using System using System Collections Generic using System Linq using

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using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Windows.Input;
using System.Windows;
using System.Reflection;
using System.Collections;
using System.Windows.Data;
using System.ComponentModel;
using System.Windows.Markup;
namespace MethodCommandNS
{
[ContentProperty("Arguments")]
public class MethodCommand
: Freezable, // Enable ElementName and DataContext bindings
ICommand,
INotifyPropertyChanged
{
// The name of the method to call on Invoke
public string MethodName { get; set; }
// When this is set, exceptions during invoke are caught, and the exception
// is set as the Exception property
[DefaultValue(true)]
public bool CatchExceptions { get; set; }
// If there is an exception during a command invoke, and CatchExceptions
// is set, this will have the exception object.
public Exception Exception
{
get { return _exception; }
private set
{
_exception = value;
FirePropertyChanged("Exception");
}
}
Exception _exception;
// This holds the arguments to be passed to the method.
// This is Freezable so that the DataContext and ElementName bindings
// can work correctly.
public FreezableCollection<MethodArgument> Arguments
{
get { return (FreezableCollection<MethodArgument>)GetValue(ArgumentsProperty); }
}
public static readonly DependencyProperty ArgumentsProperty =
DependencyProperty.Register("Arguments", typeof(FreezableCollection<MethodArgument>), typeof(MethodCommand), null);
// This is a private DP that's used to get the inherited DataContext
// (see it used in the MethodCommand constructor).
private static readonly DependencyProperty ElementDataContextProperty =
DependencyProperty.Register("ElementDataContext", typeof(object), typeof(MethodCommand), null);
// The Target property specifies the object on which to invoke the method.
// If this is null, invoke the method on the DataContext
public object Target
{
get { return (object)GetValue(TargetProperty); }
set { SetValue(TargetProperty, value); }
}
public static readonly DependencyProperty TargetProperty =
DependencyProperty.Register("Target", typeof(object), typeof(MethodCommand), null);
// Constructor
public MethodCommand()
{
// The Arguments property is read-only and never null
SetValue(ArgumentsProperty, new FreezableCollection<MethodArgument>());
// Set a default Binding onto the private ElementDataContextProperty.
// A default binding just binds to the inherited DataContext. This is how
// MethodCommand typically gets the object on which to invoke the method.
BindingOperations.SetBinding(
this,
ElementDataContextProperty,
new Binding());
// By default, catch exceptions that are raised by the method.
CatchExceptions = true;
}
// Fire the PropertyChanged event when the Exception property changes.
public event PropertyChangedEventHandler PropertyChanged;
void FirePropertyChanged(string propertyName)
{
if (PropertyChanged != null)
{
PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
}
}
// We need to implement this method because we're a Freezzable subtype.
protected override Freezable CreateInstanceCore()
{
throw new NotImplementedException();
}
// Implement the CanExecute members of ICommand
public event EventHandler CanExecuteChanged;
public bool CanExecute(object parameter)
{
// We'll always be enabled to be invokes.
return true;
}
// ICommand.Execute implementation. This version calls ExecuteImpl, which does the
// the actual call. But this method wraps that call in a try/finally, depending on
// the value of CatchExceptions.
public void Execute(object parameter)
{
// Clear out any exception of a former invocation.
Exception = null;
if (CatchExceptions)
{
// Invoke the method in a try/finally
try
{
ExecuteImpl(parameter);
}
catch (Exception e)
{
// Any exceptions will likely come back as a
// TargetInvocationException, but the original exception
// is more interesting.
if (e is TargetInvocationException)
{
if (e.InnerException != null)
Exception = e.InnerException;
else
Exception = e;
}
else
Exception = e;
}
}
// Otherwise, CatchExceptions isn't set, so just forward the call
else
{
ExecuteImpl(parameter);
}
}
// ExecuteImpl is where we actually invoke the method.
void ExecuteImpl(object parameter)
{
// See if the Target property is set
object target = Target;
if (target == null)
{
// If not, look for an inherited DataContext
target = GetValue(ElementDataContextProperty);
}
// We must have a target, either from Target or DataContext
if (target == null)
{
throw new InvalidOperationException("MethodCommand target not found (must set either Target or DataContext)");
}
// Get the method to be called. Note that this doesn't support
// overloaded methods, but it could be updated to do so.
MethodInfo methodInfo = target.GetType().GetMethod(MethodName);
if (methodInfo == null)
{
throw new InvalidOperationException("Method '" + MethodName + "' couldn't be found on type '" + target.GetType().Name + "'");
}
// Copy the Arguments to an array
object[] arguments = new object[Arguments.Count];
for (int i = 0; i < Arguments.Count; i++)
arguments[i] = Arguments[i].Value;
// Invoke the method
methodInfo.Invoke(target, arguments);
}
}
// The MethodArgument class plugs into MethodCommand.Arguments
public class MethodArgument
: Freezable // Enable ElementName and DataContext bindings
{
public MethodArgument() { }
// The value of a method argument
public object Value
{
get { return (object)GetValue(ValueProperty); }
set { SetValue(ValueProperty, value); }
}
public static readonly DependencyProperty ValueProperty =
DependencyProperty.Register("Value", typeof(object), typeof(MethodArgument), null);
// We need to implement this method since we are a subtype of Freezable. But since
// we don't need to support cloning, we won't implement it.
protected override Freezable CreateInstanceCore()
{
throw new NotImplementedException();
}
}
}