¿Cómo definir restricciones de entrada de cuadro de texto?

Question

¿Cómo puedo restringir el cuadro de texto para aceptar sólo letras mayúsculas, o por ejemplo, dígitos, o no lo quiera poner ningún carácter especial?

Claro que es un pedazo de pastel para atrapar evento TextInput y manejar el texto aquí, pero es la forma correcta de hacer esto?

Answer 1

He hecho esto en el pasado con un comportamiento adjunto, que puede ser utilizado como esto:

<TextBox b:Masking.Mask="^\p{Lu}*$"/>

El código de comportamiento adjunto es el siguiente:

/// <summary>
/// Provides masking behavior for any <see cref="TextBox"/>.
/// </summary>
public static class Masking
{
    private static readonly DependencyPropertyKey _maskExpressionPropertyKey = DependencyProperty.RegisterAttachedReadOnly("MaskExpression",
        typeof(Regex),
        typeof(Masking),
        new FrameworkPropertyMetadata());

    /// <summary>
    /// Identifies the <see cref="Mask"/> dependency property.
    /// </summary>
    public static readonly DependencyProperty MaskProperty = DependencyProperty.RegisterAttached("Mask",
        typeof(string),
        typeof(Masking),
        new FrameworkPropertyMetadata(OnMaskChanged));

    /// <summary>
    /// Identifies the <see cref="MaskExpression"/> dependency property.
    /// </summary>
    public static readonly DependencyProperty MaskExpressionProperty = _maskExpressionPropertyKey.DependencyProperty;

    /// <summary>
    /// Gets the mask for a given <see cref="TextBox"/>.
    /// </summary>
    /// <param name="textBox">
    /// The <see cref="TextBox"/> whose mask is to be retrieved.
    /// </param>
    /// <returns>
    /// The mask, or <see langword="null"/> if no mask has been set.
    /// </returns>
    public static string GetMask(TextBox textBox)
    {
        if (textBox == null)
        {
            throw new ArgumentNullException("textBox");
        }

        return textBox.GetValue(MaskProperty) as string;
    }

    /// <summary>
    /// Sets the mask for a given <see cref="TextBox"/>.
    /// </summary>
    /// <param name="textBox">
    /// The <see cref="TextBox"/> whose mask is to be set.
    /// </param>
    /// <param name="mask">
    /// The mask to set, or <see langword="null"/> to remove any existing mask from <paramref name="textBox"/>.
    /// </param>
    public static void SetMask(TextBox textBox, string mask)
    {
        if (textBox == null)
        {
            throw new ArgumentNullException("textBox");
        }

        textBox.SetValue(MaskProperty, mask);
    }

    /// <summary>
    /// Gets the mask expression for the <see cref="TextBox"/>.
    /// </summary>
    /// <remarks>
    /// This method can be used to retrieve the actual <see cref="Regex"/> instance created as a result of setting the mask on a <see cref="TextBox"/>.
    /// </remarks>
    /// <param name="textBox">
    /// The <see cref="TextBox"/> whose mask expression is to be retrieved.
    /// </param>
    /// <returns>
    /// The mask expression as an instance of <see cref="Regex"/>, or <see langword="null"/> if no mask has been applied to <paramref name="textBox"/>.
    /// </returns>
    public static Regex GetMaskExpression(TextBox textBox)
    {
        if (textBox == null)
        {
            throw new ArgumentNullException("textBox");
        } 

        return textBox.GetValue(MaskExpressionProperty) as Regex;
    }

    private static void SetMaskExpression(TextBox textBox, Regex regex)
    {
        textBox.SetValue(_maskExpressionPropertyKey, regex);
    }

    private static void OnMaskChanged(DependencyObject dependencyObject, DependencyPropertyChangedEventArgs e)
    {
        var textBox = dependencyObject as TextBox;
        var mask = e.NewValue as string;
        textBox.PreviewTextInput -= textBox_PreviewTextInput;
        textBox.PreviewKeyDown -= textBox_PreviewKeyDown;
        DataObject.RemovePastingHandler(textBox, Pasting);

