improve gamepad init and support hotplugging

src/Game.cs

@@ -205,6 +205,14 @@ namespace MoonWorks
 					case SDL.SDL_EventType.SDL_DROPFILE:
 						HandleFileDrop(_event);
 						break;
+
+					case SDL.SDL_EventType.SDL_CONTROLLERDEVICEADDED:
+						HandleControllerAdded(_event);
+						break;
+
+					case SDL.SDL_EventType.SDL_CONTROLLERDEVICEREMOVED:
+						HandleControllerRemoved(_event);
+						break;
 				}
 			}
 		}
@@ -244,6 +252,22 @@ namespace MoonWorks
 			DropFile(filePath);
 		}
 
+		private void HandleControllerAdded(SDL.SDL_Event evt)
+		{
+			var index = evt.cdevice.which;
+			if (SDL.SDL_IsGameController(index) == SDL.SDL_bool.SDL_TRUE)
+			{
+				System.Console.WriteLine($"New controller detected!");
+				Inputs.AddGamepad(index);
+			}
+		}
+
+		private void HandleControllerRemoved(SDL.SDL_Event evt)
+		{
+			System.Console.WriteLine($"Controller removal detected!");
+			Inputs.RemoveGamepad(evt.cdevice.which);
+		}
+
 		private TimeSpan AdvanceElapsedTime()
 		{
 			long currentTicks = gameTimer.Elapsed.Ticks;

src/Input/Axis.cs

@@ -1,4 +1,3 @@
-using System;
 using MoonWorks.Math;
 using SDL2;
 
@@ -6,7 +5,7 @@ namespace MoonWorks.Input
 {
 	public class Axis
 	{
-		IntPtr GamepadHandle;
+		public Gamepad Parent { get; }
 		SDL.SDL_GameControllerAxis SDL_Axis;
 
 		public AxisCode Code { get; private set; }
@@ -17,11 +16,11 @@ namespace MoonWorks.Input
 		public float Value { get; private set; }
 
 		public Axis(
-			IntPtr gamepadHandle,
+			Gamepad parent,
 			AxisCode code,
 			SDL.SDL_GameControllerAxis sdlAxis
 		) {
-			GamepadHandle = gamepadHandle;
+			Parent = parent;
 			SDL_Axis = sdlAxis;
 			Code = code;
 		}
@@ -29,7 +28,7 @@ namespace MoonWorks.Input
 		internal void Update()
 		{
 			Value = MathHelper.Normalize(
-				SDL.SDL_GameControllerGetAxis(GamepadHandle, SDL_Axis),
+				SDL.SDL_GameControllerGetAxis(Parent.Handle, SDL_Axis),
 				short.MinValue, short.MaxValue,
 				-1, 1
 			);

src/Input/Gamepad.cs

@@ -8,7 +8,9 @@ namespace MoonWorks.Input
 	public class Gamepad
 	{
 		internal IntPtr Handle;
-		internal int Index;
+		internal int JoystickInstanceID;
+
+		public int Slot { get; internal set; }
 
 		public GamepadButton A { get; }
 		public GamepadButton B { get; }
@@ -61,37 +63,40 @@ namespace MoonWorks.Input
 
 		private VirtualButton[] VirtualButtons;
 
-		internal Gamepad(IntPtr handle, int index)
+		internal Gamepad(IntPtr handle, int slot)
 		{
 			Handle = handle;
-			Index = index;
+			Slot = slot;
+
+			IntPtr joystickHandle = SDL.SDL_GameControllerGetJoystick(Handle);
+			JoystickInstanceID = SDL.SDL_JoystickInstanceID(joystickHandle);
 
 			AnyPressed = false;
 
