[Gallery] Fix directory structure (#312)

gallery/lib/demos/material/selection_controls_demo.dart

@@ -0,0 +1,176 @@
+// 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 'package:flutter/material.dart';
+
+import 'package:gallery/l10n/gallery_localizations.dart';
+
+enum SelectionControlsDemoType {
+  checkbox,
+  radio,
+  switches,
+}
+
+class SelectionControlsDemo extends StatelessWidget {
+  SelectionControlsDemo({Key key, @required this.type}) : super(key: key);
+
+  final SelectionControlsDemoType type;
+
+  String _title(BuildContext context) {
+    switch (type) {
+      case SelectionControlsDemoType.checkbox:
+        return GalleryLocalizations.of(context)
+            .demoSelectionControlsCheckboxTitle;
+      case SelectionControlsDemoType.radio:
+        return GalleryLocalizations.of(context).demoSelectionControlsRadioTitle;
+      case SelectionControlsDemoType.switches:
+        return GalleryLocalizations.of(context)
+            .demoSelectionControlsSwitchTitle;
+    }
+    return '';
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    Widget controls;
+    switch (type) {
+      case SelectionControlsDemoType.checkbox:
+        controls = _CheckboxDemo();
+        break;
+      case SelectionControlsDemoType.radio:
+        controls = _RadioDemo();
+        break;
+      case SelectionControlsDemoType.switches:
+        controls = _SwitchDemo();
+        break;
+    }
+
+    return Scaffold(
+      appBar: AppBar(
+        automaticallyImplyLeading: false,
+        title: Text(_title(context)),
+      ),
+      body: controls,
+    );
+  }
+}
+
+// BEGIN selectionControlsDemoCheckbox
+
+class _CheckboxDemo extends StatefulWidget {
+  @override
+  _CheckboxDemoState createState() => _CheckboxDemoState();
+}
+
+class _CheckboxDemoState extends State<_CheckboxDemo> {
+  bool checkboxValueA = true;
+  bool checkboxValueB = false;
+  bool checkboxValueC;
+
+  @override
+  Widget build(BuildContext context) {
+    return Center(
+      child: Row(
+        mainAxisSize: MainAxisSize.min,
+        children: [
+          Checkbox(
+            value: checkboxValueA,
+            onChanged: (value) {
+              setState(() {
+                checkboxValueA = value;
+              });
+            },
+          ),
+          Checkbox(
+            value: checkboxValueB,
+            onChanged: (value) {
+              setState(() {
+                checkboxValueB = value;
+              });
+            },
+          ),
+          Checkbox(
+            value: checkboxValueC,
+            tristate: true,
+            onChanged: (value) {
+              setState(() {
+                checkboxValueC = value;
+              });
+            },
+          ),
+        ],
+      ),
+    );
+  }
+}
+
+// END
+
+// BEGIN selectionControlsDemoRadio
+
+class _RadioDemo extends StatefulWidget {
+  @override
+  _RadioDemoState createState() => _RadioDemoState();
+}
+
+class _RadioDemoState extends State<_RadioDemo> {
+  int radioValue = 0;
+
+  void handleRadioValueChanged(int value) {
+    setState(() {
+      radioValue = value;
+    });
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    return Center(
+      child: Row(
+        mainAxisSize: MainAxisSize.min,
+        children: [
+          for (int index = 0; index < 3; ++index)
+            Radio<int>(
+              value: index,
+              groupValue: radioValue,
+              onChanged: handleRadioValueChanged,
+            ),
+        ],
+      ),
+    );
+  }
+}
+
+// END
+
+// BEGIN selectionControlsDemoSwitches
+
+class _SwitchDemo extends StatefulWidget {
+  @override
+  _SwitchDemoState createState() => _SwitchDemoState();
+}
+
+class _SwitchDemoState extends State<_SwitchDemo> {
+  bool switchValue = false;
+
+  @override
+  Widget build(BuildContext context) {
+    return Center(
+      child: Semantics(
+        container: true,
+        label:
+            GalleryLocalizations.of(context).demoSelectionControlsSwitchTitle,
+        child: Switch(
+          value: switchValue,
+          onChanged: (value) {
+            setState(() {
+              switchValue = value;
+            });
+          },
+        ),
+      ),
+    );
+  }
+}
+
+// END