        if (mask == null)
        {
            textBox.ClearValue(MaskProperty);
            textBox.ClearValue(MaskExpressionProperty);
        }
        else
        {
            textBox.SetValue(MaskProperty, mask);
            SetMaskExpression(textBox, new Regex(mask, RegexOptions.Compiled | RegexOptions.IgnorePatternWhitespace));
            textBox.PreviewTextInput += textBox_PreviewTextInput;
            textBox.PreviewKeyDown += textBox_PreviewKeyDown;
            DataObject.AddPastingHandler(textBox, Pasting);
        }
    }

    private static void textBox_PreviewTextInput(object sender, TextCompositionEventArgs e)
    {
        var textBox = sender as TextBox;
        var maskExpression = GetMaskExpression(textBox);

        if (maskExpression == null)
        {
            return;
        }

        var proposedText = GetProposedText(textBox, e.Text);

        if (!maskExpression.IsMatch(proposedText))
        {
            e.Handled = true;
        }
    }

    private static void textBox_PreviewKeyDown(object sender, KeyEventArgs e)
    {
        var textBox = sender as TextBox;
        var maskExpression = GetMaskExpression(textBox);

        if (maskExpression == null)
        {
            return;
        }

        //pressing space doesn't raise PreviewTextInput - no idea why, but we need to handle
        //explicitly here
        if (e.Key == Key.Space)
        {
            var proposedText = GetProposedText(textBox, " ");

            if (!maskExpression.IsMatch(proposedText))
            {
                e.Handled = true;
            }
        }
    }

    private static void Pasting(object sender, DataObjectPastingEventArgs e)
    {
        var textBox = sender as TextBox;
        var maskExpression = GetMaskExpression(textBox);

        if (maskExpression == null)
        {
            return;
        }

        if (e.DataObject.GetDataPresent(typeof(string)))
        {
            var pastedText = e.DataObject.GetData(typeof(string)) as string;
            var proposedText = GetProposedText(textBox, pastedText);

            if (!maskExpression.IsMatch(proposedText))
            {
                e.CancelCommand();
            }
        }
        else
        {
            e.CancelCommand();
        }
    }

    private static string GetProposedText(TextBox textBox, string newText)
    {
        var text = textBox.Text;

        if (textBox.SelectionStart != -1)
        {
            text = text.Remove(textBox.SelectionStart, textBox.SelectionLength);
        }

        text = text.Insert(textBox.CaretIndex, newText);

        return text;
    }
}

Answer 2

He mejorado la respuesta de Kent por Boogaart también el manejo de las siguientes acciones que anteriormente podrían causar que el patrón sea violada:

• Retroceso
• Seleccionar y arrastrar el texto de una manera que puede violar el patrón
• comando Cortar

Por ejemplo, la respuesta de Kent Boogaart el usuario puede introducir "ac" mediante la introducción de primera "abc" y después borrar la "b" con la tecla de retroceso que viola la siguiente expresión regular

^(a|ab|abc)$

Uso (sin cambios):

<TextBox b:Masking.Mask="^\p{Lu}*$"/>

clase Máscara:

public static class Masking
{
    private static readonly DependencyPropertyKey _maskExpressionPropertyKey = DependencyProperty.RegisterAttachedReadOnly("MaskExpression",
            typeof(Regex),
            typeof(Masking),
            new FrameworkPropertyMetadata());

    /// <summary>
    /// Identifies the <see cref="Mask"/> dependency property.
    /// </summary>
    public static readonly DependencyProperty MaskProperty = DependencyProperty.RegisterAttached("Mask",
            typeof(string),
            typeof(Masking),
            new FrameworkPropertyMetadata(OnMaskChanged));

    /// <summary>
    /// Identifies the <see cref="MaskExpression"/> dependency property.
    /// </summary>
    public static readonly DependencyProperty MaskExpressionProperty = _maskExpressionPropertyKey.DependencyProperty;

