private MemoryStream GetRedoStream()
{
if (this.canRedo)
{
MemoryStream resStream = null;
int index = history.IndexOf(currentElement);
if (index == history.Count - 1)
{
currentElement = history.Last <HistoryElement>();
}
else
{
if (index == -1)
{
currentElement = history.First <HistoryElement>();
}
else
{
currentElement = history.ElementAt <HistoryElement>(index + 1);
}
}
resStream = currentElement.Stream;
return(resStream);
}
return(null);
}
private bool MakeSnapshot()
{
MemoryStream currState = new MemoryStream();
currState.Seek(0, SeekOrigin.Begin);
bool result = this.parent.SaveToHistory(currState);
currState.Seek(0, SeekOrigin.Begin);
//currState.Close();
if (!result)
{
return(false);
}
HistoryElement item = new HistoryElement(currState, false);
int index = -1;
index = history.IndexOf(currentElement);
if (index == history.Count - 1)
{
history.Add(item);
currentElement = item;
return(true);
}
history.RemoveRange(index + 1, (history.Count - index - 1));
history.Add(item);
currentElement = item;
return(true);
}
private MemoryStream GetUndoStream()
{
if (this.canUndo)
{
MemoryStream resStream = null;
int index = history.IndexOf(currentElement);
if (index <= 0)
{
resStream = currentElement.Stream;
}
if (index > 0)
{
currentElement = history.ElementAt <HistoryElement>(index - 1);
resStream = currentElement.Stream;
}
return(resStream);
}
return(null);
}