LogitechKeyboardManager.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace LgBackLight {
	public class LogitechKeyboardManager {
		private const int VENDOR_ID = 0x046D;

		private static DeviceEventNotifier deviceEventNotifier;
		private static List<LogitechKeyboard> devices;

		public static event EventHandler<LogitechKeyboardEventArgs> KeyboardConnected;
		public static event EventHandler<LogitechKeyboardEventArgs> KeyboardDisconnected;

		private static LogitechKeyboardType[] KeyboardsToListenFor;

		public static void Init(IntPtr windowHandle, params LogitechKeyboardType[] keyboardsToListenFor) {
			KeyboardsToListenFor = keyboardsToListenFor;

			// Initialize device event dispatcher.
			Guid hidClassGuid;
			Hid.HidD_GetHidGuid(out hidClassGuid);
			deviceEventNotifier = new DeviceEventNotifier(windowHandle, hidClassGuid);
			// Register for device removal/arrival events so we can keep
			// track of the currently attached devices of interest.
			deviceEventNotifier.DeviceArrival += DeviceAdded;
			deviceEventNotifier.DeviceRemoval += DeviceRemoved;

			devices = new List<LogitechKeyboard>();

			// Open all devices we can find for now.
			var devs = HidDevice.Open(VENDOR_ID, keyboardsToListenFor.Select(d => d.ProductID));

			foreach (var dev in devs) {
				devices.Add(new LogitechKeyboard(dev, keyboardsToListenFor.Where(k => k.ProductID == dev.ProductId).First()));
			}
		}

		private static void DeviceAdded(object sender, DeviceEventArgs args) {
			HidDevice hidDevice = HidDevice.Open(args.DevicePath);
			// We can be sure a hid device was be returned,
			// since we only registered device notifications
			// for hid devices.
			if (VENDOR_ID == hidDevice.VendorId && KeyboardsToListenFor.Any(d => d.ProductID == hidDevice.ProductId)) {
				// The device added appears to be a backlight device.
				LogitechKeyboard keyboard = new LogitechKeyboard(hidDevice, KeyboardsToListenFor.Where(k => k.ProductID == hidDevice.ProductId).First());
				devices.Add(keyboard);
				if (KeyboardConnected != null)
					KeyboardConnected(null, new LogitechKeyboardEventArgs(keyboard));
			}
			else {
				// Not a backlight device, dispose!
				hidDevice.Dispose();
			}
		}

		private static void DeviceRemoved(object sender, DeviceEventArgs args) {
			// If a device was removed which exists in our dictionary,
			// then this is the time to dispose and remove it.
			string path = args.DevicePath.ToUpper();
			if (devices.Any(d => d.Device.DevicePath.ToUpper().Equals(path))) {
				var device = devices.First(d => d.Device.DevicePath.ToUpper().Equals(path));
				device.Device.Dispose();
				devices.Remove(device);
				if (KeyboardDisconnected != null)
					KeyboardDisconnected(null, new LogitechKeyboardEventArgs(device));
			}
		}

		public static List<LogitechKeyboard> GetKeyboards(LogitechKeyboardType keyboardType) {
			AssertInitialized();

			return devices.Where(
				d => d.KeyboardType.ProductID == keyboardType.ProductID &&
				d.KeyboardType.ReportID == keyboardType.ReportID
		   ).ToList();
		}

		private static void AssertInitialized() {
			if (deviceEventNotifier == null) {
				throw new ApplicationException(
						"You must first call Initialize to use the BackLight features.");
			}
		}
	}

	public class LogitechKeyboardEventArgs : EventArgs {
		public LogitechKeyboard Keyboard { get; private set; }

		public LogitechKeyboardEventArgs(LogitechKeyboard keyboard) {
			Keyboard = keyboard;
		}
	}
}