-			A = new GamepadButton(handle, GamepadButtonCode.A, SDL.SDL_GameControllerButton.SDL_CONTROLLER_BUTTON_A);
+			A = new GamepadButton(this, GamepadButtonCode.A, SDL.SDL_GameControllerButton.SDL_CONTROLLER_BUTTON_A);
-			B = new GamepadButton(handle, GamepadButtonCode.B, SDL.SDL_GameControllerButton.SDL_CONTROLLER_BUTTON_B);
+			B = new GamepadButton(this, GamepadButtonCode.B, SDL.SDL_GameControllerButton.SDL_CONTROLLER_BUTTON_B);
-			X = new GamepadButton(handle, GamepadButtonCode.X, SDL.SDL_GameControllerButton.SDL_CONTROLLER_BUTTON_X);
+			X = new GamepadButton(this, GamepadButtonCode.X, SDL.SDL_GameControllerButton.SDL_CONTROLLER_BUTTON_X);
-			Y = new GamepadButton(handle, GamepadButtonCode.Y, SDL.SDL_GameControllerButton.SDL_CONTROLLER_BUTTON_Y);
+			Y = new GamepadButton(this, GamepadButtonCode.Y, SDL.SDL_GameControllerButton.SDL_CONTROLLER_BUTTON_Y);
 
-			Back = new GamepadButton(handle, GamepadButtonCode.Back, SDL.SDL_GameControllerButton.SDL_CONTROLLER_BUTTON_BACK);
+			Back = new GamepadButton(this, GamepadButtonCode.Back, SDL.SDL_GameControllerButton.SDL_CONTROLLER_BUTTON_BACK);
-			Guide = new GamepadButton(handle, GamepadButtonCode.Guide, SDL.SDL_GameControllerButton.SDL_CONTROLLER_BUTTON_GUIDE);
+			Guide = new GamepadButton(this, GamepadButtonCode.Guide, SDL.SDL_GameControllerButton.SDL_CONTROLLER_BUTTON_GUIDE);
-			Start = new GamepadButton(handle, GamepadButtonCode.Start, SDL.SDL_GameControllerButton.SDL_CONTROLLER_BUTTON_START);
+			Start = new GamepadButton(this, GamepadButtonCode.Start, SDL.SDL_GameControllerButton.SDL_CONTROLLER_BUTTON_START);
 
-			LeftStick = new GamepadButton(handle, GamepadButtonCode.LeftStick, SDL.SDL_GameControllerButton.SDL_CONTROLLER_BUTTON_LEFTSTICK);
+			LeftStick = new GamepadButton(this, GamepadButtonCode.LeftStick, SDL.SDL_GameControllerButton.SDL_CONTROLLER_BUTTON_LEFTSTICK);
-			RightStick = new GamepadButton(handle, GamepadButtonCode.RightStick, SDL.SDL_GameControllerButton.SDL_CONTROLLER_BUTTON_RIGHTSTICK);
+			RightStick = new GamepadButton(this, GamepadButtonCode.RightStick, SDL.SDL_GameControllerButton.SDL_CONTROLLER_BUTTON_RIGHTSTICK);
 
-			LeftShoulder = new GamepadButton(handle, GamepadButtonCode.LeftShoulder, SDL.SDL_GameControllerButton.SDL_CONTROLLER_BUTTON_LEFTSHOULDER);
+			LeftShoulder = new GamepadButton(this, GamepadButtonCode.LeftShoulder, SDL.SDL_GameControllerButton.SDL_CONTROLLER_BUTTON_LEFTSHOULDER);
-			RightShoulder = new GamepadButton(handle, GamepadButtonCode.RightShoulder, SDL.SDL_GameControllerButton.SDL_CONTROLLER_BUTTON_RIGHTSHOULDER);
+			RightShoulder = new GamepadButton(this, GamepadButtonCode.RightShoulder, SDL.SDL_GameControllerButton.SDL_CONTROLLER_BUTTON_RIGHTSHOULDER);
 
