按下键会生成一个硬件事件，向Windows操作系统报告“扫描代码”。然后，根据扫描代码沿着其他键盘状态因素（Caps Lock状态、Shift/Alt/Ctrl键状态以及任何挂起的死键击），将此扫描代码转换为“虚拟键代码”。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区域设置-简单地说，输入区域设置定义了扫描码和虚拟按键代码之间的Map。有关键盘输入的完整说明，请参阅the MSDN documentation。
通过反转此查找过程，可以确定与每个虚拟键代码对应的扫描代码（当然，由于shift/ctrl/alt状态等原因，同一个扫描代码将Map到多个VK代码）。Win32 API提供MapVirtualKeyEx函数，通过使用MAPVK_VK_TO_VSC_EX选项来执行此Map。您可以使用此函数确定哪个扫描代码生成特定的VK代码。
不幸的是，这是你所能通过编程做到的最远--没有办法为每个扫描码确定键盘的物理布局或按键的位置，然而，大多数物理键盘的接线方式都是一样的，所以（例如）在大多数物理键盘设计上，左上角的键将具有相同的扫描码。你可以根据基本的物理键盘布局（101键，102键等），使用这个假设的约定来推断对应于扫描码的物理位置。这不能保证，但这是一个相当安全的猜测。
下面的代码摘自我编写的一个更大的键盘处理库（我一直想开源它，但是没有时间）。该方法初始化一个数组（this._virtualKeyScanCodes），由给定输入法区域设置的VK代码索引（存储在this._inputLanguage中，声明为System.Windows.Forms.InputLanguage）。您可以使用数组来确定对应于VK代码的扫描代码，例如检查this._virtualKeyScanCodes[VK_NUMPAD0]-如果扫描代码为零，则在当前输入法区域设置的键盘上该VK不可用;如果它不为零，则它是可以从中推断物理密钥的扫描码。
不幸的是，当你进入死键的领域（例如，产生重音字符的多个键组合）时，事情会稍微复杂一些。现在讨论这些太复杂了，但是Michael S. Kaplan早在2006年就写了一个详细的blog posts系列，如果你想进一步探讨这个问题的话。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：也可以看this question，它和你的类似。

没有包含键盘布局的内置.NET类。键盘布局是操作系统（通常是Windows）的一个功能。在涉及.NET时，按下的键已从硬件事件转换为软件事件。如果您想看到实际操作，找到两个键盘布局，其中一个键在它们之间移动。设置一个虚拟应用程序，该应用程序带有Key_Down事件的事件处理程序，然后注意事件参数是相同的;如果您按了-键，则无论-键位于何处，您都按了-键。