[Platform] Implemented legacy IJoystickDriver

LegacyJoystickDriver implements the legacy IJoystickDriver interface
(GameWindow.Joysticks) in terms of the new IJoystickDriver2 interface
(OpenTK.Input.Joystick).

This removes a large chunk of code from each platform backend, as they
no longer need to implement IJoystickDriver themselves. Additionally,
it adds support for device hot plugging which was previously missing.

Source/OpenTK/OpenTK.csproj

@@ -798,6 +798,7 @@
     <Compile Include="Input\ConfigurationType.cs" />
     <Compile Include="Input\GamePadConfigurationSource.cs" />
     <Compile Include="Input\GamePadConfigurationItem.cs" />
+    <Compile Include="Platform\LegacyJoystickDriver.cs" />
   </ItemGroup>
   <Import Project="$(MSBuildBinPath)\Microsoft.CSharp.targets" />
   <PropertyGroup>

Source/OpenTK/Platform/LegacyJoystickDriver.cs

@@ -0,0 +1,106 @@
+#region License
+//
+// LegacyJoystickDriver.cs
+//
+// Author:
+//       Stefanos A. <stapostol@gmail.com>
+//
+// Copyright (c) 2006-2014 Stefanos Apostolopoulos
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+// THE SOFTWARE.
+//
+#endregion
+
+using System;
+using System.Collections.Generic;
+using OpenTK.Input;
+
+namespace OpenTK.Platform
+{
+    internal class LegacyJoystickDriver : IJoystickDriver
+    {
+        static readonly string ConnectedName = "Connected Joystick";
+        static readonly string DisconnectedName = "Disconnected Joystick";
+        readonly List<JoystickDevice> joysticks = new List<JoystickDevice>();
+        readonly IList<JoystickDevice> joysticks_readonly;
+
+        class LegacyJoystickDevice : JoystickDevice
+        {
+            public LegacyJoystickDevice(int id, int axes, int buttons)
+                : base(id, axes, buttons)
+            { }
+        }
+
+        internal LegacyJoystickDriver()
+        {
+            joysticks_readonly = joysticks.AsReadOnly();
+            for (int i = 0; i < 4; i++)
+            {
+                joysticks.Add(new LegacyJoystickDevice(i, 0, 0));
+                joysticks[i].Description = DisconnectedName;
+            }
+        }
+
+        public void Poll()
+        {
+            for (int i = 0; i < 4; i++)
+            {
+                JoystickCapabilities caps = Joystick.GetCapabilities(i);
+                if (caps.IsConnected && joysticks[i].Description == DisconnectedName)
+                {
+                    // New joystick connected
+                    JoystickDevice device = new LegacyJoystickDevice(i, caps.AxisCount, caps.ButtonCount);
+                    //device.Description = Joystick.GetName(i);
+                    device.Description = ConnectedName;
+                }
+                else if (!caps.IsConnected && joysticks[i].Description != DisconnectedName)
+                {
+                    // Joystick disconnected
+                    joysticks[i] = new LegacyJoystickDevice(i, 0, 0);
+                    joysticks[i].Description = DisconnectedName;
+                }
+
+                JoystickState state = Joystick.GetState(i);
+                for (int axis_index = 0; axis_index < (int)JoystickAxis.Last; axis_index++)
+                {
+                    JoystickAxis axis = JoystickAxis.Axis0 + axis_index;
+                    joysticks[i].SetAxis(axis, state.GetAxis(axis));
+                }
+                for (int button_index = 0; button_index < (int)JoystickButton.Last; button_index++)
+                {
+                    JoystickButton button = JoystickButton.Button0 + button_index;
+                    joysticks[i].SetButton(button, state.GetButton(button) == ButtonState.Pressed);
+                }
+            }
+        }
+
+        #region IJoystickDriver Members
+
+        public IList<JoystickDevice> Joysticks
+        {
+            get
+            {
+                return joysticks_readonly;
+            }
+        }
+
+        #endregion
+    }
+}
+