I have a situation where I want to write custom command for framework element. Which I have done like below:
public class UndoRedoManager
{
private static FrameworkElement frameworkElement;
/// <summary>
/// UndoVMCommand Attached properrty.
/// </summary>
public static readonly DependencyProperty UndoVMCommandProperty =
DependencyProperty.RegisterAttached("UndoVMCommand", typeof(ICommand), typeof(UndoRedoManager), new FrameworkPropertyMetadata(UndoVmCommand, UndoVMCommand_PropertyChanged));
/// <summary>
/// UndoVMCommandProperty getter.
/// </summary>
/// <param name="obj"></param>
/// <returns></returns>
[AttachedPropertyBrowsableForChildren]
public static ICommand GetUndoVMCommand(DependencyObject obj)
{
return (ICommand)obj.GetValue(UndoVMCommandProperty);
}
/// <summary>
/// UndoVMCommandProperty setter.
/// </summary>
/// <param name="obj"></param>
/// <param name="value"></param>
public static void SetUndoVMCommand(DependencyObject obj, ICommand value)
{
obj.SetValue(UndoVMCommandProperty, value);
}
protected static void UndoVMCommand_PropertyChanged(DependencyObject obj, DependencyPropertyChangedEventArgs e)
{
var control = obj as FrameworkElement;
if (control != null)
{
if ((e.NewValue != null) && (e.OldValue == null))
{
frameworkElement = control;
}
else if ((e.NewValue == null) && (e.OldValue != null))
{
frameworkElement = null;
}
}
}
}
This I am attaching in the xaml thus:
<ItemsControl x:Name="graphControl" local:UndoRedoManager.UndoVMCommand="{Binding UndoCommand}">
......
</ItemsControl>
However, I want to fire this command on a button click.
<Button Content="Undo" CommandTarget="{Binding ElementName=graphControl}" Command="TheCommand" Margin="5"/>
Very much like
<Button Command="Copy" CommandTarget="{Binding ElementName=MyTextBox1}">Copy</Button>
So I have written the following:
public static RoutedUICommand undoVmCommand = new RoutedUICommand("TheCommand", "TheCommand", typeof(UndoRedoManager));
public static RoutedUICommand UndoVmCommand
{
get { return undoVmCommand; }
}
static UndoRedoManager()
{
CommandManager.RegisterClassCommandBinding(typeof(UndoRedoManager), new CommandBinding(undoVmCommand, ExecutedEventHandler_UndoVM, CanExecuteEventHandler_IfCanUndoVM));
}
private static void CanExecuteEventHandler_IfCanUndoVM(Object sender, CanExecuteRoutedEventArgs e)
{
FrameworkElement frmEle = sender as FrameworkElement;
e.CanExecute = false;
if (null != frmEle && frmEle.DataContext is ViewModelBase)
{
e.CanExecute = true;
//(frmEle.DataContext as GraphViewModel).CanUndo;
}
e.Handled = true;
}
public static void ExecutedEventHandler_UndoVM(Object sender, ExecutedRoutedEventArgs e)
{
FrameworkElement frmEle = sender as FrameworkElement;
if (null != frmEle && frmEle.DataContext is ViewModelBase)
{
(frmEle.DataContext as GraphViewModel).UndoCommand.Execute(null);
}
}
I am not getting it how wire that. Where should I declare the above routed command? Definitely I cannot do that in the FrameworkElement Class. IS there a way to attach that? I am sorry, if I havent been able to state the problem clearly. To put it in short simple way: If I were to write a "Copy" command for textbox in an attached manner, how can I do that?
EDIT: After @Erti's comment:
Now I have two classes, UndoRedoManager
public class UndoRedoManager
{
private static FrameworkElement frameworkElement;
/// <summary>
/// UndoVMCommand Attached properrty.
/// </summary>
public static readonly DependencyProperty UndoVMCommandProperty =
DependencyProperty.RegisterAttached("UndoVMCommand", typeof(ICommand), typeof(UndoRedoManager), new FrameworkPropertyMetadata(StaticCommand.UndoVmCommand, UndoVMCommand_PropertyChanged));
/// <summary>
/// UndoVMCommandProperty getter.
/// </summary>
/// <param name="obj"></param>
/// <returns></returns>
[AttachedPropertyBrowsableForChildren]
public static ICommand GetUndoVMCommand(DependencyObject obj)
{
return (ICommand)obj.GetValue(UndoVMCommandProperty);
}
/// <summary>
/// UndoVMCommandProperty setter.
/// </summary>
/// <param name="obj"></param>
/// <param name="value"></param>
public static void SetUndoVMCommand(DependencyObject obj, ICommand value)
{
obj.SetValue(UndoVMCommandProperty, value);
}
protected static void UndoVMCommand_PropertyChanged(DependencyObject obj, DependencyPropertyChangedEventArgs e)
{
var control = obj as FrameworkElement;
if (control != null)
{
if ((e.NewValue != null) && (e.OldValue == null))
{
frameworkElement = control;
}
else if ((e.NewValue == null) && (e.OldValue != null))
{
frameworkElement = null;
}
}
}
}
Please note the default value passed in the PropertyMetadata while registering the dependency property. In xaml I am using it as:
<ItemsControl x:Name="graphControl" local:UndoRedoManager.UndoVMCommand="{Binding UndoCommand}"/>
Another is the StaticCommand class:
public class StaticCommand
{
public static RoutedUICommand undoVmCommand = new RoutedUICommand("TheCommand", "TheCommand", typeof(UndoRedoManager));
public static RoutedUICommand UndoVmCommand
{
get { return undoVmCommand; }
}
static StaticCommand()
{
CommandManager.RegisterClassCommandBinding(typeof(StaticCommand), new CommandBinding(undoVmCommand, ExecutedEventHandler_UndoVM, CanExecuteEventHandler_IfCanUndoVM));
}
private static void CanExecuteEventHandler_IfCanUndoVM(Object sender, CanExecuteRoutedEventArgs e)
{
//This is not getting hit.
e.CanExecute = true;
e.Handled = true;
}
public static void ExecutedEventHandler_UndoVM(Object sender, ExecutedRoutedEventArgs e)
{
//I will do something here
}
}
In xaml I am using it as:
<Button Content="Undo" CommandTarget="{Binding ElementName=graphControl}" Command="{Binding Source={x:Static local:StaticCommand.UndoVmCommand}}" Margin="5"/>
But now the above button is not getting activated at all.
