[Gallery] Fix directory structure (#312)

gallery/lib/demos/material/tabs_demo.dart

@@ -0,0 +1,118 @@
+// 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 TabsDemoType {
+  scrollable,
+  nonScrollable,
+}
+
+class TabsDemo extends StatelessWidget {
+  const TabsDemo({Key key, this.type}) : super(key: key);
+
+  final TabsDemoType type;
+
+  @override
+  Widget build(BuildContext context) {
+    Widget tabs;
+    switch (type) {
+      case TabsDemoType.scrollable:
+        tabs = _TabsScrollableDemo();
+        break;
+      case TabsDemoType.nonScrollable:
+        tabs = _TabsNonScrollableDemo();
+    }
+    return tabs;
+  }
+}
+
+// BEGIN tabsScrollableDemo
+
+class _TabsScrollableDemo extends StatelessWidget {
+  @override
+  Widget build(BuildContext context) {
+    List<String> tabs = [
+      GalleryLocalizations.of(context).colorsRed,
+      GalleryLocalizations.of(context).colorsOrange,
+      GalleryLocalizations.of(context).colorsGreen,
+      GalleryLocalizations.of(context).colorsBlue,
+      GalleryLocalizations.of(context).colorsIndigo,
+      GalleryLocalizations.of(context).colorsPurple,
+      GalleryLocalizations.of(context).colorsRed,
+      GalleryLocalizations.of(context).colorsOrange,
+      GalleryLocalizations.of(context).colorsGreen,
+      GalleryLocalizations.of(context).colorsBlue,
+      GalleryLocalizations.of(context).colorsIndigo,
+      GalleryLocalizations.of(context).colorsPurple,
+    ];
+
+    return DefaultTabController(
+      length: tabs.length,
+      child: Scaffold(
+        appBar: AppBar(
+          automaticallyImplyLeading: false,
+          title: Text(GalleryLocalizations.of(context).demoTabsScrollingTitle),
+          bottom: TabBar(
+            isScrollable: true,
+            tabs: [
+              for (final tab in tabs) Tab(text: tab),
+            ],
+          ),
+        ),
+        body: TabBarView(
+          children: [
+            for (final tab in tabs)
+              Center(
+                child: Text(tab),
+              ),
+          ],
+        ),
+      ),
+    );
+  }
+}
+
+// END
+
+// BEGIN tabsNonScrollableDemo
+
+class _TabsNonScrollableDemo extends StatelessWidget {
+  @override
+  Widget build(BuildContext context) {
+    List<String> tabs = [
+      GalleryLocalizations.of(context).colorsRed,
+      GalleryLocalizations.of(context).colorsOrange,
+      GalleryLocalizations.of(context).colorsGreen,
+    ];
+
+    return DefaultTabController(
+      length: tabs.length,
+      child: Scaffold(
+        appBar: AppBar(
+          automaticallyImplyLeading: false,
+          title:
+              Text(GalleryLocalizations.of(context).demoTabsNonScrollingTitle),
+          bottom: TabBar(
+            isScrollable: false,
+            tabs: [
+              for (final tab in tabs) Tab(text: tab),
+            ],
+          ),
+        ),
+        body: TabBarView(
+          children: [
+            for (final tab in tabs)
+              Center(
+                child: Text(tab),
+              ),
+          ],
+        ),
+      ),
+    );
+  }
+}
+
+// END