Reordering method and callback in controller. #21

example/pubspec.lock

@@ -142,7 +142,7 @@ packages:
       path: ".."
       relative: true
     source: path
-    version: "1.16.0+1"
+    version: "1.17.0"
   term_glyph:
     dependency: transitive
     description:

lib/src/tabbed_view_controller.dart

@@ -3,6 +3,9 @@ import 'dart:collection';
 import 'package:flutter/widgets.dart';
 import 'package:tabbed_view/src/tab_data.dart';
 
+/// Event that will be triggered when the tab is reorder.
+typedef OnReorder = void Function(int oldIndex, int newIndex);
+
 /// The [TabbedView] controller.
 ///
 /// Stores tabs and selection tab index.
@@ -11,11 +14,11 @@ import 'package:tabbed_view/src/tab_data.dart';
 ///
 /// Remember to dispose of the [TabbedView] when it is no longer needed. This will ensure we discard any resources used by the object.
 class TabbedViewController extends ChangeNotifier {
-  factory TabbedViewController(List<TabData> tabs) {
-    return TabbedViewController._(tabs);
+  factory TabbedViewController(List<TabData> tabs, {OnReorder? onReorder}) {
+    return TabbedViewController._(tabs, onReorder);
   }
 
-  TabbedViewController._(this._tabs) {
+  TabbedViewController._(this._tabs, this.onReorder) {
     if (_tabs.length > 0) {
       _selectedIndex = 0;
     }
@@ -28,6 +31,8 @@ class TabbedViewController extends ChangeNotifier {
 
   int? _selectedIndex;
 
+  final OnReorder? onReorder;
+
   UnmodifiableListView<TabData> get tabs => UnmodifiableListView(_tabs);
 
   /// The selected tab index
@@ -42,6 +47,39 @@ class TabbedViewController extends ChangeNotifier {
     notifyListeners();
   }
 
+  /// Gets the selected tab.
+  TabData? get selectedTab =>
+      _selectedIndex != null ? _tabs[_selectedIndex!] : null;
+
+  /// Reorders a tab.
+  void reorderTab(int oldIndex, int newIndex) {
+    if (_tabs.isEmpty) {
+      throw ArgumentError('There are no tabs.');
+    }
+    if (oldIndex < 0 || oldIndex >= _tabs.length) {
+      throw ArgumentError('Index out of range.', 'oldIndex');
+    }
+    if (newIndex < 0 || newIndex >= _tabs.length) {
+      throw ArgumentError('Index out of range.', 'newIndex');
+    }
+    if (oldIndex != newIndex) {
+      TabData? selectedTab;
+      if (_selectedIndex != null) {
+        selectedTab = _tabs[_selectedIndex!];
+      }
+
+      TabData tab = _tabs.removeAt(oldIndex);
+      _tabs.insert(newIndex, tab);
+      if (selectedTab != null) {
+        _selectedIndex = _tabs.indexOf(selectedTab);
+      }
+      notifyListeners();
+      if (onReorder != null) {
+        onReorder!(oldIndex, newIndex);
+      }
+    }
+  }
+
   /// Inserts [TabData] at position [index] in the [tabs].
   ///
   /// The [index] value must be non-negative and no greater than [tabs.length].

pubspec.lock

@@ -177,5 +177,5 @@ packages:
     source: hosted
     version: "2.1.4"
 sdks:
-  dart: ">=2.18.0 <4.0.0"
+  dart: ">=2.18.0 <3.0.0"
   flutter: ">=1.17.0"

test/reorder_test.dart

@@ -0,0 +1,96 @@
+import 'package:flutter_test/flutter_test.dart';
+import 'package:tabbed_view/src/tab_data.dart';
+import 'package:tabbed_view/src/tabbed_view_controller.dart';
+
+void main() {
+  group('controller', () {
+    test('reorder', () {
+      int reorderCount = 0;
+      OnReorder onReorder = (int oldIndex, int newIndex) {
+        reorderCount++;
+      };
+
+      // initial order a,b,c,d
+      TabbedViewController controller = TabbedViewController([
+        TabData(text: 'a'),
+        TabData(text: 'b'),
+        TabData(text: 'c'),
+        TabData(text: 'd')
+      ], onReorder: onReorder);
+
+      expect(false, controller.tabs.isEmpty);
+      expect(4, controller.tabs.length);
+
+      expect('a', controller.tabs[0].text);
+      expect('b', controller.tabs[1].text);
+      expect('c', controller.tabs[2].text);
+      expect('d', controller.tabs[3].text);
+      expect('a', controller.selectedTab?.text);
+
+      // ignores
+      controller.reorderTab(0, 0);
+      expect(0, reorderCount);
+      expect('a', controller.tabs[0].text);
+      expect('b', controller.tabs[1].text);
+      expect('c', controller.tabs[2].text);
+      expect('d', controller.tabs[3].text);
+      expect('a', controller.selectedTab?.text);
+
+      // a,b,c,d => b,a,c,d
+      controller.reorderTab(0, 1);
+      expect(1, reorderCount);
+      expect('b', controller.tabs[0].text);
+      expect('a', controller.tabs[1].text);
+      expect('c', controller.tabs[2].text);
+      expect('d', controller.tabs[3].text);
+      expect('a', controller.selectedTab?.text);
+
+      // b,a,c,d => a,b,c,d
+      controller.reorderTab(1, 0);
+      expect(2, reorderCount);
+      expect('a', controller.tabs[0].text);
+      expect('b', controller.tabs[1].text);
+      expect('c', controller.tabs[2].text);
+      expect('d', controller.tabs[3].text);
+      expect('a', controller.selectedTab?.text);
+
+      // a,b,c,d => a,c,d,b
+      controller.reorderTab(1, 3);
+      expect(3, reorderCount);
+      expect('a', controller.tabs[0].text);
+      expect('c', controller.tabs[1].text);
+      expect('d', controller.tabs[2].text);
+      expect('b', controller.tabs[3].text);
+      expect('a', controller.selectedTab?.text);
+
+      controller.selectedIndex = 1;
+      expect('c', controller.selectedTab?.text);
+
+      // a,c,d,b => c,d,b,a
+      controller.reorderTab(0, 3);
+      expect(4, reorderCount);
+      expect('c', controller.tabs[0].text);
+      expect('d', controller.tabs[1].text);
+      expect('b', controller.tabs[2].text);
+      expect('a', controller.tabs[3].text);
+      expect('c', controller.selectedTab?.text);
+
+      expect(() => controller.reorderTab(-1, 1), indexOutOfRangeError());
+      expect(() => controller.reorderTab(1, 100), indexOutOfRangeError());
+      expect(() => controller.reorderTab(-1, 100), indexOutOfRangeError());
+
+      controller = TabbedViewController([]);
+      expect(() => controller.reorderTab(1, 2), emptyError());
+    });
+  });
+}
+
+Matcher indexOutOfRangeError() {
+  return throwsA(predicate(
+      (x) => x is ArgumentError && x.message == 'Index out of range.'));
+}
+
+Matcher emptyError() {
+  return throwsA(predicate(
+      (x) => x is ArgumentError && x.message == 'There are no tabs.'));
+}