    /// <summary>
    /// Gets the mask for a given <see cref="TextBox"/>.
    /// </summary>
    /// <param name="textBox">
    /// The <see cref="TextBox"/> whose mask is to be retrieved.
    /// </param>
    /// <returns>
    /// The mask, or <see langword="null"/> if no mask has been set.
    /// </returns>
    public static string GetMask(TextBox textBox)
    {
        if (textBox == null)
        {
            throw new ArgumentNullException("textBox");
        }

        return textBox.GetValue(MaskProperty) as string;
    }

    /// <summary>
    /// Sets the mask for a given <see cref="TextBox"/>.
    /// </summary>
    /// <param name="textBox">
    /// The <see cref="TextBox"/> whose mask is to be set.
    /// </param>
    /// <param name="mask">
    /// The mask to set, or <see langword="null"/> to remove any existing mask from <paramref name="textBox"/>.
    /// </param>
    public static void SetMask(TextBox textBox, string mask)
    {
        if (textBox == null)
        {
            throw new ArgumentNullException("textBox");
        }

        textBox.SetValue(MaskProperty, mask);
    }

    /// <summary>
    /// Gets the mask expression for the <see cref="TextBox"/>.
    /// </summary>
    /// <remarks>
    /// This method can be used to retrieve the actual <see cref="Regex"/> instance created as a result of setting the mask on a <see cref="TextBox"/>.
    /// </remarks>
    /// <param name="textBox">
    /// The <see cref="TextBox"/> whose mask expression is to be retrieved.
    /// </param>
    /// <returns>
    /// The mask expression as an instance of <see cref="Regex"/>, or <see langword="null"/> if no mask has been applied to <paramref name="textBox"/>.
    /// </returns>
    public static Regex GetMaskExpression(TextBox textBox)
    {
        if (textBox == null)
        {
            throw new ArgumentNullException("textBox");
        }

        return textBox.GetValue(MaskExpressionProperty) as Regex;
    }

    private static void SetMaskExpression(TextBox textBox, Regex regex)
    {
        textBox.SetValue(_maskExpressionPropertyKey, regex);
    }

    private static void OnMaskChanged(DependencyObject dependencyObject, DependencyPropertyChangedEventArgs e)
    {
        var textBox = dependencyObject as TextBox;
        var mask = e.NewValue as string;
        textBox.PreviewTextInput -= textBox_PreviewTextInput;
        textBox.PreviewKeyDown -= textBox_PreviewKeyDown;
        DataObject.RemovePastingHandler(textBox, Pasting);
        DataObject.RemoveCopyingHandler(textBox, NoDragCopy);
        CommandManager.RemovePreviewExecutedHandler(textBox, NoCutting);


        if (mask == null)
        {
            textBox.ClearValue(MaskProperty);
            textBox.ClearValue(MaskExpressionProperty);
        }
        else
        {
            textBox.SetValue(MaskProperty, mask);
            SetMaskExpression(textBox, new Regex(mask, RegexOptions.Compiled | RegexOptions.IgnorePatternWhitespace));
            textBox.PreviewTextInput += textBox_PreviewTextInput;
            textBox.PreviewKeyDown += textBox_PreviewKeyDown;
            DataObject.AddPastingHandler(textBox, Pasting);
            DataObject.AddCopyingHandler(textBox, NoDragCopy);
            CommandManager.AddPreviewExecutedHandler(textBox, NoCutting);
        }
    }

    private static void NoCutting(object sender, ExecutedRoutedEventArgs e)
    {
        if(e.Command == ApplicationCommands.Cut)
        {
            e.Handled = true;
        }
    }

    private static void NoDragCopy(object sender, DataObjectCopyingEventArgs e)
    {
        if (e.IsDragDrop)
        {
            e.CancelCommand();
        }
    }

    private static void textBox_PreviewTextInput(object sender, TextCompositionEventArgs e)
    {
        var textBox = sender as TextBox;
        var maskExpression = GetMaskExpression(textBox);

        if (maskExpression == null)
        {
            return;
        }

        var proposedText = GetProposedText(textBox, e.Text);

        if (!maskExpression.IsMatch(proposedText))
        {
            e.Handled = true;
        }
    }

    private static void textBox_PreviewKeyDown(object sender, KeyEventArgs e)
    {
        var textBox = sender as TextBox;
        var maskExpression = GetMaskExpression(textBox);

        if (maskExpression == null)
        {
            return;
        }

        string proposedText = null;

        //pressing space doesn't raise PreviewTextInput, reasons here http://social.msdn.microsoft.com/Forums/en-US/wpf/thread/446ec083-04c8-43f2-89dc-1e2521a31f6b?prof=required
        if (e.Key == Key.Space)
        {
            proposedText = GetProposedText(textBox, " ");
        }
        // Same story with backspace
        else if(e.Key == Key.Back)
        {
            proposedText = GetProposedTextBackspace(textBox);
        }

        if (proposedText != null && proposedText != string.Empty && !maskExpression.IsMatch(proposedText))
        {
            e.Handled = true;
        }

