adding packages

2026-01-15 14:38:46 -08:00
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+# undo
+
+[![Buy Me A Coffee](https://img.shields.io/badge/Donate-Buy%20Me%20A%20Coffee-yellow.svg)](https://www.buymeacoffee.com/rodydavis)
+[![Donate](https://img.shields.io/badge/Donate-PayPal-green.svg)](https://www.paypal.com/cgi-bin/webscr?cmd=_s-xclick&hosted_button_id=WSH3GVC49GNNJ)
+![github pages](https://github.com/rodydavis/undo/workflows/github%20pages/badge.svg)
+![tests](https://github.com/rodydavis/undo/workflows/test/badge.svg)
+[![GitHub stars](https://img.shields.io/github/stars/rodydavis/undo?color=blue)](https://github.com/rodydavis/undo)
+[![undo](https://img.shields.io/pub/v/undo.svg)](https://pub.dev/packages/undo)
+
+An undo redo library for Dart/Flutter. Forked from [here](https://github.com/Mixbook/undo.dart) and updated for Flutter. Demo can be viewed [here](https://rodydavis.github.io/undo/).
+
+## Usage
+
+Create an ChangeStack to store changes
+
+```dart
+import 'package:undo/undo.dart';
+	
+var changes = ChangeStack();
+```
+	
+Add new undo, redo commands using `ChangeStack.add()`. When a change is added, it calls the change's `execute()` method. Use `Change()` for simple inline changes.
+	
+```dart
+var count = 0;
+	
+changes.add(
+  Change(count, () => count++, (val) => count = val);
+  name: "Increase"
+);
+```
+
+Use `Change()` when changing a field on an object. This will store the field's old value so it can be reverted.
+
+```dart
+var person = new Person()
+    ..firstName = "John"
+    ..lastName = "Doe";
+
+changes.add(
+  Change(
+    person.firstName, 
+    () => person.firstName = "Jane",
+    (oldValue) = person.firstName = oldValue
+  )
+)
+```
+
+Undo a change with `undo()`.
+
+```dart
+print(person.firstName); // Jane
+changes.undo();
+print(person.firstName); // John
+```
+	
+Redo the change with `redo()`.
+
+```dart
+changes.redo();
+print(person.firstName); // Jane
+```
+
+### Simple Stack Example
+
+```dart
+
+class HomeScreen extends StatefulWidget {
+  @override
+  _HomeScreenState createState() => _HomeScreenState();
+}
+
+class _HomeScreenState extends State<HomeScreen> {
+  SimpleStack _controller;
+
+  @override
+  void initState() {
+    _controller = SimpleStack<int>(
+      0,
+      onUpdate: (val) {
+        if (mounted)
+          setState(() {
+            print('New Value -> $val');
+          });
+      },
+    );
+    super.initState();
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    final count = _controller.state;
+    return Scaffold(
+      appBar: AppBar(
+        title: Text('Undo/Redo Example'),
+      ),
+      body: Center(
+        child: Text('Count: $count'),
+      ),
+      bottomNavigationBar: BottomAppBar(
+        child: Row(
+          children: <Widget>[
+            IconButton(
+              icon: Icon(Icons.arrow_back),
+              onPressed: !_controller.canUndo
+                  ? null
+                  : () {
+                      if (mounted)
+                        setState(() {
+                          _controller.undo();
+                        });
+                    },
+            ),
+            IconButton(
+              icon: Icon(Icons.arrow_forward),
+              onPressed: !_controller.canRedo
+                  ? null
+                  : () {
+                      if (mounted)
+                        setState(() {
+                          _controller.redo();
+                        });
+                    },
+            ),
+          ],
+        ),
+      ),
+      floatingActionButtonLocation: FloatingActionButtonLocation.endDocked,
+      floatingActionButton: FloatingActionButton(
+        heroTag: ValueKey('add_button'),
+        child: Icon(Icons.add),
+        onPressed: () {
+          _controller.modify(count + 1);
+        },
+      ),
+    );
+  }
+}
+
+```