If you use interfaces (especially for the listeners) it is much easier for other people to create mocks for unit tests. As a plus the tight coupling to a concrete implementation can be removed (partly).
e.g.:
/// <summary>
/// Common interface for handling hooks.
/// </summary>
public interface IHookListener
{
/// <summary>
/// Gets or Sets the enabled status of the Hook.
/// </summary>
/// <value>
/// <c>true</c> if the Hook is presently installed, activated, and will fire events; otherwise, <c>false</c> if the Hook is not part of the hook chain, and will not fire events.
/// </value>
bool Enabled { get; set; }
}
/// <summary>
/// This is an interface of monitoring keyboard activities.
/// </summary>
public interface IKeyboardHookListener : IHookListener
{
#region Public Events
/// <summary>
/// Occurs when a key is pressed.
/// </summary>
event KeyEventHandler KeyDown;
/// <summary>
/// Occurs when a key is pressed.
/// </summary>
/// <remarks>
/// Key events occur in the following order:
/// <list type="number">
/// <item>KeyDown</item>
/// <item>KeyPress</item>
/// <item>KeyUp</item>
/// </list>
/// The KeyPress event is not raised by non-character keys; however, the non-character keys do raise the KeyDown and KeyUp events.
/// Use the KeyChar property to sample keystrokes at run time and to consume or modify a subset of common keystrokes.
/// To handle keyboard events only in your application and not enable other applications to receive keyboard events,
/// set the <see cref="KeyPressEventArgs.Handled"/> property in your form's KeyPress event-handling method to <b>true</b>.
/// </remarks>
event KeyPressEventHandler KeyPress;
/// <summary>
/// Occurs when a key is released.
/// </summary>
event KeyEventHandler KeyUp;
#endregion
}
/// <summary>
/// This is an interface of monitoring all mouse activities.
/// </summary>
public interface IMouseHookListener : IHookListener
{
#region Public Events
/// <summary>
/// Occurs when a click was performed by the mouse.
/// </summary>
event MouseEventHandler MouseClick;
/// <summary>
/// Occurs when a mouse button is double-clicked.
/// </summary>
event MouseEventHandler MouseDoubleClick;
/// <summary>
/// Occurs when the mouse a mouse button is pressed.
/// </summary>
event MouseEventHandler MouseDown;
/// <summary>
/// Occurs when the mouse pointer is moved.
/// </summary>
event MouseEventHandler MouseMove;
/// <summary>
/// Occurs when a mouse button is released.
/// </summary>
event MouseEventHandler MouseUp;
/// <summary>
/// Occurs when the mouse wheel moves.
/// </summary>
event MouseEventHandler MouseWheel;
#endregion
}
