按键会生成一个硬件事件，向 Windows 操作系统报告“扫描代码”。然后根据扫描码以及其他键盘状态因素（Caps Lock 状态、Shift/Alt/Ctrl 键状态，以及任何挂起的死键击键）。转换后的 VK 值是 KeyDown 事件等报告的值。
从扫描码到 VK 码的转换取决于当前的输入语言环境 - 简单地说，输入语言环境定义了扫描码和虚拟键码之间的映射。有关键盘输入的完整说明，请参阅the MSDN documentation。
通过逆向这个查找过程，可以确定每个虚拟键码对应的扫描码（当然，同一个扫描码会因为shift/ctrl/alt状态等原因映射到多个VK码）。 Win32 API 通过使用MAPVK_VK_TO_VSC_EX 选项提供MapVirtualKeyEx 函数来执行此映射。您可以使用它来确定哪个扫描代码生成特定的 VK 代码。
不幸的是，这是您可以通过编程实现的 - 无法确定键盘的物理布局或每个扫描码的按键位置。但是，大多数物理键盘的接线方式相同，因此（例如）在大多数物理键盘设计上，左上键将具有相同的扫描码。您可以根据基本的物理键盘布局（101 键、102 键等），使用此假定约定来推断与扫描码对应的物理位置。不能保证，但这是一个相当安全的猜测。
以下代码摘自我编写的一个更大的键盘处理库（我一直打算将其开源，但没有时间）。该方法初始化一个数组 (this._virtualKeyScanCodes)，该数组由给定输入语言环境的 VK 代码索引（存储在声明为 System.Windows.Forms.InputLanguage 的 this._inputLanguage 中。您可以使用该数组来确定对应于VK 代码通过检查例如this._virtualKeyScanCodes[VK_NUMPAD0] - 如果扫描代码为零，则该 VK 在当前输入语言环境中的键盘上不可用；如果它不为零，则它是扫描代码，您可以从中推断物理键。
不幸的是，当您进入死键领域（例如，产生重音字符的多个组合键）时，事情会比这稍微复杂一些。这一切现在都太复杂了，但是如果你想进一步探索的话，Michael S. Kaplan 写了一个详细的系列blog posts。祝你好运！
private void Initialize()
{
this._virtualKeyScanCodes = new uint[MaxVirtualKeys];
// Scroll through the Scan Code (SC) values and get the Virtual Key (VK)
// values in it. Then, store the SC in each valid VK so it can act as both a
// flag that the VK is valid, and it can store the SC value.
for (uint scanCode = 0x01; scanCode <= 0xff; scanCode++)
{
uint virtualKeyCode = NativeMethods.MapVirtualKeyEx(
scanCode,
NativeMethods.MAPVK_VSC_TO_VK,
this._inputLanguage.Handle);
if (virtualKeyCode != 0)
{
this._virtualKeyScanCodes[virtualKeyCode] = scanCode;
}
}
// Add the special keys that do not get added from the code above
for (KeysEx ke = KeysEx.VK_NUMPAD0; ke <= KeysEx.VK_NUMPAD9; ke++)
{
this._virtualKeyScanCodes[(uint)ke] = NativeMethods.MapVirtualKeyEx(
(uint)ke,
NativeMethods.MAPVK_VK_TO_VSC,
this._inputLanguage.Handle);
}
this._virtualKeyScanCodes[(uint)KeysEx.VK_DECIMAL] =
NativeMethods.MapVirtualKeyEx(
(uint)KeysEx.VK_DECIMAL, NativeMethods.MAPVK_VK_TO_VSC, this._inputLanguage.Handle);
this._virtualKeyScanCodes[(uint)KeysEx.VK_DIVIDE] =
NativeMethods.MapVirtualKeyEx(
(uint)KeysEx.VK_DIVIDE, NativeMethods.MAPVK_VK_TO_VSC, this._inputLanguage.Handle);
this._virtualKeyScanCodes[(uint)KeysEx.VK_CANCEL] =
NativeMethods.MapVirtualKeyEx(
(uint)KeysEx.VK_CANCEL, NativeMethods.MAPVK_VK_TO_VSC, this._inputLanguage.Handle);
this._virtualKeyScanCodes[(uint)KeysEx.VK_LSHIFT] =
NativeMethods.MapVirtualKeyEx(
(uint)KeysEx.VK_LSHIFT, NativeMethods.MAPVK_VK_TO_VSC, this._inputLanguage.Handle);
this._virtualKeyScanCodes[(uint)KeysEx.VK_RSHIFT] =
NativeMethods.MapVirtualKeyEx(
(uint)KeysEx.VK_RSHIFT, NativeMethods.MAPVK_VK_TO_VSC, this._inputLanguage.Handle);