-			DpadUp = new GamepadButton(handle, GamepadButtonCode.DpadUp, SDL.SDL_GameControllerButton.SDL_CONTROLLER_BUTTON_DPAD_UP);
+			DpadUp = new GamepadButton(this, GamepadButtonCode.DpadUp, SDL.SDL_GameControllerButton.SDL_CONTROLLER_BUTTON_DPAD_UP);
-			DpadDown = new GamepadButton(handle, GamepadButtonCode.DpadDown, SDL.SDL_GameControllerButton.SDL_CONTROLLER_BUTTON_DPAD_DOWN);
+			DpadDown = new GamepadButton(this, GamepadButtonCode.DpadDown, SDL.SDL_GameControllerButton.SDL_CONTROLLER_BUTTON_DPAD_DOWN);
-			DpadLeft = new GamepadButton(handle, GamepadButtonCode.DpadLeft, SDL.SDL_GameControllerButton.SDL_CONTROLLER_BUTTON_DPAD_LEFT);
+			DpadLeft = new GamepadButton(this, GamepadButtonCode.DpadLeft, SDL.SDL_GameControllerButton.SDL_CONTROLLER_BUTTON_DPAD_LEFT);
-			DpadRight = new GamepadButton(handle, GamepadButtonCode.DpadRight, SDL.SDL_GameControllerButton.SDL_CONTROLLER_BUTTON_DPAD_RIGHT);
+			DpadRight = new GamepadButton(this, GamepadButtonCode.DpadRight, SDL.SDL_GameControllerButton.SDL_CONTROLLER_BUTTON_DPAD_RIGHT);
 
-			LeftX = new Axis(handle, AxisCode.LeftX, SDL.SDL_GameControllerAxis.SDL_CONTROLLER_AXIS_LEFTX);
+			LeftX = new Axis(this, AxisCode.LeftX, SDL.SDL_GameControllerAxis.SDL_CONTROLLER_AXIS_LEFTX);
-			LeftY = new Axis(handle, AxisCode.LeftY, SDL.SDL_GameControllerAxis.SDL_CONTROLLER_AXIS_LEFTY);
+			LeftY = new Axis(this, AxisCode.LeftY, SDL.SDL_GameControllerAxis.SDL_CONTROLLER_AXIS_LEFTY);
-			RightX = new Axis(handle, AxisCode.RightX, SDL.SDL_GameControllerAxis.SDL_CONTROLLER_AXIS_RIGHTX);
+			RightX = new Axis(this, AxisCode.RightX, SDL.SDL_GameControllerAxis.SDL_CONTROLLER_AXIS_RIGHTX);
-			RightY = new Axis(handle, AxisCode.RightY, SDL.SDL_GameControllerAxis.SDL_CONTROLLER_AXIS_RIGHTY);
+			RightY = new Axis(this, AxisCode.RightY, SDL.SDL_GameControllerAxis.SDL_CONTROLLER_AXIS_RIGHTY);
 
 			LeftXLeft = new AxisButton(LeftX, false);
 			LeftXRight = new AxisButton(LeftX, true);
@@ -103,8 +108,8 @@ namespace MoonWorks.Input
 			RightYUp = new AxisButton(RightY, false);
 			RightYDown = new AxisButton(RightY, true);
 
-			TriggerLeft = new Trigger(handle, TriggerCode.Left, SDL.SDL_GameControllerAxis.SDL_CONTROLLER_AXIS_TRIGGERLEFT);
+			TriggerLeft = new Trigger(this, TriggerCode.Left, SDL.SDL_GameControllerAxis.SDL_CONTROLLER_AXIS_TRIGGERLEFT);
-			TriggerRight = new Trigger(handle, TriggerCode.Right, SDL.SDL_GameControllerAxis.SDL_CONTROLLER_AXIS_TRIGGERRIGHT);
+			TriggerRight = new Trigger(this, TriggerCode.Right, SDL.SDL_GameControllerAxis.SDL_CONTROLLER_AXIS_TRIGGERRIGHT);
 
 			TriggerLeftButton = new TriggerButton(TriggerLeft);
 			TriggerRightButton = new TriggerButton(TriggerRight);

src/Input/Input.cs

@@ -24,16 +24,10 @@ namespace MoonWorks.Input
 
 			gamepads = new Gamepad[MAX_GAMEPADS];
 
-			for (var i = 0; i < 4; i += 1)
+			// initialize dummy controllers
+			for (var slot = 0; slot < MAX_GAMEPADS; slot += 1)
 			{
-				if (SDL.SDL_IsGameController(i) == SDL.SDL_bool.SDL_TRUE)
+				gamepads[slot] = new Gamepad(IntPtr.Zero, slot);
-				{
-					gamepads[i] = new Gamepad(SDL.SDL_GameControllerOpen(i), i);
-				}
-				else
-				{
-					gamepads[i] = new Gamepad(IntPtr.Zero, -1);
-				}
 			}
 		}
 
