/// <summary>
/// Handles changes to the content of a ColumnDefinition in a ReportColumnCollection controls.
/// </summary>
/// <param name="sender">The object that originated the event.</param>
/// <param name="collectionChangedEventArgs">The event arguments.</param>
private void HandleColumnChanged(object sender, ColumnChangedEventArgs columnChangedEventArgs)
{
// The object that generated this event is a ReportColumnCollection. The main idea here is to store the action on the proper stack so that it
// can be undone or redone if the need arises. Note that it is critical to tag the command with the state of Undoing or Redoing.
ReportGrid reportGrid = sender as ReportGrid;
// Two stacks maintain the state of undoing and redoing all actions within its scope. This will determine which commands will need to execute to
// undo a given action. The actual act of undoing an operation will happen when the commands that are placed on the stacks here are executed.
switch (columnChangedEventArgs.UndoAction)
{
case UndoAction.Create:
// The act of creating an 'Undo' operation (as opposed to simply playing it back) will clear the Redo stack. That is, once a user udpates the
// user interface, it is no longer possible to replay the stack forward.
this.undoManager.RedoStack.Clear();
this.undoManager.UndoStack.Push(new CommandArgumentPair(UndoColumn, reportGrid, columnChangedEventArgs, UndoAction.Undo));
break;
case UndoAction.Redo:
// If the actions are being played forward, a command needs to be put back on the Undo stack in order to play it backwards.
this.undoManager.UndoStack.Push(new CommandArgumentPair(UndoColumn, reportGrid, columnChangedEventArgs, UndoAction.Undo));
break;
case UndoAction.Undo:
// When playing a set of actions backwards, those actions are popped off the Undo stack. This, in turn, will push those same actions onto the
// Redo stack so the operations can be played forward.
this.undoManager.RedoStack.Push(new CommandArgumentPair(UndoColumn, reportGrid, columnChangedEventArgs, UndoAction.Redo));
break;
}
}
/// <summary>
/// Undoes the most recent undo command on the stack.
/// </summary>
/// <param name="dependencyObject">The target of the undo operation.</param>
private void UndoColumn(object sender, GenericEventArgs genericEventArgs)
{
// Extract the specific arguments from the generic arguments
ReportGrid reportGrid = (ReportGrid)genericEventArgs.Arguments[0];
ColumnChangedEventArgs columnChangedEventArgs = (ColumnChangedEventArgs)genericEventArgs.Arguments[1];
UndoAction undoAction = (UndoAction)genericEventArgs.Arguments[2];
// This will undo a change to the width of a column.
if (columnChangedEventArgs.DependencyProperty == ReportColumn.WidthProperty)
{
reportGrid.reportColumnCollection.SetColumnWidth(columnChangedEventArgs.ColumnDefinition, (Double)columnChangedEventArgs.OldValue, undoAction);
}
}
