Fixes #2921 - MainLoop refactoring (#2922)

* Adds basic MainLoop unit tests

* Remove WinChange action from Curses

* Remove WinChange action from Curses

* Remove ProcessInput action from Windows MainLoop

* Simplified MainLoop/ConsoleDriver by making MainLoop internal and moving impt fns to Application

* Modernized Terminal resize events

* Modernized Terminal resize events

* Removed un used property

* for _isWindowsTerminal devenv->wininit; not sure what changed

* Modernized mouse/keyboard events (Action->EventHandler)

* Updated OnMouseEvent API docs

* Using WT_SESSION to detect WT

* removes hacky GetParentProcess

* Updates to fix #2634 (clear last line)

* removes hacky GetParentProcess2

* Addressed mac resize issue

* Addressed mac resize issue

* Removes ConsoleDriver.PrepareToRun, has Init return MainLoop

* Removes unneeded Attribute methods

* Removed GetProcesssName

* Removed GetProcesssName

* Refactored KeyEvent and KeyEventEventArgs into a single class

* Revert "Refactored KeyEvent and KeyEventEventArgs into a single class"

This reverts commit 88a0065.

* Fixed key repeat issue; reverted stupidity on 1049/1047 confusion

* Updated CSI API Docs

* merge

CONTRIBUTING.md

@@ -148,11 +148,11 @@ The [Microsoft .NET Framework Design Guidelines](https://docs.microsoft.com/en-u
 > ✔️ DO name event argument classes with the "EventArgs" suffix.
 
 1. We follow the naming guidelines provided in https://docs.microsoft.com/en-us/dotnet/standard/design-guidelines/names-of-type-members?redirectedfrom=MSDN
-2. We use the `event Action<T>` idiom.
+2. We use the `event EventHandler<T>` idiom.
 3. For public APIs, the class that can raise the event will implement:
    - A `virtual` event raising function, named as `OnEventToRaise`. Typical implementations will simply do a `EventToRaise?.Invoke(this, eventArgs)`.
-   - An `event` as in `public event Action<EventArgs> EventToRaise`
-   - Consumers of the event can do `theobject.EventToRaise += (args) => {};`
+   - An `event` as in `public event EventHandler<EventArgs> EventToRaise`
+   - Consumers of the event can do `theobject.EventToRaise += (sender, args) => {};`
    - Sub-classes of the class implementing `EventToRaise` can override `OnEventToRaise` as needed.
 4. Where possible, a subclass of `EventArgs` should be provided and the old and new state should be included. By doing this, event handler methods do not have to query the sender for state.
 

ReactiveExample/TerminalScheduler.cs

@@ -15,7 +15,7 @@ public override IDisposable Schedule<TState> (
 			IDisposable PostOnMainLoop() {
 				var composite = new CompositeDisposable(2);
 				var cancellation = new CancellationDisposable();
-				Application.MainLoop.Invoke (() => {
+				Application.Invoke (() => {
 					if (!cancellation.Token.IsCancellationRequested)
 						composite.Add(action(this, state));
 				});
@@ -25,11 +25,11 @@ IDisposable PostOnMainLoop() {
 
 			IDisposable PostOnMainLoopAsTimeout () {
 				var composite = new CompositeDisposable (2);
-				var timeout = Application.MainLoop.AddTimeout (dueTime, args => {
+				var timeout = Application.AddTimeout (dueTime, () => {
 					composite.Add(action (this, state));
 					return false;
 				});
-				composite.Add (Disposable.Create (() => Application.MainLoop.RemoveTimeout (timeout)));
+				composite.Add (Disposable.Create (() => Application.RemoveTimeout (timeout)));
 				return composite;
 			}
 

Terminal.Gui/Configuration/ConfigurationManager.cs

@@ -251,7 +251,7 @@ public static void OnUpdated ()
 