    }

    private static void Pasting(object sender, DataObjectPastingEventArgs e)
    {
        var textBox = sender as TextBox;
        var maskExpression = GetMaskExpression(textBox);

        if (maskExpression == null)
        {
            return;
        }

        if (e.DataObject.GetDataPresent(typeof(string)))
        {
            var pastedText = e.DataObject.GetData(typeof(string)) as string;
            var proposedText = GetProposedText(textBox, pastedText);

            if (!maskExpression.IsMatch(proposedText))
            {
                e.CancelCommand();
            }
        }
        else
        {
            e.CancelCommand();
        }
    }

    private static string GetProposedTextBackspace(TextBox textBox)
    {
        var text = GetTextWithSelectionRemoved(textBox);
        if (textBox.SelectionStart > 0 && textBox.SelectionLength == 0)
        {
            text = text.Remove(textBox.SelectionStart-1, 1);
        }

        return text;
    }


    private static string GetProposedText(TextBox textBox, string newText)
    {
        var text = GetTextWithSelectionRemoved(textBox);
        text = text.Insert(textBox.CaretIndex, newText);

        return text;
    }

    private static string GetTextWithSelectionRemoved(TextBox textBox)
    {
        var text = textBox.Text;

        if (textBox.SelectionStart != -1)
        {
            text = text.Remove(textBox.SelectionStart, textBox.SelectionLength);
        }
        return text;
    }
}

Answer 3

He cambiado el código de VitalyB para apoyar temas de color. En lugar de bloquear la entrada del usuario si no cumple con el guión expresiones regulares, simplemente pone de relieve el cuadro de texto. El cuadro de texto será el tema por defecto y sin interacción y, a continuación, por defecto un color verde claro o rojo, dependiendo del valor después de la entrada está ajustado. También puede configurar el fracaso y pasar los colores mediante programación con:

b:ColorMasking.PassColor = "Hexadecimal Value"
b:ColorMasking.FailColor = "Hexadecimal Value"

La clase es el siguiente:

public class ColorMasking : DependencyObject
{
    private static readonly DependencyPropertyKey _maskExpressionPropertyKey = DependencyProperty.RegisterAttachedReadOnly("MaskExpression",
            typeof(Regex),
            typeof(ColorMasking),
            new FrameworkPropertyMetadata());

    /// <summary>
    /// Identifies the <see cref="Mask"/> dependency property.
    /// </summary>
    /// 
    public static readonly DependencyProperty PassColorProperty = DependencyProperty.RegisterAttached("PassColor",
            typeof(string),
            typeof(ColorMasking),
            new PropertyMetadata("#99FF99"));

    public static void SetPassColor(DependencyObject obj, string passColor)
    {
        obj.SetValue(PassColorProperty, passColor);
    }

    public static string GetPassColor(DependencyObject obj)
    {
        return (string)obj.GetValue(PassColorProperty);
    }


    public static readonly DependencyProperty FailColorProperty = DependencyProperty.RegisterAttached("FailColor",
            typeof(string),
            typeof(ColorMasking),
            new PropertyMetadata("#FFCCFF"));

    public static void SetFailColor(DependencyObject obj, string failColor)
    {
        obj.SetValue(FailColorProperty, failColor);
    }

    public static string GetFailColor(DependencyObject obj)
    {
        return (string)obj.GetValue(FailColorProperty);
    }

    public static readonly DependencyProperty MaskProperty = DependencyProperty.RegisterAttached("Mask",
            typeof(string),
            typeof(ColorMasking),
            new FrameworkPropertyMetadata(OnMaskChanged));

    private static void OnPassColorChanged(DependencyObject dependencyObject, DependencyPropertyChangedEventArgs e)
    {
        var textBox = dependencyObject as TextBox;
        var color = e.NewValue as string;
        textBox.SetValue(PassColorProperty, color);
    }

    /// <summary>
    /// Identifies the <see cref="MaskExpression"/> dependency property.
    /// </summary>
    public static readonly DependencyProperty MaskExpressionProperty = _maskExpressionPropertyKey.DependencyProperty;

