wpf KeyEventArgs.Key 到字符
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KeyEventArgs.Key to char
提问by max_hassen
Is there any way to convert WPF's KeyEventArgs.Keyto Char?
有什么方法可以将 WPF 转换KeyEventArgs.Key为Char?
I tried to use KeyInterop:
我尝试使用KeyInterop：
var x = (Char)KeyInterop.VirtualKeyFromKey(e.Key);
For numbers and letters it works fine, but for other characters it doesn't.
E.g. for OemCommait returns '1/4' instead of ','.
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，OemComma它返回 '1/4' 而不是 ','。
I need it to prevent user of inputting into TextBoxany characters except numbers and separators (i.e. commas or periods).
我需要它来防止用户输入TextBox除数字和分隔符（即逗号或句点）以外的任何字符。
回答by kenny
UPDATE: the comment below found the original http://stackoverflow.com/a/5826175/187650
更新：下面的评论找到了原来的http://stackoverflow.com/a/5826175/187650
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.
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。
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;
}
}
回答by juFo
My first suggestion would be using PreviewTextInputand using the TextCompositionEventArgs. However this 'eats' the space-characters. For this 'space'-issue see:
我的第一个建议是使用PreviewTextInput和使用TextCompositionEventArgs。然而，这“吃掉”了空格字符。对于这个“空间”问题，请参见：
- How can I prevent input controls from stealing the space character from the TextCompositionManager?
- Why does PreviewTextInput not handle spaces?
another solution would be using the KeyConverterin a KeyUpevent:
另一种解决方案是在KeyUp事件中使用KeyConverter：
KeyConverter kc = new KeyConverter();
var str = kc.ConvertToString(e.Key);
For WPF: https://msdn.microsoft.com/en-us/library/system.windows.input.keyconverter(v=vs.110).aspxFor Winforms: https://msdn.microsoft.com/en-us/library/system.windows.forms.keysconverter.aspx
对于WPF：https: //msdn.microsoft.com/en-us/library/system.windows.input.keyconverter( v = vs.110).aspx对于Winforms：https: //msdn.microsoft.com/en-我们/图书馆/system.windows.forms.keysconverter.aspx
Note that KeyConverter will give you the string "Space" instead of " ". (same for "Esc" when pressing the escape key.
请注意，KeyConverter 将为您提供字符串“Space”而不是“”。（按退出键时“Esc”相同。
Another WPF solution is using this in the KeyUpevent:
另一个 WPF 解决方案是在KeyUp事件中使用它：
((char)KeyInterop.VirtualKeyFromKey(e.Key))
回答by bash.d
Why such approach? There are different ways of preventing users from performing such input. For example, define an event-handler for the TextBox.TextChanged-event and when the input is not a decimal or a separator, revoke the input.
为什么采用这种方法？有多种方法可以防止用户执行此类输入。例如，为TextBox.TextChanged-event定义事件处理程序，当输入不是小数或分隔符时，撤销输入。
private void textChangedEventHandler(object sender, TextChangedEventArgs args){
//args contains a property `Changes` where you can see what happened
//check for invalid characters and revoke them
}
See TextChangedEventArgsand the event.