 	/// <summary>
 	/// Resets the state of <see cref="ConfigurationManager"/>. Should be called whenever a new app session
-	/// (e.g. in <see cref="Application.Init(ConsoleDriver, IMainLoopDriver)"/> starts. Called by <see cref="Load"/>
+	/// (e.g. in <see cref="Application.Init(ConsoleDriver)"/> starts. Called by <see cref="Load"/>
 	/// if the <c>reset</c> parameter is <see langword="true"/>.
 	/// </summary>
 	/// <remarks>

Terminal.Gui/ConsoleDrivers/ConsoleDriver.cs

@@ -9,7 +9,6 @@
 
 namespace Terminal.Gui;
 
-
 /// <summary>
 /// Base class for Terminal.Gui ConsoleDriver implementations.
 /// </summary>
@@ -32,20 +31,31 @@ public abstract class ConsoleDriver {
 	/// </summary>
 	internal static bool RunningUnitTests { get; set; }
 
+	#region Setup & Teardown
+
+	/// <summary>
+	/// Initializes the driver
+	/// </summary>
+	/// <returns>Returns an instance of <see cref="MainLoop"/> using the <see cref="IMainLoopDriver"/> for the driver.</returns>
+	internal abstract MainLoop Init ();
+
 	/// <summary>
-	/// Prepare the driver and set the key and mouse events handlers.
+	/// Ends the execution of the console driver.
 	/// </summary>
-	/// <param name="mainLoop">The main loop.</param>
-	/// <param name="keyHandler">The handler for ProcessKey</param>
-	/// <param name="keyDownHandler">The handler for key down events</param>
-	/// <param name="keyUpHandler">The handler for key up events</param>
-	/// <param name="mouseHandler">The handler for mouse events</param>
-	public abstract void PrepareToRun (MainLoop mainLoop, Action<KeyEvent> keyHandler, Action<KeyEvent> keyDownHandler, Action<KeyEvent> keyUpHandler, Action<MouseEvent> mouseHandler);
+	internal abstract void End ();
+
+	#endregion
 
 	/// <summary>
-	/// The handler fired when the terminal is resized.
+	/// The event fired when the terminal is resized.
 	/// </summary>
-	protected Action TerminalResized;
+	public event EventHandler<SizeChangedEventArgs> SizeChanged;
+
+	/// <summary>
+	/// Called when the terminal size changes. Fires the <see cref="SizeChanged"/> event.
+	/// </summary>
+	/// <param name="args"></param>
+	public void OnSizeChanged (SizeChangedEventArgs args) => SizeChanged?.Invoke (this, args);
 
 	/// <summary>
 	/// The number of columns visible in the terminal.
@@ -90,12 +100,6 @@ public abstract class ConsoleDriver {
 	///// </summary>
 	public Cell [,] Contents { get; internal set; }
 
-	/// <summary>
-	/// Initializes the driver
-	/// </summary>
-	/// <param name="terminalResized">Method to invoke when the terminal is resized.</param>
-	public abstract void Init (Action terminalResized);
-
 	/// <summary>
 	/// Gets the column last set by <see cref="Move"/>. <see cref="Col"/> and <see cref="Row"/>
 	/// are used by <see cref="AddRune(Rune)"/> and <see cref="AddStr"/> to determine where to add content.
@@ -411,23 +415,14 @@ public Attribute SetAttribute (Attribute c)
 		return prevAttribute;
 	}
 
-	/// <summary>
-	/// Make the attribute for the foreground and background colors.
-	/// </summary>
-	/// <param name="fore">Foreground.</param>
-	/// <param name="back">Background.</param>
-	/// <returns></returns>
-	public virtual Attribute MakeAttribute (Color fore, Color back)
-	{
-		return MakeColor (fore, back);
-	}
-
 	/// <summary>
 	/// Gets the current <see cref="Attribute"/>.
 	/// </summary>
 	/// <returns>The current attribute.</returns>
 	public Attribute GetAttribute () => CurrentAttribute;
-
+
+	// TODO: This is only overridden by CursesDriver. Once CursesDriver supports 24-bit color, this virtual method can be
+	// removed (and Attribute can lose the platformColor property).
 	/// <summary>
 	/// Makes an <see cref="Attribute"/>.
 	/// </summary>
@@ -445,6 +440,64 @@ public virtual Attribute MakeColor (Color foreground, Color background)
 	}
 
