Merge pull request #335 from kekekeks/textbox-undo-redo

Implemented undo/redo for TextBox

src/Perspex.Base/Perspex.Base.csproj

@@ -85,6 +85,7 @@
     <Compile Include="Utilities\MathUtilities.cs" />
     <Compile Include="Utilities\TypeUtilities.cs" />
     <Compile Include="Utilities\WeakSubscriptionManager.cs" />
+    <Compile Include="Utilities\WeakTimer.cs" />
   </ItemGroup>
   <ItemGroup>
     <Reference Include="JetBrains.Annotations.PCL328, Version=9.2.0.0, Culture=neutral, PublicKeyToken=1010a0d8d6380325, processorArchitecture=MSIL">

src/Perspex.Base/Utilities/WeakTimer.cs

@@ -0,0 +1,55 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+using Perspex.Threading;
+
+namespace Perspex.Utilities
+{
+    public class WeakTimer
+    {
+        public interface IWeakTimerSubscriber
+        {
+            bool Tick();
+        }
+
+        private readonly WeakReference<IWeakTimerSubscriber> _subscriber;
+        private DispatcherTimer _timer;
+
+        public WeakTimer(IWeakTimerSubscriber subscriber)
+        {
+            _subscriber = new WeakReference<IWeakTimerSubscriber>(subscriber);
+            _timer = new DispatcherTimer();
+            
+            _timer.Tick += delegate { OnTick(); };
+            _timer.Start();
+        }
+
+        private void OnTick()
+        {
+            IWeakTimerSubscriber subscriber;
+            if (!_subscriber.TryGetTarget(out subscriber) || !subscriber.Tick())
+                Stop();
+        }
+
+        public TimeSpan Interval
+        {
+            get { return _timer.Interval; }
+            set { _timer.Interval = value; }
+        }
+
+        public void Start() => _timer.Start();
+        
+        public void Stop() => _timer.Stop();
+
+
+        public static WeakTimer StartWeakTimer(IWeakTimerSubscriber subscriber, TimeSpan interval)
+        {
+            var timer = new WeakTimer(subscriber) {Interval = interval};
+            timer.Start();
+            return timer;
+        }
+
+    }
+}

src/Perspex.Controls/Perspex.Controls.csproj

@@ -148,6 +148,7 @@
     <Compile Include="Utils\StringUtils.cs" />
     <Compile Include="TopLevel.cs" />
     <Compile Include="Primitives\PopupRoot.cs" />
+    <Compile Include="Utils\UndoRedoHelper.cs" />
     <Compile Include="Window.cs" />
     <Compile Include="RowDefinition.cs" />
     <Compile Include="RowDefinitions.cs" />
@@ -173,6 +174,10 @@
     <Compile Include="WrapPanel.cs" />
   </ItemGroup>
   <ItemGroup>
+    <Reference Include="JetBrains.Annotations.PCL328, Version=9.2.0.0, Culture=neutral, PublicKeyToken=1010a0d8d6380325, processorArchitecture=MSIL">
+      <HintPath>..\..\packages\JetBrains.Annotations.9.2.0\lib\portable-net4+sl5+netcore45+wpa81+wp8+MonoAndroid1+MonoTouch1\JetBrains.Annotations.PCL328.dll</HintPath>
+      <Private>True</Private>
+    </Reference>
     <Reference Include="System.Reactive.Core">
       <HintPath>..\..\packages\Rx-Core.2.2.5\lib\portable-windows8+net45+wp8\System.Reactive.Core.dll</HintPath>
     </Reference>

src/Perspex.Controls/TextBox.cs

@@ -17,7 +17,7 @@ using Perspex.Metadata;
 
 namespace Perspex.Controls
 {
-    public class TextBox : TemplatedControl
+    public class TextBox : TemplatedControl, UndoRedoHelper<TextBox.UndoRedoState>.IUndoRedoHost
     {
         public static readonly PerspexProperty<bool> AcceptsReturnProperty =
             PerspexProperty.Register<TextBox, bool>("AcceptsReturn");
@@ -49,7 +49,22 @@ namespace Perspex.Controls
         public static readonly PerspexProperty<bool> UseFloatingWatermarkProperty =
             PerspexProperty.Register<TextBox, bool>("UseFloatingWatermark");
 
+        struct UndoRedoState : IEquatable<UndoRedoState>
+        {
+            public string Text { get; }
+            public int CaretPosition { get; }
+
+            public UndoRedoState(string text, int caretPosition)
+            {
+                Text = text;
+                CaretPosition = caretPosition;
+            }
+
+            public bool Equals(UndoRedoState other) => ReferenceEquals(Text, other.Text) || Equals(Text, other.Text);
+        }
+
         private TextPresenter _presenter;
+        private UndoRedoHelper<UndoRedoState> _undoRedoHelper;
 
         static TextBox()
         {
@@ -73,6 +88,7 @@ namespace Perspex.Controls
                 ScrollViewer.HorizontalScrollBarVisibilityProperty,
                 horizontalScrollBarVisibility,
                 BindingPriority.Style);
+            _undoRedoHelper = new UndoRedoHelper<UndoRedoState>(this);
         }
 
