Silverlight 数字文本框? [英] Silverlight numeric textbox?

问题描述

我尝试创建自己的数字文本框，这是我的代码:

I tryed to create my own numeric textbox here is my code:

public class NumericTextBox : TextBox
{

    public NumericTextBox()
        : base()
    {
        this.Text = "0";
    }

    private void HandleKeyEvent(KeyEventArgs e)
    {
        e.Handled = true;
        if ((Keyboard.Modifiers & ModifierKeys.Alt) != 0)
        {
            return;
        }
        if (e.Key == Key.Back || e.Key == Key.Delete || e.Key == Key.Left || e.Key == Key.Right ||
            e.Key == Key.D0 || e.Key == Key.D1 || e.Key == Key.D2 || e.Key == Key.D3 || e.Key == Key.D4 || e.Key == Key.D5 || e.Key == Key.D6 ||
            e.Key == Key.D7 || e.Key == Key.D8 || e.Key == Key.D9 ||
            e.Key == Key.NumPad0 || e.Key == Key.NumPad1 || e.Key == Key.NumPad2 || e.Key == Key.NumPad3 || e.Key == Key.NumPad4 || e.Key == Key.NumPad5 || e.Key == Key.NumPad6 ||
            e.Key == Key.NumPad7 || e.Key == Key.NumPad8 || e.Key == Key.NumPad9)
        {
            e.Handled = false;
        }
        else if ((e.Key == Key.Subtract || (e.Key == Key.Unknown && e.PlatformKeyCode == 189)) && base.SelectionStart == 0 && (base.Text.Length == 0 || base.Text[0] != '-'))
        {
            e.Handled = false;
        }
    }

    protected override void OnKeyDown(KeyEventArgs e)
    {
        HandleKeyEvent(e);
        base.OnKeyDown(e);
    }

    protected override void OnKeyUp(KeyEventArgs e)
    {
        HandleKeyEvent(e);
        base.OnKeyUp(e);
    }
}

一切都像假设的那样，但是如果你按下 alt 和一些数字，它会创建对应于数字的 ascii 符号..有什么办法可以阻止alt + 数字组合?似乎 alt + 键只是被输入而没有抛出 OnKeyUp 或 OnKeyDown ...

everything works like supposed but if you press alt and some numbers it creates the ascii symbol corresponding to the number.. is there any way to block an "alt + number combination? it seems that alt + key just gets entered without going threw OnKeyUp or OnKeyDown...

推荐答案

我通过使用 TextChanged 事件让它工作这里是我的代码...

I got it working by using the TextChanged event here is my code...

public class NumericTextBox : TextBox
{

    int value;

    public NumericTextBox()
        : base()
    {
        this.Text = "0";
        this.TextChanged += new TextChangedEventHandler(NumericTextBox_TextChanged);
    }

    void NumericTextBox_TextChanged(object sender, TextChangedEventArgs e)
    {
        int selectionStart = base.SelectionStart;
        bool changed = false;
        List<char> charList = new List<char>();
        for (int i = 0; i < base.Text.Length; i++)
        {
            if (IsValidChar(base.Text[i], i))
            {
                charList.Add(base.Text[i]);
            }
            else
            {
                if (selectionStart >= i)
                {
                    selectionStart--;
                }
                changed = true;
            }
        }
        if (changed)
        {
            string text = new string(charList.ToArray());
            this.Text = text;
            this.SelectionStart = selectionStart;
        }
        int newValue;
        if (!int.TryParse(this.Text, out newValue))
        {
            this.Text = value.ToString();
            this.SelectionStart = this.Text.Length;
        }
        else
        {
            value = newValue;
        }
    }

    private bool IsValidChar(char c, int index)
    {
        return ((c == '-' && index == 0) || c == '0' || c == '1' || c == '2' || c == '3' || c == '4' || c == '5' || c == '6' || c == '7' || c == '8' || c == '9');
    }

    private void HandleKeyEvent(KeyEventArgs e)
    {
        e.Handled = true;
        if ((Keyboard.Modifiers & ModifierKeys.Control) == ModifierKeys.Control)
        {
            e.Handled = false;
        }
        if (e.Key == Key.Back || e.Key == Key.Delete || e.Key == Key.Left || e.Key == Key.Right ||
            e.Key == Key.D0 || e.Key == Key.D1 || e.Key == Key.D2 || e.Key == Key.D3 || e.Key == Key.D4 || e.Key == Key.D5 || e.Key == Key.D6 ||
            e.Key == Key.D7 || e.Key == Key.D8 || e.Key == Key.D9 ||
            e.Key == Key.NumPad0 || e.Key == Key.NumPad1 || e.Key == Key.NumPad2 || e.Key == Key.NumPad3 || e.Key == Key.NumPad4 || e.Key == Key.NumPad5 || e.Key == Key.NumPad6 ||
            e.Key == Key.NumPad7 || e.Key == Key.NumPad8 || e.Key == Key.NumPad9)
        {
            e.Handled = false;
        }
        else if ((e.Key == Key.Subtract || (e.Key == Key.Unknown && e.PlatformKeyCode == 189)) && base.SelectionStart == 0 && (base.Text.Length == 0 || base.Text[0] != '-'))
        {
            e.Handled = false;
        }
    }

    protected override void OnKeyDown(KeyEventArgs e)
    {
        HandleKeyEvent(e);
        base.OnKeyDown(e);
    }

    protected override void OnKeyUp(KeyEventArgs e)
    {
        HandleKeyEvent(e);
        base.OnKeyUp(e);
    }
}

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