project

Delete the redundant nested android/ project directory from the old layout. Also update pubspec.yaml SDK constraints and dependencies.

* chore(news_memes_app): migrate Gradle build scripts to Kotlin DSL

Convert Groovy build.gradle/settings.gradle to Kotlin DSL and bump Gradle wrapper.

* chore(persist_key_value): remove legacy nested android project

Delete the redundant nested android/ project directory from the old layout. Also update pubspec.yaml SDK constraints and dependencies.

* chore(push_notifications): migrate Gradle build scripts to Kotlin DSL

Convert Groovy build.gradle/settings.gradle to Kotlin DSL and bump Gradle wrapper.

* chore(save_data_locally_with_sqlite): migrate Gradle build scripts to Kotlin DSL

Convert Groovy build.gradle/settings.gradle to Kotlin DSL and bump Gradle wrapper.

* chore(scan_qr_code): migrate Gradle build scripts to Kotlin DSL

Convert Groovy build.gradle/settings.gradle to Kotlin DSL and bump Gradle wrapper.

* chore(simple_material_app): remove legacy nested android project

Delete the redundant nested android/ project directory from the old layout. Also update pubspec.yaml SDK constraints and dependencies.

* chore(sliver_app_bar_example): migrate Gradle build scripts to Kotlin DSL

Convert Groovy build.gradle/settings.gradle to Kotlin DSL and bump Gradle wrapper.

* chore(stateful_widget): remove legacy nested android project

Delete the redundant nested android/ project directory from the old layout. Also update pubspec.yaml SDK constraints and dependencies.

* chore(stateless_widgets): remove legacy nested android project

Delete the redundant nested android/ project directory from the old layout. Also update pubspec.yaml SDK constraints and dependencies.

* chore(statless_counter_app): migrate Gradle build scripts to Kotlin DSL

Convert Groovy build.gradle/settings.gradle to Kotlin DSL and bump Gradle wrapper.

* chore(tic_tac_toe): migrate Gradle build scripts to Kotlin DSL

Convert Groovy build.gradle/settings.gradle to Kotlin DSL and bump Gradle wrapper.

* chore(tip_calculator): remove legacy nested android project

Delete the redundant nested android/ project directory from the old layout. Also update pubspec.yaml SDK constraints and dependencies.

* chore(todo_list_using_provider): migrate Gradle build scripts to Kotlin DSL

Convert Groovy build.gradle/settings.gradle to Kotlin DSL and bump Gradle wrapper.

* chore(unit_testing): migrate Gradle build scripts to Kotlin DSL

Convert Groovy build.gradle/settings.gradle to Kotlin DSL and bump Gradle wrapper.

* chore(using_alert_dialog): remove legacy nested android project

Delete the redundant nested android/ project directory from the old layout. Also update pubspec.yaml SDK constraints and dependencies.

* chore(using_bottom_nav_bar): remove legacy nested android project

Delete the redundant nested android/ project directory from the old layout. Also update pubspec.yaml SDK constraints and dependencies.

* chore(using_custom_fonts): remove legacy nested android project

Delete the redundant nested android/ project directory from the old layout. Also update pubspec.yaml SDK constraints and dependencies.

* chore(using_edittext): remove legacy nested android project

Delete the redundant nested android/ project directory from the old layout. Also update pubspec.yaml SDK constraints and dependencies.

* chore(using_expansionpanel): migrate Gradle build scripts to Kotlin DSL

Convert Groovy build.gradle/settings.gradle to Kotlin DSL and bump Gradle wrapper.

* chore(using_firebase_db): migrate Gradle build scripts to Kotlin DSL

Convert Groovy build.gradle/settings.gradle to Kotlin DSL and bump Gradle wrapper.

* chore(using_gradient): remove legacy nested android project

Delete the redundant nested android/ project directory from the old layout. Also update pubspec.yaml SDK constraints and dependencies.

* chore(using_http_get): remove legacy nested android project

Delete the redundant nested android/ project directory from the old layout. Also update pubspec.yaml SDK constraints and dependencies.

* chore(using_interactiveviewer): migrate Gradle build scripts to Kotlin DSL

Convert Groovy build.gradle/settings.gradle to Kotlin DSL and bump Gradle wrapper.

* chore(using_listview): remove legacy nested android project

Delete the redundant nested android/ project directory from the old layout. Also update pubspec.yaml SDK constraints and dependencies.

* chore(using_listwheelscrollview): migrate Gradle build scripts to Kotlin DSL

Convert Groovy build.gradle/settings.gradle to Kotlin DSL and bump Gradle wrapper.

* chore(using_platform_adaptive): migrate Gradle build scripts to Kotlin DSL

Convert Groovy build.gradle/settings.gradle to Kotlin DSL and bump Gradle wrapper.

* chore(using_snackbar): remove legacy nested android project

Delete the redundant nested android/ project directory from the old layout. Also update pubspec.yaml SDK constraints and dependencies.

* chore(using_stepper): remove legacy nested android project

Delete the redundant nested android/ project directory from the old layout. Also update pubspec.yaml SDK constraints and dependencies.

* chore(using_tabs): remove legacy nested android project

Delete the redundant nested android/ project directory from the old layout. Also update pubspec.yaml SDK constraints and dependencies.

* chore(using_theme): remove legacy nested android project

Delete the redundant nested android/ project directory from the old layout. Also update pubspec.yaml SDK constraints and dependencies.

