I was wondering if the same thing could be done and ended writing a simple CommandManager that queries the registered commands (on the Application.Idle event) and uses databinding to change the Enabled state of the control
This is the code I'm using right now:
public class CommandManager: Component
{
private IList<ICommand> Commands { get; set; }
private IList<ICommandBinder> Binders { get; set; }
public CommandManager()
{
Commands = new List<ICommand>();
Binders = new List<ICommandBinder>
{
new ControlBinder(),
new MenuItemCommandBinder()
};
Application.Idle += UpdateCommandState;
}
private void UpdateCommandState(object sender, EventArgs e)
{
Commands.Do(c => c.Enabled);
}
public CommandManager Bind(ICommand command, IComponent component)
{
if (!Commands.Contains(command))
Commands.Add(command);
FindBinder(component).Bind(command, component);
return this;
}
protected ICommandBinder FindBinder(IComponent component)
{
var binder = GetBinderFor(component);
if (binder == null)
throw new Exception(string.Format("No binding found for component of type {0}", component.GetType().Name));
return binder;
}
private ICommandBinder GetBinderFor(IComponent component)
{
var type = component.GetType();
while (type != null)
{
var binder = Binders.FirstOrDefault(x => x.SourceType == type);
if (binder != null)
return binder;
type = type.BaseType;
}
return null;
}
protected override void Dispose(bool disposing)
{
if (disposing)
Application.Idle -= UpdateCommandState;
base.Dispose(disposing);
}
}
public static class Extensions
{
public static void Do<T>(this IEnumerable<T> @this, Func<T, object> lambda)
{
foreach (var item in @this)
lambda(item);
}
}
public abstract class CommandBinder<T> : ICommandBinder where T: IComponent
{
public Type SourceType
{
get { return typeof (T); }
}
public void Bind(ICommand command, object source)
{
Bind(command, (T) source);
}
protected abstract void Bind(ICommand command, T source);
}
public class ControlBinder: CommandBinder<Control>
{
protected override void Bind(ICommand command, Control source)
{
source.DataBindings.Add("Enabled", command, "Enabled");
source.DataBindings.Add("Text", command, "Name");
source.Click += (o, e) => command.Execute();
}
}
public class MenuItemCommandBinder : CommandBinder<ToolStripItem>
{
protected override void Bind(ICommand command, ToolStripItem source)
{
source.Text = command.Name;
source.Enabled = command.Enabled;
source.Click += (o, e) => command.Execute();
command.PropertyChanged += (o, e) => source.Enabled = command.Enabled;
}
}
and this is an exmaple of how to use it:
public partial class Form1 : Form
{
private CommandManager commandManager;
public ICommand CommandA { get; set; }
public ICommand CommandB { get; set; }
public bool condition;
public Form1()
{
InitializeComponent();
commandManager = new CommandManager();
CommandA = new DelegateCommand("Command 1", OnTrue, OnExecute);
CommandB = new DelegateCommand("Command 2", OnFalse, OnExecute);
commandManager.Bind(CommandA, button1);
commandManager.Bind(CommandB, button2);
commandManager.Bind(CommandA, command1ToolStripMenuItem);
commandManager.Bind(CommandB, command2ToolStripMenuItem);
}
private bool OnFalse()
{
return !condition;
}
private bool OnTrue()
{
return condition;
}
private void OnExecute()
{
condition = !condition;
}
}
Also if you need the code, I blogged about it here
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