// make Undo, i.e. revert the object to its previous state
public bool Undo(bool storeSateteBeforOperation = false)
{
if (undoList.Count > 0)
{
// get the object state from the undo list
ObjectPropertyValuePair undoObject = undoList[0];
// suspend the object from notification
// otherwise we will be notified for an action which we perform and should be inserted in any list
undoObject.O.SuspendListener = true;
// revert to the state
var prevState = undoObject.SetState();
// after we execute the operation we won to resume the notifications
undoObject.O.SuspendListener = false;
// remove this state from undo list
undoList.Remove(undoObject);
// IF WE WANT TO SAVE CURRENT STATE
if (storeSateteBeforOperation)
{
this.AddToRedo(prevState);
}
// add this state to the redo list
this.AddToRedo(undoObject);
return(true);
}
return(false);
}
// this actually reverts to the state
/// <summary>
///
/// </summary>
/// <returns>returns the state before revert</returns>
public ObjectPropertyValuePair SetState()
{
ObjectPropertyValuePair prevState = this.GetStateFor(this);
// we get the meta data about the property based on the object type
// then get the corresponding PropertyDescriptor, which allows us to call its set method
objectsProperties[this.o.GetType()][this.property].SetValue(this.o, this.oldeValue);
return(prevState);
}
private void AddToList(ObjectPropertyValuePair item, List <ObjectPropertyValuePair> list)
{
// we want to keep the capacity of the list to 30 items
// but since this list should behave as stack we should remove the items from the bottom
if (list.Count >= capacity)
{
for (int i = capacity - 1; i < list.Count; i++)
{
list.RemoveAt(i);
}
}
list.Insert(0, item);
}
public bool Redo(bool storeSateteBeforOperation = false)
{
if (redoList.Count > 0)
{
ObjectPropertyValuePair redoObject = redoList[0];
redoObject.O.SuspendListener = true;
var prevState = redoObject.SetState();
redoObject.O.SuspendListener = false;
redoList.Remove(redoObject);
// IF WE WANT TO SAVE CURRENT STATE
if (storeSateteBeforOperation)
{
this.AddToUndo(prevState);
}
this.AddToUndo(redoObject);
return(true);
}
return(false);
}
private void RemoveObjectFromUndoReduManager(object sender)
{
// unsubscribe from the events
INotify followedObject = sender as INotify;
followedObject.OnNotifyPropertyChanging -= FollowedObject_NotifyPropertyChanging;
followedObject.OnDispose -= FollowedObject_OnDispose;
// remove the object from all lists
objects.Remove(sender);
// here we use LINQ query to find the object we need
ObjectPropertyValuePair followedObjectWrapper = this.undoList.FirstOrDefault(o => o.O.Equals(sender));
if (followedObjectWrapper != null)
{
this.undoList.Remove(followedObjectWrapper);
}
// here we use LINQ query to find the object we need
followedObjectWrapper = this.redoList.FirstOrDefault(o => o.O.Equals(sender));
if (followedObjectWrapper != null)
{
this.redoList.Remove(followedObjectWrapper);
}
}
private ObjectPropertyValuePair GetStateFor(ObjectPropertyValuePair state)
{
return(new ObjectPropertyValuePair(ref state.o, state.property));
}
// add item to the redo list
private void AddToRedo(ObjectPropertyValuePair item)
{
AddToList(item, redoList);
}
private ObjectPropertyValuePair GetStateFor(ObjectPropertyValuePair state)
{
return new ObjectPropertyValuePair(ref state.o, state.property);
}
// add item to the Undo list
private void AddToUndo(ObjectPropertyValuePair item)
{
AddToList(item, undoList);
}
private void AddToList(ObjectPropertyValuePair item, List<ObjectPropertyValuePair> list)
{
// we want to keep the capacity of the list to 30 items
// but since this list should behave as stack we should remove the items from the bottom
if (list.Count >= capacity)
{
for (int i = capacity-1; i < list.Count; i++)
{
list.RemoveAt(i);
}
}
list.Insert(0, item);
}
