/// <summary>
/// Handles a change to the undo manager for a given dependency object.
/// </summary>
/// <param name="dependencyObject">The target object for this attached property.</param>
/// <param name="dependencyPropertyChangedEventArgs">The event parameters.</param>
private static void OnUndoScopeChanged(DependencyObject dependencyObject, DependencyPropertyChangedEventArgs dependencyPropertyChangedEventArgs)
{
// This will remove the high level handlers for the root node in the UndoManager scope.
if (dependencyPropertyChangedEventArgs.OldValue is UndoManager)
{
// This is the manager that was previously associated with the root of the Undo Scope.
UndoManager undoManager = dependencyPropertyChangedEventArgs.OldValue as UndoManager;
// This will remove a handler for the mouse focus events.
undoManager.focusUndo.Unregister(dependencyObject);
// This will remove the UndoManager from all the child controls.
dependencyObject.ClearValue(UndoManager.UndoManagerProperty);
// This will remove the handlers for the undo/redo operations for the given undo manager.
if (dependencyObject is FrameworkElement)
{
FrameworkElement frameworkElement = dependencyObject as FrameworkElement;
frameworkElement.RemoveHandler(CommandManager.PreviewExecutedEvent, new ExecutedRoutedEventHandler(undoManager.OnCommand));
}
//// This will remove the handlers for the undo/redo operations for the given undo manager.
if (dependencyObject is FrameworkContentElement)
{
FrameworkContentElement frameworkContentElement = dependencyObject as FrameworkContentElement;
frameworkContentElement.RemoveHandler(CommandManager.PreviewExecutedEvent, new ExecutedRoutedEventHandler(undoManager.OnCommand));
}
}
// This will add the high level handlers for the root node in the UndoManager scope.
if (dependencyPropertyChangedEventArgs.NewValue is UndoManager)
{
// This is the manager that will be used for this Undo Scope to manage the Undo and Redo operations.
UndoManager undoManager = dependencyPropertyChangedEventArgs.NewValue as UndoManager;
// This will add a handler for the mouse focus events.
undoManager.focusUndo.Register(dependencyObject);
// This adds the Undo Manager to all the child windows in the scope of this user interface element which forms
// the root of the scope.
dependencyObject.SetValue(UndoManager.UndoManagerProperty, undoManager);
// This will add the handlers for the undo/redo operations for the given undo manager.
if (dependencyObject is FrameworkElement)
{
FrameworkElement frameworkElement = dependencyObject as FrameworkElement;
frameworkElement.AddHandler(CommandManager.PreviewExecutedEvent, new ExecutedRoutedEventHandler(undoManager.OnCommand), true);
}
//// This will add the handlers for the undo/redo operations for the given undo manager.
if (dependencyObject is FrameworkContentElement)
{
FrameworkContentElement frameworkContentElement = dependencyObject as FrameworkContentElement;
frameworkContentElement.AddHandler(CommandManager.PreviewExecutedEvent, new ExecutedRoutedEventHandler(undoManager.OnCommand), true);
}
}
}
/// <summary>
/// Removes this object from the chain of events that notify listeners of changes to the content.
/// </summary>
/// <param name="dependencyObject">The target element that will no longer be registered for state change events.</param>
public override void Unregister(DependencyObject dependencyObject)
{
// This will remove the handler for the mouse focus events.
if (dependencyObject is FrameworkElement)
{
FrameworkElement frameworkElement = dependencyObject as FrameworkElement;
frameworkElement.RemoveHandler(FrameworkElement.LostFocusEvent, new RoutedEventHandler(FocusHandler));
}
// This will remove the handler for the mouse focus events.
if (dependencyObject is FrameworkContentElement)
{
FrameworkContentElement frameworkContentElement = dependencyObject as FrameworkContentElement;
frameworkContentElement.RemoveHandler(FrameworkContentElement.LostFocusEvent, new RoutedEventHandler(FocusHandler));
}
}
/// <summary>
/// Handles a change to the undo manager for a given dependency object.
/// </summary>
/// <param name="dependencyObject">The target object for this attached property.</param>
/// <param name="dependencyPropertyChangedEventArgs">The event parameters.</param>
static void OnUndoScopeChanged(DependencyObject dependencyObject, DependencyPropertyChangedEventArgs dependencyPropertyChangedEventArgs)
{
// Validate the parameters.
if (dependencyObject == null)
{
throw new ArgumentNullException("dependencyObject");
}
if (dependencyPropertyChangedEventArgs == null)
{
throw new ArgumentNullException("dependencyPropertyChangedEventArgs");
}
// Extract the specific arguments from the generic ones.
UndoManager oldUndoManager = dependencyPropertyChangedEventArgs.OldValue as UndoManager;
UndoManager newUndoManager = dependencyPropertyChangedEventArgs.NewValue as UndoManager;
FrameworkElement frameworkElement = dependencyObject as FrameworkElement;
FrameworkContentElement frameworkContentElement = dependencyObject as FrameworkContentElement;
// This is the manager that was previously associated with the root of the Undo Scope.
if (oldUndoManager != null)
{
// This will remove a handler for the mouse focus events.
oldUndoManager.focusUndo.Unregister(dependencyObject);
// This will remove the UndoManager from all the child controls.
dependencyObject.ClearValue(UndoManager.UndoManagerProperty);
// This will remove the handlers for the undo/redo operations for the given undo manager.
if (frameworkElement != null)
{
frameworkElement.RemoveHandler(CommandManager.PreviewExecutedEvent, new ExecutedRoutedEventHandler(oldUndoManager.OnCommand));
}
// This will remove the handlers for the undo/redo operations for the given undo manager.
if (frameworkContentElement != null)
{
frameworkContentElement.RemoveHandler(CommandManager.PreviewExecutedEvent, new ExecutedRoutedEventHandler(oldUndoManager.OnCommand));
}
}
// This will add the high level handlers for the root node in the UndoManager scope.
if (newUndoManager != null)
{
// This will add a handler for the mouse focus events.
newUndoManager.focusUndo.Register(dependencyObject);
// This adds the Undo Manager to all the child windows in the scope of this user interface element which forms
// the root of the scope.
dependencyObject.SetValue(UndoManager.UndoManagerProperty, newUndoManager);
// This will add the handlers for the undo/redo operations for the given undo manager.
if (frameworkElement != null)
{
frameworkElement.AddHandler(CommandManager.PreviewExecutedEvent, new ExecutedRoutedEventHandler(newUndoManager.OnCommand), true);
}
//// This will add the handlers for the undo/redo operations for the given undo manager.
if (frameworkContentElement != null)
{
frameworkContentElement.AddHandler(CommandManager.PreviewExecutedEvent, new ExecutedRoutedEventHandler(newUndoManager.OnCommand), true);
}
}
}