WPF中的按键事件 [英] Key press event in WPF

问题描述

嗨..
我希望用户仅在文本框中输入数字值.
我收到了以下代码:

Hi..
I want user to enter only numeric values in textbox.
I got this code:

private void txtType1_KeyPress(object sender, KeyPressEventArgs e)
{
     int isNumber = 0;
     e.Handled = !int.TryParse(e.KeyChar.ToString(), out isNumber);
}

但我没有得到textbox_KeyPress事件.

解决方案是什么?

but i am not getting textbox_KeyPress event.

Whats the solution?

推荐答案

尝试一下.

Try this.

private void NumericTextBox_PreviewKeyDown(object sender, KeyEventArgs e)
{
    if (!Char.IsDigit((char)KeyInterop.VirtualKeyFromKey(e.Key)) & e.Key != Key.Back | e.Key == Key.Space)
    {
        e.Handled = true;
        MessageBox.Show("I only accept numbers, sorry. :(", "This textbox says...");
    }
}

您可能需要导入System.Windows.Input以获得KeyInterop

上面的代码段进入了TextBox的PreviewKeyDown事件.

You may need to import System.Windows.Input to get KeyInterop

The code segment above goes into the PreviewKeyDown event of the TextBox.

WPF中的验证应使用验证规则进行处理.
看看这篇文章.

Validations in WPF should be handled using validation rules.
Have a look at this article.

winforms中的KeyPress是刚好适合输入解析，
不幸的是，WPF没有此类事件；(
这是我用于解析文本框输入的方法，允许输入带符号的十进制数字
(代码很烂，但我找不到更简单的方法)

KeyPress in winforms was just perfect for input parsing,
unfortunately WPF don''t have such event ;(
here my metod for parsing textbox input, allowing to input signed decimal number
(code is sucks but i cant find simpler way)

private void textBox1_PreviewTextInput(object sender, TextCompositionEventArgs e)
        {
            if (!char.IsNumber(e.Text, e.Text.Length-1))
            {
                e.Handled = true;
            }

            if (( (e.Text).ToCharArray()[e.Text.Length - 1] == '.') || ((e.Text).ToCharArray()[e.Text.Length - 1] == ',')) 
            {
                e.Handled = true;
                if (!(((TextBox)sender).Text.Contains('.')))
                {
                    if (((TextBox)sender).Text.Length == 0) { ((TextBox)sender).Text = "0."; ((TextBox)sender).CaretIndex = ((TextBox)sender).Text.Length; }
                    else { ((TextBox)sender).Text += "."; ((TextBox)sender).CaretIndex = ((TextBox)sender).Text.Length; }
                }
            }
            if ((e.Text).ToCharArray()[e.Text.Length - 1] == '-' & !((TextBox)sender).Text.Contains('-')) { e.Handled = true; ((TextBox)sender).Text = "-" + ((TextBox)sender).Text; ((TextBox)sender).CaretIndex = ((TextBox)sender).Text.Length; }
            if ((e.Text).ToCharArray()[e.Text.Length - 1] == '+' & ((TextBox)sender).Text.Contains('-')) { e.Handled = true; ((TextBox)sender).Text=((TextBox)sender).Text.Substring(1); ((TextBox)sender).CaretIndex = ((TextBox)sender).Text.Length; }
 }

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