/// <summary>
/// Called when the command binding is executed.
/// </summary>
internal void HandleExecuted(DependencyObject element, ICommand command, Object parameter, ExecutedRoutedEventData data, Boolean preview)
{
if (data.Handled)
{
return;
}
var handler = preview ? PreviewExecuted : Executed;
if (handler != null)
{
var canExecuteData = CanExecuteRoutedEventData.Retrieve(data.Source as DependencyObject, autorelease: false);
try
{
HandleCanExecute(element, command, parameter, canExecuteData, false);
if (canExecuteData.CanExecute)
{
handler(element, command, parameter, data);
data.Handled = true;
}
}
finally
{
canExecuteData.Release();
}
}
}
/// <summary>
/// Determines whether the command can be executed.
/// </summary>
/// <param name="view">The view within which the command is being executed.</param>
/// <param name="parameter">The command parameter, or <see langword="null"/> if the command
/// does not require a parameter.</param>
/// <param name="valparameter">The command value parameter, or <see langword="null"/> if the command
/// does not require a value parameter. This parameter is intended for use in internal micro-optimizations and
/// will appear as one of the fields in the routed event data.</param>
/// <param name="target">The element within <paramref name="view"/> at which to begin
/// searching for command handlers.</param>
/// <param name="continue">A value indicating whether command routing should continue.</param>
/// <returns><see langword="true"/> if the command can be executed; otherwise, <see langword="false"/>.</returns>
public Boolean CanExecute(PresentationFoundationView view, Object parameter, PrimitiveUnion?valparameter, IInputElement target, out Boolean @continue)
{
Contract.Require(view, nameof(view));
var uiElement = target as UIElement;
if (uiElement != null && uiElement.View != view)
{
throw new ArgumentException(PresentationStrings.ElementDoesNotBelongToView);
}
if (uiElement != null)
{
var data = CanExecuteRoutedEventData.Retrieve(this, valparameter, autorelease: false);
try
{
var evtPreview = EventManager.GetInvocationDelegate <UpfCanExecuteRoutedEventHandler>(CommandManager.PreviewCanExecuteEvent);
evtPreview(uiElement, this, parameter, data);
if (!data.Handled)
{
var evt = EventManager.GetInvocationDelegate <UpfCanExecuteRoutedEventHandler>(CommandManager.CanExecuteEvent);
evt(uiElement, this, parameter, data);
}
@continue = data.ContinueRouting;
return(data.CanExecute);
}
finally
{
data.Release();
}
}
else
{
@continue = false;
return(false);
}
}
/// <summary> /// Raises the <see cref="CanExecute"/> event. /// </summary> private void RaiseCanExecute(DependencyObject element, ICommand command, Object parameters, CanExecuteRoutedEventData data) => CanExecute?.Invoke(element, command, parameters, data);
/// <summary>
/// Called when the command binding is being queried to determine whether it can execute.
/// </summary>
internal void HandleCanExecute(DependencyObject element, ICommand command, Object parameter, CanExecuteRoutedEventData data, Boolean preview)
{
if (data.Handled)
{
return;
}
if (preview)
{
if (PreviewCanExecute != null)
{
PreviewCanExecute(element, command, parameter, data);
if (data.CanExecute)
{
data.Handled = true;
}
}
}
else
{
if (CanExecute != null)
{
CanExecute(element, command, parameter, data);
if (data.CanExecute)
{
data.Handled = true;
}
}
else
{
if (!data.CanExecute && Executed != null)
{
data.CanExecute = true;
data.Handled = true;
}
}
}
}
