[Gallery] Fix directory structure (#312)

gallery/lib/demos/material/picker_demo.dart

@@ -0,0 +1,112 @@
+// Copyright 2019 The Flutter team. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import 'dart:async';
+
+import 'package:flutter/material.dart';
+import 'package:gallery/l10n/gallery_localizations.dart';
+import 'package:intl/intl.dart';
+
+// BEGIN pickerDemo
+
+enum PickerDemoType {
+  date,
+  time,
+}
+
+class PickerDemo extends StatefulWidget {
+  const PickerDemo({Key key, this.type}) : super(key: key);
+
+  final PickerDemoType type;
+
+  @override
+  _PickerDemoState createState() => _PickerDemoState();
+}
+
+class _PickerDemoState extends State<PickerDemo> {
+  DateTime _fromDate = DateTime.now();
+  TimeOfDay _fromTime = TimeOfDay.fromDateTime(DateTime.now());
+
+  String get _title {
+    switch (widget.type) {
+      case PickerDemoType.date:
+        return GalleryLocalizations.of(context).demoDatePickerTitle;
+      case PickerDemoType.time:
+        return GalleryLocalizations.of(context).demoTimePickerTitle;
+    }
+    return '';
+  }
+
+  String get _labelText {
+    switch (widget.type) {
+      case PickerDemoType.date:
+        return DateFormat.yMMMd().format(_fromDate);
+      case PickerDemoType.time:
+        return _fromTime.format(context);
+    }
+    return '';
+  }
+
+  Future<void> _showDatePicker() async {
+    final picked = await showDatePicker(
+      context: context,
+      initialDate: _fromDate,
+      firstDate: DateTime(2015, 1),
+      lastDate: DateTime(2100),
+    );
+    if (picked != null && picked != _fromDate) {
+      setState(() {
+        _fromDate = picked;
+      });
+    }
+  }
+
+  Future<void> _showTimePicker() async {
+    final TimeOfDay picked = await showTimePicker(
+      context: context,
+      initialTime: _fromTime,
+    );
+    if (picked != null && picked != _fromTime) {
+      setState(() {
+        _fromTime = picked;
+      });
+    }
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    return Scaffold(
+      appBar: AppBar(
+        automaticallyImplyLeading: false,
+        title: Text(_title),
+      ),
+      body: Center(
+        child: Column(
+          mainAxisSize: MainAxisSize.min,
+          children: [
+            Text(_labelText),
+            SizedBox(height: 16),
+            RaisedButton(
+              child: Text(
+                GalleryLocalizations.of(context).demoPickersShowPicker,
+              ),
+              onPressed: () {
+                switch (widget.type) {
+                  case PickerDemoType.date:
+                    _showDatePicker();
+                    break;
+                  case PickerDemoType.time:
+                    _showTimePicker();
+                    break;
+                }
+              },
+            )
+          ],
+        ),
+      ),
+    );
+  }
+}
+
+// END