    /// <summary>
    /// Gets the mask for a given <see cref="TextBox"/>.
    /// </summary>
    /// <param name="textBox">
    /// The <see cref="TextBox"/> whose mask is to be retrieved.
    /// </param>
    /// <returns>
    /// The mask, or <see langword="null"/> if no mask has been set.
    /// </returns>
    public static string GetMask(TextBox textBox)
    {
        if (textBox == null)
        {
            throw new ArgumentNullException("textBox");
        }

        return textBox.GetValue(MaskProperty) as string;
    }

    /// <summary>
    /// Sets the mask for a given <see cref="TextBox"/>.
    /// </summary>
    /// <param name="textBox">
    /// The <see cref="TextBox"/> whose mask is to be set.
    /// </param>
    /// <param name="mask">
    /// The mask to set, or <see langword="null"/> to remove any existing mask from <paramref name="textBox"/>.
    /// </param>
    public static void SetMask(TextBox textBox, string mask)
    {
        if (textBox == null)
        {
            throw new ArgumentNullException("textBox");
        }

        textBox.SetValue(MaskProperty, mask);
    }

    /// <summary>
    /// Gets the mask expression for the <see cref="TextBox"/>.
    /// </summary>
    /// <remarks>
    /// This method can be used to retrieve the actual <see cref="Regex"/> instance created as a result of setting the mask on a <see cref="TextBox"/>.
    /// </remarks>
    /// <param name="textBox">
    /// The <see cref="TextBox"/> whose mask expression is to be retrieved.
    /// </param>
    /// <returns>
    /// The mask expression as an instance of <see cref="Regex"/>, or <see langword="null"/> if no mask has been applied to <paramref name="textBox"/>.
    /// </returns>
    public static Regex GetMaskExpression(TextBox textBox)
    {
        if (textBox == null)
        {
            throw new ArgumentNullException("textBox");
        }

        return textBox.GetValue(MaskExpressionProperty) as Regex;
    }

    private static void SetMaskExpression(TextBox textBox, Regex regex)
    {
        textBox.SetValue(_maskExpressionPropertyKey, regex);
    }

    private static void OnMaskChanged(DependencyObject dependencyObject, DependencyPropertyChangedEventArgs e)
    {
        var textBox = dependencyObject as TextBox;
        var mask = e.NewValue as string;
        textBox.PreviewTextInput -= textBox_PreviewTextInput;
        textBox.PreviewKeyDown -= textBox_PreviewKeyDown;
        DataObject.RemovePastingHandler(textBox, Pasting);
        DataObject.RemoveCopyingHandler(textBox, NoDragCopy);
        CommandManager.RemovePreviewExecutedHandler(textBox, NoCutting);

        if (mask == null)
        {
            textBox.ClearValue(MaskProperty);
            textBox.ClearValue(MaskExpressionProperty);
        }
        else
        {
            textBox.SetValue(MaskProperty, mask);
            SetMaskExpression(textBox, new Regex(mask, RegexOptions.Compiled | RegexOptions.IgnorePatternWhitespace));
            textBox.PreviewTextInput += textBox_PreviewTextInput;
            textBox.PreviewKeyDown += textBox_PreviewKeyDown;
            DataObject.AddPastingHandler(textBox, Pasting);
            DataObject.AddCopyingHandler(textBox, NoDragCopy);
            CommandManager.AddPreviewExecutedHandler(textBox, NoCutting);
        }
    }

    private static void NoCutting(object sender, ExecutedRoutedEventArgs e)
    {
        if (e.Command == ApplicationCommands.Cut)
        {
            e.Handled = true;
        }
    }

    private static void NoDragCopy(object sender, DataObjectCopyingEventArgs e)
    {
        if (e.IsDragDrop)
        {
            e.CancelCommand();
        }
    }

    private static void textBox_PreviewTextInput(object sender, TextCompositionEventArgs e)
    {
        var textBox = sender as TextBox;
        var maskExpression = GetMaskExpression(textBox);

        string passHex = (string)textBox.GetValue(PassColorProperty);
        string failHex = (string)textBox.GetValue(FailColorProperty);
        Color passColor = Extensions.ToColorFromHex(passHex);
        Color failColor = Extensions.ToColorFromHex(failHex);

        if (maskExpression == null)
        {
            return;
        }

        var proposedText = GetProposedText(textBox, e.Text);