* chore(view_pdf_file): migrate Gradle build scripts to Kotlin DSL

Convert Groovy build.gradle/settings.gradle to Kotlin DSL and bump Gradle wrapper.

* chore: ignore .trash directory

* chore: remove IDE configs and PR template

* chore(infinite_list): remove legacy nested android project

* refactor(infinite_list): migrate theme to ColorScheme API

* refactor(using_theme): migrate to ColorScheme API

* refactor(analytics_integration): migrate Firebase Analytics API

* refactor(firebase_google_authentication): migrate Google Sign-In API

* refactor(covid19_mobile_app): migrate theme and buttons to current API

* refactor(covid19_mobile_app): replace bezier_chart with fl_chart

* refactor(image_editor): migrate image plugins and button styles

* refactor(scan_qr_code): migrate mobile_scanner API

* refactor(lunch_app): migrate to null safety

* refactor(todo_list_using_provider): migrate to null safety

* refactor(unit_testing): migrate to null safety

* refactor(using_firebase_db): migrate Firebase Database API

* fix(update_gradle_wrapper): edit gradle-wrapper.properties directly

* refactor(push_notifications): migrate Firebase Messaging API

* refactor(using_http_get): migrate to null safety

* refactor(using_listview): migrate to null safety

* refactor(using_listwheelscrollview): migrate to null safety

* refactor(view_pdf_file): migrate to null safety

* refactor(bottom_sheet): migrate to null safety

* refactor(stateless_widgets): migrate to null safety

* chore: regenerate Gradle wrapper

* refactor: move maintenance scripts to Makefile

* chore: remove generated and IDE files

* fix: migrate image_editor to current plugins

* fix: migrate news_memes_app share to share_plus

* fix: migrate view_pdf_file to syncfusion pdf viewer

* fix: update deprecated APIs

* style: remove commented-out code

covid19_mobile_app/lib/widgets/foldable_cell_widgets.dart

@@ -123,18 +123,20 @@ Widget buildInnerBottomWidget(String cases) {
               fontSize: 20.0,
             ),
           )),
-          FlatButton(
+          TextButton(
             onPressed: () {
-              SimpleFoldingCellState foldingCellState =
-                  context.findAncestorStateOfType();
+              SimpleFoldingCellState? foldingCellState =
+                  context.findAncestorStateOfType<SimpleFoldingCellState>();
               foldingCellState?.toggleFold();
             },
             child: Text(
               "Close",
             ),
-            color: Colors.black,
-            shape: StadiumBorder(),
-            splashColor: Colors.white.withOpacity(0.5),
+            style: TextButton.styleFrom(
+              foregroundColor: Colors.black,
+              shape: StadiumBorder(),
+              overlayColor: Colors.white.withOpacity(0.5),
+            ),
           ),
         ],
       ),

covid19_mobile_app/lib/widgets/graph.dart

@@ -1,22 +1,14 @@
 import 'package:flutter/material.dart';
-import 'package:bezier_chart/bezier_chart.dart';
+import 'package:fl_chart/fl_chart.dart';
 
 // Widget that will build the graph
 Widget buildGraph(
     BuildContext context, List<Map<String, dynamic>> datesAndValues) {
-  // Data is avalaible from a particular date and we are getting that here
-  final fromDate = datesAndValues[0]['date'];
-
-  // Data is avalaible until a particular date and we are getting that here
-  final toDate = datesAndValues.last['date'];
-
-  // Add dates and values corresponding to those dates
-  // in a list
-  List<DataPoint<DateTime>> dataPoints = [];
-  for (final dateAndValue in datesAndValues) {
-    dataPoints.add(DataPoint<DateTime>(
-        value: double.parse(dateAndValue['value'].toString()),
-        xAxis: dateAndValue['date']));
+  // Convert the dates and values into chart points.
+  final spots = <FlSpot>[];
+  for (var i = 0; i < datesAndValues.length; i++) {
+    final value = double.parse(datesAndValues[i]['value'].toString());
+    spots.add(FlSpot(i.toDouble(), value));
   }
 
   return Center(
@@ -26,24 +18,22 @@ Widget buildGraph(
       ),
       height: MediaQuery.of(context).size.height / 2,
       width: MediaQuery.of(context).size.width,
-      child: BezierChart(
-        fromDate: fromDate,
-        bezierChartScale: BezierChartScale.WEEKLY,
-        toDate: toDate,
-        selectedDate: toDate,
-        series: [
-          BezierLine(
-            data: dataPoints,
+      child: Padding(
+        padding: const EdgeInsets.all(16.0),
+        child: LineChart(
+          LineChartData(
+            gridData: FlGridData(show: true),
+            titlesData: FlTitlesData(show: true),
+            borderData: FlBorderData(show: true),
+            lineBarsData: [
+              LineChartBarData(
+                spots: spots,
+                isCurved: true,
+                color: Colors.white,
+                belowBarData: BarAreaData(show: false),
+              ),
+            ],
           ),
-        ],
-        config: BezierChartConfig(
-          physics: BouncingScrollPhysics(),
-          verticalIndicatorStrokeWidth: 3.0,
-          verticalIndicatorColor: Colors.black26,
-          showVerticalIndicator: true,
-          verticalIndicatorFixedPosition: false,
-          backgroundColor: Colors.transparent,
-          footerHeight: 30.0,
         ),
       ),
     ),