Start event handling

Event.cs

@@ -1,9 +1,95 @@
 namespace Terminal {
 
+    /// <summary>
+    /// The Key enumeration contains special encoding for some keys, but can also
+    /// encode all the unicode values that can be passed.   
+    /// </summary>
+    /// <remarks>
+    /// <para>
+    ///   If the SpecialMask is set, then the value is that of the special mask,
+    ///   otherwise, the value is the one of the lower bits (as extracted by CharMask)
+    /// </para>
+    /// <para>
+    ///   Control keys are the values between 1 and 26 corresponding to Control-A to Control-Z
+    /// </para>
+    /// </remarks>
+    public enum Key : uint {
+        CharMask = 0xfffff,
+        SpecialMask = 0xfff00000,
+        ControlA = 1,
+        ControlB,
+        ControlC,
+        ControlD,
+        ControlE,
+        ControlF,
+        ControlG,
+        ControlH,
+        ControlI,
+        Tab = ControlI,
+        ControlJ,
+        ControlK,
+        ControlL,
+        ControlM,
+        ControlN,
+        ControlO,
+        ControlP,
+        ControlQ,
+        ControlR,
+        ControlS,
+        ControlT,
+        ControlU,
+        ControlV,
+        ControlW,
+        ControlX,
+        ControlY,
+        ControlZ,
+        Esc = 27,
+        Space = 32,
+        Delete = 127,
+
+        AltMask = 0x80000000,
+
+        Backspace = 0x100000,
+        CursorUp,
+        CursorDown,
+        CursorLeft,
+        CursorRight,
+        PageUp,
+        PageDown,
+        Home,
+        End,
+        DeleteChar,
+        InsertChar,
+        F1,
+        F2,
+        F3,
+        F4,
+        F5,
+        F6,
+        F7,
+        F8,
+        F9,
+        F10,
+        BackTab,
+        Unknown
+    }
+
+    public struct KeyEvent {
+        public Key Key;
+        public int KeyValue => (int)KeyValue;
+        public bool IsAlt => (Key & Key.AltMask) != 0;
+        public bool IsCtrl => ((uint)Key >= 1) && ((uint)Key <= 26);
+
+        public KeyEvent (Key k)
+        {
+            Key = k;
+        }
+    }
+
     public class Event {
         public class Key : Event {
             public int Code { get; private set; }
-
+            public bool Alt { get; private set; }
             public Key (int code)
             {
                 Code = code;