        if (!maskExpression.IsMatch(proposedText))
        {
            textBox.Background = new SolidColorBrush(failColor);
        }
        else
        {
            textBox.Background = new SolidColorBrush(passColor);
        }
    }

    private static void textBox_PreviewKeyDown(object sender, KeyEventArgs e)
    {
        var textBox = sender as TextBox;
        var maskExpression = GetMaskExpression(textBox);

        string passHex = (string)textBox.GetValue(PassColorProperty);
        string failHex = (string)textBox.GetValue(FailColorProperty);
        Color passColor = Extensions.ToColorFromHex(passHex);
        Color failColor = Extensions.ToColorFromHex(failHex);

        if (maskExpression == null)
        {
            return;
        }

        string proposedText = null;

        //pressing space doesn't raise PreviewTextInput, reasons here http://social.msdn.microsoft.com/Forums/en-US/wpf/thread/446ec083-04c8-43f2-89dc-1e2521a31f6b?prof=required
        if (e.Key == Key.Space)
        {
            proposedText = GetProposedText(textBox, " ");
        }
        // Same story with backspace
        else if (e.Key == Key.Back)
        {
            proposedText = GetProposedTextBackspace(textBox);
        }

        if (proposedText != null && !maskExpression.IsMatch(proposedText))
        {
            textBox.Background = new SolidColorBrush(failColor);
        }
        else
        {
            textBox.Background = new SolidColorBrush(passColor);
        }

    }

    private static void Pasting(object sender, DataObjectPastingEventArgs e)
    {
        TextBox textBox = sender as TextBox;
        var maskExpression = GetMaskExpression(textBox);

        string passHex = (string)textBox.GetValue(PassColorProperty);
        string failHex = (string)textBox.GetValue(FailColorProperty);
        Color passColor = Extensions.ToColorFromHex(passHex);
        Color failColor = Extensions.ToColorFromHex(failHex);

        if (maskExpression == null)
        {
            return;
        }

        if (e.DataObject.GetDataPresent(typeof(string)))
        {
            var pastedText = e.DataObject.GetData(typeof(string)) as string;
            var proposedText = GetProposedText(textBox, pastedText);

            if (!maskExpression.IsMatch(proposedText))
            {
                textBox.Background = new SolidColorBrush(failColor);
            }
            else
            {
                textBox.Background = new SolidColorBrush(passColor);
            }
        }
        else
        {
            textBox.Background = new SolidColorBrush(failColor);
        }
    }

    private static string GetProposedTextBackspace(TextBox textBox)
    {
        var text = GetTextWithSelectionRemoved(textBox);
        if (textBox.SelectionStart > 0)
        {
            text = text.Remove(textBox.SelectionStart - 1, 1);
        }

        return text;
    }


    private static string GetProposedText(TextBox textBox, string newText)
    {
        var text = GetTextWithSelectionRemoved(textBox);
        text = text.Insert(textBox.CaretIndex, newText);

        return text;
    }

    private static string GetTextWithSelectionRemoved(TextBox textBox)
    {
        var text = textBox.Text;

        if (textBox.SelectionStart != -1)
        {
            text = text.Remove(textBox.SelectionStart, textBox.SelectionLength);
        }
        return text;
    }
}

Para ejecutar la secuencia de comandos requiere una clase escrita por Aaron C, se explica aquí: Silverlight / WPF establece elipse con el color hexadecimal se muestra aquí: http: //www.wiredprairie.us/blog/index.php/archives/659

El código está por debajo en caso de que el sitio web es movida:

public static class Extensions
{
    public static void SetFromHex(this Color c, string hex)
    {
        Color c1 = ToColorFromHex(hex);

        c.A = c1.A;
        c.R = c1.R;
        c.G = c1.G;
        c.B = c1.B;
    }

    public static Color ToColorFromHex(string hex)
    {
        if (string.IsNullOrEmpty(hex))
        {
            throw new ArgumentNullException("hex");
        }