@@ -74,14 +68,49 @@ namespace MoonWorks.Input
 
 		public bool GamepadExists(int slot)
 		{
+			if (slot < 0 || slot >= MAX_GAMEPADS)
+			{
+				return false;
+			}
+
 			return !gamepads[slot].IsDummy;
 		}
 
+		// From 0-4
 		public Gamepad GetGamepad(int slot)
 		{
 			return gamepads[slot];
 		}
 
+		internal void AddGamepad(int index)
+		{
+			for (var slot = 0; slot < MAX_GAMEPADS; slot += 1)
+			{
+				if (!GamepadExists(slot))
+				{
+					gamepads[slot].Handle = SDL.SDL_GameControllerOpen(index);
+					System.Console.WriteLine($"Gamepad added to slot {slot}!");
+					return;
+				}
+			}
+
+			System.Console.WriteLine("Too many gamepads already!");
+		}
+
+		internal void RemoveGamepad(int joystickInstanceID)
+		{
+			for (int slot = 0; slot < MAX_GAMEPADS; slot += 1)
+			{
+				if (joystickInstanceID == gamepads[slot].JoystickInstanceID)
+				{
+					SDL.SDL_GameControllerClose(gamepads[slot].Handle);
+					gamepads[slot].Handle = IntPtr.Zero;
+					System.Console.WriteLine($"Removing gamepad from slot {slot}!");
+					return;
+				}
+			}
+		}
+
 		internal static void OnTextInput(char c)
 		{
 			if (TextInput != null)

src/Input/Trigger.cs

@@ -1,4 +1,3 @@
-using System;
 using MoonWorks.Math;
 using SDL2;
 
@@ -6,7 +5,7 @@ namespace MoonWorks.Input
 {
 	public class Trigger
 	{
-		public IntPtr GamepadHandle;
+		public Gamepad Parent { get; }
 		public SDL.SDL_GameControllerAxis SDL_Axis;
 
 		public TriggerCode Code { get; }
@@ -17,11 +16,11 @@ namespace MoonWorks.Input
 		public float Value { get; private set; }
 
 		public Trigger(
-			IntPtr gamepadHandle,
+			Gamepad parent,
 			TriggerCode code,
 			SDL.SDL_GameControllerAxis sdlAxis
 		) {
-			GamepadHandle = gamepadHandle;
+			Parent = parent;
 			Code = code;
 			SDL_Axis = sdlAxis;
 		}
@@ -29,7 +28,7 @@ namespace MoonWorks.Input
 		internal void Update()
 		{
 			Value = MathHelper.Normalize(
-				SDL.SDL_GameControllerGetAxis(GamepadHandle, SDL_Axis),
+				SDL.SDL_GameControllerGetAxis(Parent.Handle, SDL_Axis),
 				0, short.MaxValue,
 				0, 1
 			);

src/Input/VirtualButtons/GamepadButton.cs

@@ -1,25 +1,23 @@
-using System;
 using SDL2;
 
 namespace MoonWorks.Input
 {
 	public class GamepadButton : VirtualButton
 	{
-		IntPtr GamepadHandle;
+		public Gamepad Parent { get; }
 		SDL.SDL_GameControllerButton SDL_Button;
+		public GamepadButtonCode Code { get; }
 
-		public GamepadButtonCode Code { get; private set; }
+		internal GamepadButton(Gamepad parent, GamepadButtonCode code, SDL.SDL_GameControllerButton sdlButton)
-
-		internal GamepadButton(IntPtr gamepadHandle, GamepadButtonCode code, SDL.SDL_GameControllerButton sdlButton)
 		{
-			GamepadHandle = gamepadHandle;
+			Parent = parent;
 			Code = code;
 			SDL_Button = sdlButton;
 		}
 
 		internal override bool CheckPressed()
 		{
-			return MoonWorks.Conversions.ByteToBool(SDL.SDL_GameControllerGetButton(GamepadHandle, SDL_Button));
+			return MoonWorks.Conversions.ByteToBool(SDL.SDL_GameControllerGetButton(Parent.Handle, SDL_Button));
 		}
 	}
 }