 
+	#endregion
+
+	#region Mouse and Keyboard
+
+	/// <summary>
+	/// Event fired after a key has been pressed and released.
+	/// </summary>
+	public event EventHandler<KeyEventEventArgs> KeyPressed;
+
+	/// <summary>
+	/// Called after a key has been pressed and released. Fires the <see cref="KeyPressed"/> event.
+	/// </summary>
+	/// <param name="a"></param>
+	public void OnKeyPressed (KeyEventEventArgs a) => KeyPressed?.Invoke(this, a);
+
+	/// <summary>
+	/// Event fired when a key is released.
+	/// </summary>
+	public event EventHandler<KeyEventEventArgs> KeyUp;
+
+	/// <summary>
+	/// Called when a key is released. Fires the <see cref="KeyUp"/> event.
+	/// </summary>
+	/// <param name="a"></param>
+	public void OnKeyUp (KeyEventEventArgs a) => KeyUp?.Invoke (this, a);
+
+	/// <summary>
+	/// Event fired when a key is pressed.
+	/// </summary>
+	public event EventHandler<KeyEventEventArgs> KeyDown;
+
+	/// <summary>
+	/// Called when a key is pressed. Fires the <see cref="KeyDown"/> event.
+	/// </summary>
+	/// <param name="a"></param>
+	public void OnKeyDown (KeyEventEventArgs a) => KeyDown?.Invoke (this, a);
+
+	/// <summary>
+	/// Event fired when a mouse event occurs.
+	/// </summary>
+	public event EventHandler<MouseEventEventArgs> MouseEvent;
+
+	/// <summary>
+	/// Called when a mouse event occurs. Fires the <see cref="MouseEvent"/> event.
+	/// </summary>
+	/// <param name="a"></param>
+	public void OnMouseEvent (MouseEventEventArgs a) => MouseEvent?.Invoke (this, a);
+
+	/// <summary>
+	/// Simulates a key press.
+	/// </summary>
+	/// <param name="keyChar">The key character.</param>
+	/// <param name="key">The key.</param>
+	/// <param name="shift">If <see langword="true"/> simulates the Shift key being pressed.</param>
+	/// <param name="alt">If <see langword="true"/> simulates the Alt key being pressed.</param>
+	/// <param name="ctrl">If <see langword="true"/> simulates the Ctrl key being pressed.</param>
+	public abstract void SendKeys (char keyChar, ConsoleKey key, bool shift, bool alt, bool ctrl);
+
 	#endregion
 
 	/// <summary>
@@ -479,16 +532,6 @@ public enum DiagnosticFlags : uint {
 	/// <remarks>This is only implemented in <see cref="CursesDriver"/>.</remarks>
 	public abstract void Suspend ();
 
-	/// <summary>
-	/// Simulates a key press.
-	/// </summary>
-	/// <param name="keyChar">The key character.</param>
-	/// <param name="key">The key.</param>
-	/// <param name="shift">If <see langword="true"/> simulates the Shift key being pressed.</param>
-	/// <param name="alt">If <see langword="true"/> simulates the Alt key being pressed.</param>
-	/// <param name="ctrl">If <see langword="true"/> simulates the Ctrl key being pressed.</param>
-	public abstract void SendKeys (char keyChar, ConsoleKey key, bool shift, bool alt, bool ctrl);
-
 	// TODO: Move FillRect to ./Drawing	
 	/// <summary>
 	/// Fills the specified rectangle with the specified rune.
@@ -513,11 +556,6 @@ public void FillRect (Rect rect, Rune rune = default)
 	/// <param name="c"></param>
 	public void FillRect (Rect rect, char c) => FillRect (rect, new Rune (c));
 
-	/// <summary>
-	/// Ends the execution of the console driver.
-	/// </summary>
-	public abstract void End ();
-
 	/// <summary>
 	/// Returns the name of the driver and relevant library version information.
 	/// </summary>