        // remove any "#" characters
        while (hex.StartsWith("#"))
        {
            hex = hex.Substring(1);
        }

        int num = 0;
        // get the number out of the string
        if (!Int32.TryParse(hex, System.Globalization.NumberStyles.HexNumber, null, out num))
        {
            throw new ArgumentException("Color not in a recognized Hex format.");
        }

        int[] pieces = new int[4];
        if (hex.Length > 7)
        {
            pieces[0] = ((num >> 24) & 0x000000ff);
            pieces[1] = ((num >> 16) & 0x000000ff);
            pieces[2] = ((num >> 8) & 0x000000ff);
            pieces[3] = (num & 0x000000ff);
        }
        else if (hex.Length > 5)
        {
            pieces[0] = 255;
            pieces[1] = ((num >> 16) & 0x000000ff);
            pieces[2] = ((num >> 8) & 0x000000ff);
            pieces[3] = (num & 0x000000ff);
        }
        else if (hex.Length == 3)
        {
            pieces[0] = 255;
            pieces[1] = ((num >> 8) & 0x0000000f);
            pieces[1] += pieces[1] * 16;
            pieces[2] = ((num >> 4) & 0x000000f);
            pieces[2] += pieces[2] * 16;
            pieces[3] = (num & 0x000000f);
            pieces[3] += pieces[3] * 16;
        }
        return Color.FromArgb((byte)pieces[0], (byte)pieces[1], (byte)pieces[2], (byte)pieces[3]);
    }

}

Answer 4

private void TextBox1_SelectionChanged(object sender, RoutedEventArgs e)
{
    string txt = TextBox1.Text;
    if (txt != "")
    {
        TextBox1.Text = Regex.Replace(TextBox1.Text, "[^0-9]", "");
        if (txt != TextBox1.Text)
        {
            TextBox1.Select(TextBox1.Text.Length, 0);
        }
    }
}

Answer 5

A continuación, sin embargo, es otra versión de las soluciones existentes aquí. Es un comportamiento que simula un evento "TextChanging" que proporciona el texto anterior, el nuevo texto y una bandera para cancelar el cambio. De esta manera podemos poner en práctica lo que queremos filtro.

Me libré del manipulador "PreviewKeyDown" que se utiliza sólo para el carácter de espacio. Cuadro de texto parece manejar todo con comandos enrutados y "espacio" tiene su propia commmand, aunque no es público. También he añadido soporte para atajos de teclado cargos adicionales como "Ctrl + Retroceso" (borrar la palabra anterior).

public class TextChangingBehavior : Behavior<TextBox>
{
    public event EventHandler<TextChangingEventArgs> TextChanging;

    protected override void OnAttached()
    {
        base.OnAttached();

        AssociatedObject.PreviewTextInput += OnPreviewTextInput;
        CommandManager.AddPreviewExecutedHandler(AssociatedObject, OnPreviewExecutedHandler);
        DataObject.AddCopyingHandler(AssociatedObject, OnCopying);
        DataObject.AddPastingHandler(AssociatedObject, OnPasting);
    }

    protected override void OnDetaching()
    {
        base.OnDetaching();

        AssociatedObject.PreviewTextInput -= OnPreviewTextInput;
        CommandManager.RemovePreviewExecutedHandler(AssociatedObject, OnPreviewExecutedHandler);
        DataObject.RemoveCopyingHandler(AssociatedObject, OnCopying);
        DataObject.RemovePastingHandler(AssociatedObject, OnPasting);
    }

    #region Text

    private enum CharCategory
    {
        LetterOrDigit,
        Whitespace,
        Other
    }

    private CharCategory GetCharCategory(char c)
    {
        if (char.IsLetterOrDigit(c))
            return CharCategory.LetterOrDigit;
        else if (char.IsWhiteSpace(c))
            return CharCategory.Whitespace;
        else
            return CharCategory.Other;
    }

    private string GetText(string input = null)
    {
        var box = AssociatedObject;
        var text = box.Text ?? string.Empty;
        if (input != null)
        {
            // Delete selection
            var deleteCount = box.SelectionLength;
            if (deleteCount > 0)
                text = text.Remove(box.SelectionStart, deleteCount);
            // Insert input
            if (input.Length > 0)
                text = text.Insert(box.CaretIndex, input);
        }
        return text;
    }

