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using System;
using System.Windows.Forms;
namespace IssueVision
{
// Commander-derived classes exist to hook up Windows Forms UI elements to
// Command objects using an adapter pattern. The adapter approach permits a
// single Command object to sink events from dissimilar ui elements, and to set
// state on dissimilar ui elements.
//
// This implementation provides Commanders for
// -menu items
// -toolbar buttons
//
// Commanders exhibit the Adapter pattern in two ways:
// - They adapt the different kinds of events fired by Clients (e.g. menu
// items and tool bar buttons) to invoke the Execute methods of their
// Commands.
// - They adapt the EnableChanged events fired by Commands to set the
// Enabled property of their Clients.
// base Commander class
public abstract class Commander
{
protected Command m_command;
protected abstract void HandleEnableChangedEvent(object sender, Command.EnableChangedEventArgs e);
protected Commander(Command command)
{
m_command = command;
m_command.EnableChanged += new Command.EnableChangedEventHandler(this.HandleEnableChangedEvent);
}
}
// MenuItemCommander class
public class MenuItemCommander : Commander
{
private MenuItem m_item;
protected MenuItemCommander(MenuItem item, Command command) : base(command)
{
m_item = item;
m_item.Click += new EventHandler(this.HandleUIEvent);
}
protected override void HandleEnableChangedEvent(object sender, Command.EnableChangedEventArgs e)
{
m_item.Enabled = e.IsEnabled;
}
private void HandleUIEvent(object sender, EventArgs e)
{
m_command.Execute();
}
// Connect is a shared (static) method that performs the task of adapting a menu
// item to a command. The commander exists only to wire up the two objects --
// it is not used further
public static void Connect(MenuItem item, Command command)
{
MenuItemCommander unused = new MenuItemCommander(item, command);
}
}
public class ToolBarButtonCommander : Commander
{
private ToolBarButton m_button;
protected ToolBarButtonCommander(ToolBarButton button, Command command) : base(command)
{
m_button = button;
button.Parent.ButtonClick += new ToolBarButtonClickEventHandler(this.HandleUIEvent);
}
protected override void HandleEnableChangedEvent(object sender, Command.EnableChangedEventArgs e)
{
m_button.Enabled = e.IsEnabled;
}
private void HandleUIEvent(object sender, ToolBarButtonClickEventArgs e)
{
if (m_button == e.Button)
{
m_command.Execute();
}
}
// Connect is a shared (static) method that performs the task of adapting a toolbar
// button to a command. The commander exists only to wire up the two objects --
// it is not used further
public static void Connect(ToolBarButton button, Command command)
{
ToolBarButtonCommander unused = new ToolBarButtonCommander(button, command);
}
}
}
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Weidong has been an information system professional since 1990. He has a Master's degree in Computer Science, and is currently a MCSD .NET