         public bool AcceptsReturn
@@ -90,7 +106,12 @@ namespace Perspex.Controls
         public int CaretIndex
         {
             get { return GetValue(CaretIndexProperty); }
-            set { SetValue(CaretIndexProperty, value); }
+            set
+            {
+                SetValue(CaretIndexProperty, value);
+                if (_undoRedoHelper.IsLastState && _undoRedoHelper.LastState.Text == Text)
+                    _undoRedoHelper.UpdateLastState();
+            }
         }
 
         public int SelectionStart
@@ -173,6 +194,7 @@ namespace Perspex.Controls
                 Text = text.Substring(0, caretIndex) + input + text.Substring(caretIndex);
                 CaretIndex += input.Length;
                 SelectionStart = SelectionEnd = CaretIndex;
+                _undoRedoHelper.DiscardRedo();
             }
         }
 
@@ -189,7 +211,7 @@ namespace Perspex.Controls
             {
                 return;
             }
-
+            _undoRedoHelper.Snapshot();
             HandleTextInput(text);
         }
 
@@ -223,6 +245,16 @@ namespace Perspex.Controls
                         Paste();
                     }
 
+                    break;
+                case Key.Z:
+                    if (modifiers == InputModifiers.Control)
+                        _undoRedoHelper.Undo();
+
+                    break;
+                case Key.Y:
+                    if (modifiers == InputModifiers.Control)
+                        _undoRedoHelper.Redo();
+
                     break;
                 case Key.Left:
                     MoveHorizontal(-1, modifiers);
@@ -524,5 +556,15 @@ namespace Perspex.Controls
 
             return i;
         }
+
+        UndoRedoState UndoRedoHelper<UndoRedoState>.IUndoRedoHost.UndoRedoState
+        {
+            get { return new UndoRedoState(Text, CaretIndex); }
+            set
+            {
+                Text = value.Text;
+                SelectionStart = SelectionEnd = CaretIndex = value.CaretPosition;
+            }
+        }
     }
 }

src/Perspex.Controls/Utils/UndoRedoHelper.cs

@@ -0,0 +1,89 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+using JetBrains.Annotations;
+using Perspex.Utilities;
+
+namespace Perspex.Controls.Utils
+{
+    class UndoRedoHelper<TState> : WeakTimer.IWeakTimerSubscriber where TState : IEquatable<TState>
+    {
+        private readonly IUndoRedoHost _host;
+
+        public interface IUndoRedoHost
+        {
+             TState UndoRedoState { get; set; }
+        }
+        
+
+
+        private readonly LinkedList<TState> _states = new LinkedList<TState>();
+
+        [NotNull]
+        private LinkedListNode<TState> _currentNode;
+
+        public int Limit { get; set; } = 10;
+
+        public UndoRedoHelper(IUndoRedoHost host)
+        {
+            _host = host;
+            _states.AddFirst(_host.UndoRedoState);
+            _currentNode = _states.First;
+            WeakTimer.StartWeakTimer(this, new TimeSpan(0, 0, 1));
+
+        }
+
+        public void Undo()
+        {
+            _host.UndoRedoState= (_currentNode = _currentNode?.Previous ?? _currentNode).Value;
+        }
+
+        public bool IsLastState => _currentNode.Next == null;
+
+        public void UpdateLastState(TState state)
+        {
+            _states.Last.Value = state;
+        }
+
+        public void UpdateLastState()
+        {
+            _states.Last.Value = _host.UndoRedoState;
+        }
+
+        public TState LastState => _currentNode.Value;
+
+        public void DiscardRedo()
+        {
+            //Linked list sucks, so we are doing this
+            while (_currentNode.Next != null)
+                _states.Remove(_currentNode.Next);
+        }
+
+        public void Redo()
+        {
+            _host.UndoRedoState = (_currentNode = _currentNode?.Next ?? _currentNode).Value;
+        }
+
+        public void Snapshot()
+        {
+            var current = _host.UndoRedoState;
+            if (!_currentNode.Value.Equals(current))
+            {
+                if(_currentNode.Next != null)
+                    DiscardRedo();
+                _states.AddLast(current);
+                _currentNode = _states.Last;
+                if(_states.Count > Limit)
+                    _states.RemoveFirst();
+            }
+        }
+
+        bool WeakTimer.IWeakTimerSubscriber.Tick()
+        {
+            Snapshot();
+            return true;
+        }
+    }
+}

src/Perspex.Controls/packages.config

@@ -1,5 +1,6 @@
 <?xml version="1.0" encoding="utf-8"?>
 <packages>
+  <package id="JetBrains.Annotations" version="9.2.0" targetFramework="portable45-net45+win8" />
   <package id="Rx-Core" version="2.2.5" targetFramework="portable-net45+win8" />
   <package id="Rx-Interfaces" version="2.2.5" targetFramework="portable-net45+win8" />
   <package id="Rx-Linq" version="2.2.5" targetFramework="portable-net45+win8" />