this._virtualKeyScanCodes[(uint)KeysEx.VK_LCONTROL] =
NativeMethods.MapVirtualKeyEx(
(uint)KeysEx.VK_LCONTROL, NativeMethods.MAPVK_VK_TO_VSC, this._inputLanguage.Handle);
this._virtualKeyScanCodes[(uint)KeysEx.VK_RCONTROL] =
NativeMethods.MapVirtualKeyEx(
(uint)KeysEx.VK_RCONTROL, NativeMethods.MAPVK_VK_TO_VSC, this._inputLanguage.Handle);
this._virtualKeyScanCodes[(uint)KeysEx.VK_LMENU] =
NativeMethods.MapVirtualKeyEx(
(uint)KeysEx.VK_LMENU, NativeMethods.MAPVK_VK_TO_VSC, this._inputLanguage.Handle);
this._virtualKeyScanCodes[(uint)KeysEx.VK_RMENU] =
NativeMethods.MapVirtualKeyEx(
(uint)KeysEx.VK_RMENU, NativeMethods.MAPVK_VK_TO_VSC, this._inputLanguage.Handle);
this._virtualKeyScanCodes[(uint)KeysEx.VK_LWIN] =
NativeMethods.MapVirtualKeyEx(
(uint)KeysEx.VK_LWIN, NativeMethods.MAPVK_VK_TO_VSC, this._inputLanguage.Handle);
this._virtualKeyScanCodes[(uint)KeysEx.VK_RWIN] =
NativeMethods.MapVirtualKeyEx(
(uint)KeysEx.VK_RWIN, NativeMethods.MAPVK_VK_TO_VSC, this._inputLanguage.Handle);
this._virtualKeyScanCodes[(uint)KeysEx.VK_PAUSE] =
NativeMethods.MapVirtualKeyEx(
(uint)KeysEx.VK_PAUSE, NativeMethods.MAPVK_VK_TO_VSC_EX, this._inputLanguage.Handle);
this._virtualKeyScanCodes[(uint)KeysEx.VK_VOLUME_UP] =
NativeMethods.MapVirtualKeyEx(
(uint)KeysEx.VK_VOLUME_UP, NativeMethods.MAPVK_VK_TO_VSC_EX, this._inputLanguage.Handle);
this._virtualKeyScanCodes[(uint)KeysEx.VK_VOLUME_DOWN] =
NativeMethods.MapVirtualKeyEx(
(uint)KeysEx.VK_VOLUME_DOWN, NativeMethods.MAPVK_VK_TO_VSC_EX, this._inputLanguage.Handle);
this._virtualKeyScanCodes[(uint)KeysEx.VK_VOLUME_MUTE] =
NativeMethods.MapVirtualKeyEx(
(uint)KeysEx.VK_VOLUME_MUTE, NativeMethods.MAPVK_VK_TO_VSC_EX, this._inputLanguage.Handle);
this._virtualKeyScanCodes[(uint)KeysEx.VK_MEDIA_NEXT_TRACK] =
NativeMethods.MapVirtualKeyEx(
(uint)KeysEx.VK_MEDIA_NEXT_TRACK, NativeMethods.MAPVK_VK_TO_VSC_EX, this._inputLanguage.Handle);
this._virtualKeyScanCodes[(uint)KeysEx.VK_MEDIA_PREV_TRACK] =
NativeMethods.MapVirtualKeyEx(
(uint)KeysEx.VK_MEDIA_PREV_TRACK, NativeMethods.MAPVK_VK_TO_VSC_EX, this._inputLanguage.Handle);
this._virtualKeyScanCodes[(uint)KeysEx.VK_MEDIA_PLAY_PAUSE] =
NativeMethods.MapVirtualKeyEx(
(uint)KeysEx.VK_MEDIA_PLAY_PAUSE, NativeMethods.MAPVK_VK_TO_VSC_EX, this._inputLanguage.Handle);
this._virtualKeyScanCodes[(uint)KeysEx.VK_MEDIA_STOP] =
NativeMethods.MapVirtualKeyEx(
(uint)KeysEx.VK_MEDIA_STOP, NativeMethods.MAPVK_VK_TO_VSC_EX, this._inputLanguage.Handle);
this._stateController = new KeyboardStateController();
this._baseVirtualKeyTable = new VirtualKeyTable(this);
}
编辑：另见this question，与您的类似。