助手扩展方法

/// <summary>
/// Provides a set of static (Shared in Visual Basic) methods for starting a fluent expression on a <see cref="System.Windows.Form.Control"/> object.
/// </summary>
public static class ControlExtensions
{
    /// <summary>
    /// Starts a fluent expression that occurs when a key is pressed.
    /// </summary>
    /// <param name="control">The control on which the fluent keyboard expression is occuring.</param>
    /// <param name="keys">The key when it will happen.</param>
    /// <returns>A <see cref="KeyboardFluent"/> object that makes it possible to write a fluent expression.</returns>
    public static KeyboardFluent When(this Control control,Keys keys)
    {
        return new KeyboardFluent(control).When(keys);
    }
}

流利的课程

/// <summary>
/// Represents a fluent expression for handling keyboard event.
/// </summary>
public class KeyboardFluent
{
    /// <summary>
    /// The control on which the fluent keyboard expression is occuring.
    /// </summary>
    private Control control;

    /// <summary>
    /// The KeyDown and KeyUp handler.
    /// </summary>
    private KeyEventHandler keyHandler;

    /// <summary>
    /// Stores if the IsDown method was called and that the KeyDown event is registered.
    /// </summary>
    private bool isDownRegistered = false;

    /// <summary>
    /// Stores if the IsUp method was called and that the KeyUp event is registered.
    /// </summary>
    private bool isUpRegistered = false;

    /// <summary>
    /// The list of keys that will make the actions be executed when they are down or up.
    /// </summary>
    private List<Keys> triggerKeys;

    /// <summary>
    /// The modifiers keys that must be down at the same time than the trigger keys for the actions to be executed.
    /// </summary>
    private Keys modifiers;

    /// <summary>
    /// The list of actions that will be executed when the trigger keys and modifiers are down or up.
    /// </summary>
    private List<Action<object,KeyEventArgs>> actions;

    /// <summary>
    /// Initializes a new instance of the <see cref="KeyboardFluent"/> class.
    /// </summary>
    /// <param name="control">The control on which the fluent keyboard expression is occuring.</param>
    public KeyboardFluent(Control control)
    {
        this.control = control;
        this.triggerKeys = new List<Keys>();
        this.actions = new List<Action<object,KeyEventArgs>>();
        this.keyHandler = new KeyEventHandler(OnKeyHandler);
    }

    /// <summary>
    /// Handles the KeyDown or KeyUp event on the control.
    /// </summary>
    /// <param name="sender">The control on which the event is occuring.</param>
    /// <param name="e">A <see cref="KeyEventArgs"/> that gives information about the keyboard event.</param>
    private void OnKeyHandler(object sender,KeyEventArgs e)
    {
        if (this.triggerKeys.Contains(e.KeyCode) && e.Modifiers == this.modifiers)
        {
            this.actions.ForEach(action => action(sender,e));
        }
    }

    /// <summary>
    /// Makes the keyboard event occured when a key is pressed down.
    /// </summary>
    /// <returns>Returns itself to allow a fluent expression structure.</returns>
    public KeyboardFluent IsDown()
    {
        if (!isDownRegistered)
        {
            this.control.KeyDown += this.keyHandler;
            isDownRegistered = true;
        }
        return this;
    }

    /// <summary>
    /// Makes the keyboard event occured when a key is pressed up.
    /// </summary>
    /// <returns>Returns itself to allow a fluent expression structure.</returns>
    public KeyboardFluent IsUp()
    {
        if (!isUpRegistered)
        {
            this.control.KeyUp += this.keyHandler;
            isUpRegistered = true;
        }
        return this;
    }

    /// <summary>
    /// Creates a new trigger on a key.
    /// </summary>
    /// <param name="key">The key on which the actions will occur.</param>
    /// <returns>Returns itself to allow a fluent expression structure.</returns>
    public KeyboardFluent When(Keys key)
    {
        this.triggerKeys.Add(key);
        return this;
    }

    /// <summary>
    /// Adds a modifier filter that is checked before the action are executed.
    /// </summary>
    /// <param name="modifiers">The modifier key.</param>
    /// <returns>Returns itself to allow a fluent expression structure.</returns>
    public KeyboardFluent With(Keys modifiers)
    {
        this.modifiers |= modifiers;
        return this;
    }

    /// <summary>
    /// Executes the action when the specified keys and modified are either pressed down or up.
    /// </summary>
    /// <param name="action">The action to be executed.</param>
    /// <returns>Returns itself to allow a fluent expression structure.</returns>
    public KeyboardFluent Do(Action<object,KeyEventArgs> action)
    {
        this.actions.Add(action);
        return this;
    }
}

我现在可以打字了

public partial class Form1 : Form
{
    public Form1()
    {
        InitializeComponent();

        this.When(Keys.F).With(Keys.Control).IsDown().Do((sender,e) => MessageBox.Show(e.KeyData.ToString()));
    }
}

只有在Ctrl F关闭时它才会显示消息框.