/
History.cs
188 lines (175 loc) · 5.89 KB
/
History.cs
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namespace UndoRedo
{
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Linq;
using System.Runtime.CompilerServices;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Controls.Primitives;
public class History : IHistory
{
private readonly Stack<HistoryPoint> _undoStack = new Stack<HistoryPoint>();
private readonly Stack<HistoryPoint> _redoStack = new Stack<HistoryPoint>();
private TimeSpan _mergeTime = TimeSpan.FromSeconds(1);
public event EventHandler OnClear;
public event EventHandler OnChanged;
public Stack<HistoryPoint> UndoStack
{
get
{
return _undoStack;
}
}
public Stack<HistoryPoint> RedoStack
{
get
{
return _redoStack;
}
}
public bool CanRedo
{
get
{
return _redoStack.Any();
}
}
public void Clear()
{
_undoStack.Clear();
_redoStack.Clear();
OnOnClear();
}
internal void Update(TextBoxHistoryPoint historyPoint)
{
var cv = _undoStack.FirstOrDefault(x => ReferenceEquals(x.Control, historyPoint.Control));
if (cv != null && Equals(cv.Value, historyPoint.Value))
return;
if (_redoStack.Any())
{
HistoryPoint redoPoint = _redoStack.Peek();
if (ReferenceEquals(redoPoint.Control, historyPoint.Control) && Equals(redoPoint.Value, historyPoint.Value))
return;
}
_undoStack.Push(historyPoint);
_redoStack.Clear();
OnOnChanged();
}
internal void Update(HistoryPoint historyPoint)
{
var cv = _undoStack.FirstOrDefault(x => x.UpdateReason != UpdateReason.DataUpdated && ReferenceEquals(x.Control, historyPoint.Control));
if (cv != null && Equals(cv.Value, historyPoint.Value))
return;
if (_redoStack.Any())
{
HistoryPoint redoPoint = _redoStack.Peek();
if (ReferenceEquals(redoPoint.Control, historyPoint.Control) && Equals(redoPoint.Value, historyPoint.Value))
return;
}
if (CanMerge(historyPoint, UndoStack, _mergeTime))
{
Merge(historyPoint, UndoStack, _mergeTime);
return;
}
_undoStack.Push(historyPoint);
_redoStack.Clear();
OnOnChanged();
}
internal void Update(Control control, object value, DependencyProperty property, UpdateReason reason)
{
var textBoxBase = control as TextBoxBase;
if (textBoxBase != null)
Update(new TextBoxHistoryPoint(textBoxBase, value, property, reason));
else
Update(new HistoryPoint(control, value, property, reason));
}
internal void Undo(Control control)
{
if (IsDirty(control))
{
var hp = _undoStack.First(x => ReferenceEquals(x.Control, control));
_redoStack.Push(hp.ToUndoPoint());
hp.Undo();
}
else
{
var hp = (_undoStack.Peek().UpdateReason != UpdateReason.DataUpdated)
? _undoStack.Pop()
: _undoStack.Peek();
_redoStack.Push(hp.ToUndoPoint());
hp.Undo();
}
OnOnChanged();
}
internal void Redo(Control control)
{
var hp = _redoStack.Pop();
_undoStack.Push(hp.ToRedoPoint());
hp.Redo();
OnOnChanged();
}
internal bool CanUndo(Control control)
{
if (IsDirty(control))
return true;
if (!_undoStack.Any())
return false;
HistoryPoint up = _undoStack.Peek();
if (up.UpdateReason != UpdateReason.DataUpdated)
return true;
return !Equals(up.Value, up.CurrentValue);
}
internal bool IsDirty(Control control)
{
if (control == null)
{
return false;
}
HistoryPoint up = _undoStack.FirstOrDefault(x => ReferenceEquals(x.Control, control));
if (up != null)
{
if (!Equals(up.Value, up.CurrentValue))
{
return true;
}
}
return false;
}
protected virtual void OnOnClear()
{
EventHandler handler = OnClear;
if (handler != null)
{
handler(this, EventArgs.Empty);
}
OnOnChanged();
}
protected virtual void OnOnChanged()
{
EventHandler handler = OnChanged;
if (handler != null)
{
handler(this, EventArgs.Empty);
}
}
private bool CanMerge(HistoryPoint newPoint, Stack<HistoryPoint> undostack, TimeSpan mergeTime)
{
if (!undostack.Any())
return false;
var hp = undostack.Peek();
if (!ReferenceEquals(hp.Control, newPoint.Control))
return false;
var dt = newPoint.Timestamp - hp.Timestamp;
return dt < mergeTime;
}
private void Merge(HistoryPoint newPoint, Stack<HistoryPoint> undostack, TimeSpan mergeTime)
{
if (!CanMerge(newPoint, undostack, mergeTime))
throw new InvalidOperationException("Cannot merge call CanMerge() before");
var hp = undostack.Pop();
undostack.Push(newPoint);
}
}
}