    #endregion

    private void OnPreviewExecutedHandler(object sender, ExecutedRoutedEventArgs e)
    {
        var box = AssociatedObject;
        var selectionExists = box.SelectionLength > 0;
        var caretIndex = box.CaretIndex;
        string newText = null;

        if (e.Command == ApplicationCommands.Cut)
        {
            if (selectionExists)
                newText = GetText(string.Empty);
        }
        else if (e.Command == EditingCommands.Backspace)
        {
            if (selectionExists)
                newText = GetText(string.Empty);
            else if (caretIndex > 0)
                newText = GetText().Remove(caretIndex - 1, 1);
        }
        else if (e.Command == EditingCommands.Delete)
        {
            if (selectionExists)
                newText = GetText(string.Empty);
            else
            {
                newText = GetText();
                if (caretIndex >= newText.Length)
                    newText = null;
                else
                    newText = newText.Remove(caretIndex, 1);
            }
        }
        else if (e.Command == EditingCommands.DeletePreviousWord)
        {
            if (selectionExists)
                newText = GetText(string.Empty);
            else if (caretIndex > 0)
            {
                newText = GetText();
                var startIndex = caretIndex;
                // Include whitespaces
                do
                    startIndex--;
                while (startIndex > 0 && char.IsWhiteSpace(newText[startIndex]));
                // Include the next block
                var currentCategory = GetCharCategory(newText[startIndex]);
                while (startIndex > 0 && GetCharCategory(newText[startIndex - 1]) == currentCategory)
                    startIndex--;

                newText = newText.Remove(startIndex, caretIndex - startIndex);
            }
        }
        else if (e.Command == EditingCommands.DeleteNextWord)
        {
            if (selectionExists)
                newText = GetText(string.Empty);
            else
            {
                newText = GetText();
                if (caretIndex >= newText.Length)
                    newText = null;
                else
                {
                    var endIndex = caretIndex + 1;
                    // Include the current block
                    var currentCategory = GetCharCategory(newText[caretIndex]);
                    while (endIndex < newText.Length && GetCharCategory(newText[endIndex]) == currentCategory)
                        endIndex++;
                    // Include whitespaces
                    while (endIndex < newText.Length && char.IsWhiteSpace(newText[endIndex]))
                        endIndex++;

                    newText = newText.Remove(caretIndex, endIndex - caretIndex);
                }
            }
        }
        else if (e.Command is RoutedUICommand cmd && new[] { "Space", "ShiftSpace" }.Contains(cmd.Name))
        {
            newText = GetText(" ");
        }

        if (newText != null && OnProcessChange(newText))
            e.Handled = true;
    }

    private void OnCopying(object sender, DataObjectCopyingEventArgs e)
    {
        if (e.IsDragDrop)
        {
            if (OnProcessChange(GetText(string.Empty)))
                e.CancelCommand();
        }
    }

    private void OnPasting(object sender, DataObjectPastingEventArgs e)
    {
        if (e.DataObject.GetDataPresent(typeof(string)))
        {
            if (OnProcessChange(GetText((string)e.DataObject.GetData(typeof(string)))))
                e.CancelCommand();
        }
    }

    private void OnPreviewTextInput(object sender, TextCompositionEventArgs e)
    {
        if (!string.IsNullOrEmpty(e.Text))
        {
            if (OnProcessChange(GetText(e.Text)))
                e.Handled = true;
        }
    }

    private bool OnProcessChange(string newValue)
    {
        var oldValue = GetText();

        if (string.Equals(oldValue, newValue, StringComparison.Ordinal))
            return false;
        else
        {
            var args = new TextChangingEventArgs(oldValue, newValue);
            OnTextChanging(args);
            return args.Cancel;
        }
    }

    protected virtual void OnTextChanging(TextChangingEventArgs e)
    {
        TextChanging?.Invoke(this, e);
    }
}

public class TextChangingEventArgs : EventArgs
{
    public string OldValue { get; }

    public string NewValue { get; }

    public bool Cancel { get; set; }

    public TextChangingEventArgs(string oldValue, string newValue)
    {
        OldValue = oldValue;
        NewValue = newValue;
    }
}

Answer 6

Otra posible solución es el uso de uno de los "Masked TextBox" wpf aplicación utilizando la clase "MaskedTextProvider" que se utiliza por el "MaskedTextBox" de Winforms.

Dos posibles soluciones se encuentran aquí -> https://wpftoolkit.codeplex.com/wikipage? title = MaskedTextBox y aquí -> http: //marlongrech.wordpress .com / 2007/10/28 / enmascarado-cuadro de texto /