(unfinished) Helper to convert WinRT Virtual Keys to ASCII

VirtualKeyHelper.cs

using System.Diagnostics;
using Windows.System;

namespace Toolbox.WinRT
{
	enum VKeyClass
	{
		Control, // 0-31, 33-47, 91-95, 144-165
		Character, // 32, 48-90
		NumPad, // 96-111
		Function // 112 - 135
	}

	public enum VKeyCharacterClass
	{
		Space,
		Numeric,
		Alphabetic
	}

	static class VirtualKeyHelper
	{
		public static char? tryConvertKeyToCharacter(VirtualKey key, ModifierKeys modifiers)
		{
			if (modifiers != ModifierKeys.Shift && modifiers != ModifierKeys.None)
				return null;

			var classification = tryClassify(key);
			if (classification == null || classification.Value != VKeyClass.Character)
				return null;

			var k = (int)key;
			// don't handle the numeric key pad right now.
			if (k >= 96)
				return null;

			bool shift = modifiers == ModifierKeys.Shift;

			var charClass = tryClassifyCharacterKey(key);
			if (charClass == null)
				return null;
			switch (charClass.Value)
			{
				case VKeyCharacterClass.Alphabetic:
					return (char)(shift ? k : k + ('a' - 'A'));

				case VKeyCharacterClass.Space:
				case VKeyCharacterClass.Numeric:
					return (char)k;
			}
			return null;
		}

		public static VKeyClass? tryClassify(VirtualKey key)
		{
			var k = (int)key;
			if (k >= 112 && k <= 135)
				return VKeyClass.Function;
			if (k == 32 || k >= 48 && k <= 57 || k >= 65 && k <= 90)
				return VKeyClass.Character;
			if (k >= 96 && k <= 111)
				return VKeyClass.NumPad;
			if (k >= 0 && k <= 31 || k >= 33 && k <= 47 || k >= 91 && k <= 95 || k >= 144 && k <= 165)
				return VKeyClass.Control;

			return null;
		}

		public static VKeyCharacterClass? tryClassifyCharacterKey(VirtualKey key)
		{
			Debug.Assert(tryClassify(key) == VKeyClass.Character);
			var k = (int)key;
			if (k == 32)
				return VKeyCharacterClass.Space;
			if (k >= 48 && k <= 57)
				return VKeyCharacterClass.Numeric;
			if (k >= 65 && k <= 90)
				return VKeyCharacterClass.Alphabetic;
			return null;
		}
	}
}