KeyEventArgs.Key 到字符 [英] KeyEventArgs.Key to char

问题描述

有什么办法可以把WPF的KeyEventArgs.Key转成Char?

Is there any way to convert WPF's KeyEventArgs.Key to Char?

我尝试使用 KeyInterop:

var x = (Char)KeyInterop.VirtualKeyFromKey(e.Key);

对于数字和字母它可以正常工作，但对于其他字符则不行.例如.对于 OemComma，它返回 '1/4' 而不是 ','.

For numbers and letters it works fine, but for other characters it doesn't. E.g. for OemComma it returns '1/4' instead of ','.

我需要它来防止用户在 TextBox 中输入除数字和分隔符(即逗号或句点)以外的任何字符.

I need it to prevent user of inputting into TextBox any characters except numbers and separators (i.e. commas or periods).

推荐答案

UPDATE:下面的评论找到了原http://stackoverflow.com/a/5826175/187650

UPDATE: the comment below found the original http://stackoverflow.com/a/5826175/187650

在我忘记的地方找到了这个.仍在使用它，不确定它有什么漏洞，但据我所知，它确实有效.

Found this somewhere that I've forgotten. Still using it, not sure what holes it has, but it's worked as far as I know.

public static class KeyEventUtility
{
    // ReSharper disable InconsistentNaming
    public enum MapType : uint
    {
        MAPVK_VK_TO_VSC = 0x0,
        MAPVK_VSC_TO_VK = 0x1,
        MAPVK_VK_TO_CHAR = 0x2,
        MAPVK_VSC_TO_VK_EX = 0x3,
    }
    // ReSharper restore InconsistentNaming

    [DllImport( "user32.dll" )]
    public static extern int ToUnicode(
        uint wVirtKey,
        uint wScanCode,
        byte[] lpKeyState,
        [Out, MarshalAs( UnmanagedType.LPWStr, SizeParamIndex = 4 )] 
        StringBuilder pwszBuff,
        int cchBuff,
        uint wFlags );

    [DllImport( "user32.dll" )]
    public static extern bool GetKeyboardState( byte[] lpKeyState );

    [DllImport( "user32.dll" )]
    public static extern uint MapVirtualKey( uint uCode, MapType uMapType );

    public static char GetCharFromKey( Key key )
    {
        char ch = ' ';

        int virtualKey = KeyInterop.VirtualKeyFromKey( key );
        var keyboardState = new byte[256];
        GetKeyboardState( keyboardState );

        uint scanCode = MapVirtualKey( (uint)virtualKey, MapType.MAPVK_VK_TO_VSC );
        var stringBuilder = new StringBuilder( 2 );

        int result = ToUnicode( (uint)virtualKey, scanCode, keyboardState, stringBuilder, stringBuilder.Capacity, 0 );
        switch ( result )
        {
        case -1:
            break;
        case 0:
            break;
        case 1:
            {
                ch = stringBuilder[0];
                break;
            }
        default:
            {
                ch = stringBuilder[0];
                break;
            }
        }
        return ch;
    }
}

这篇关于KeyEventArgs.Key 到字符的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！