/// <summary>
/// Enabling undo/redo for changes to the strokes collection.
/// </summary>
void Strokes_StrokesChanged(object sender, StrokeCollectionChangedEventArgs e)
{
StrokeCollection added = new StrokeCollection(e.Added);
StrokeCollection removed = new StrokeCollection(e.Removed);
CommandItem item = new StrokesAddedOrRemovedCI(_cmdStack, MyInkCanvas.EditingMode, added, removed, _editingOperationCount);
_cmdStack.Enqueue(item);
}
public override bool Merge(CommandItem newitem)
{
StrokesAddedOrRemovedCI newitemx = newitem as StrokesAddedOrRemovedCI;
if (newitemx == null ||
newitemx._editingMode != _editingMode ||
newitemx._editingOperationCount != _editingOperationCount)
{
return(false);
}
// We only implement merging for repeated point-erase operations.
if (_editingMode != InkCanvasEditingMode.EraseByPoint)
{
return(false);
}
if (newitemx._editingMode != InkCanvasEditingMode.EraseByPoint)
{
return(false);
}
// Note: possible for point-erase to have hit intersection of >1 strokes!
// For each newly hit stroke, merge results into this command item.
foreach (Stroke doomed in newitemx._removed)
{
if (_added.Contains(doomed))
{
_added.Remove(doomed);
}
else
{
_removed.Add(doomed);
}
}
_added.Add(newitemx._added);
return(true);
}