c# - TextBox应该以特定格式显示十六进制文本

Question

我的xaml文件中有一个可编辑的文本框。现在，根据我的项目要求，文本框中的内容应仅为0-9，并且a-f(十六进制值)和文本框的内容应基于十六进制值进行输入。

示范:

12 ab 32 a5 64

现在，如果我的光标位于末尾，并且我继续按Backspace键，它将删除一般文本框中出现的值。

现在，如果我的光标位于a5的开头，并且我按了“删除键”，则该值应变为:

12 ab 32 56 4

如果我的光标位于a5的末尾，并且我按了“删除键”，则什么也不会发生。

我在C++应用程序中成功完成了如下操作:

void CMSP430CommPanel::textEditorTextChanged (TextEditor& editor)
{

if(&editor == m_texti2cWrite)
{       
    int count = 0;
    int location;

    String text1 = m_texti2cWrite->getText();
    String text = m_texti2cWrite->getText().removeCharacters(" ");
    String hexString = String::empty;   
    int countCaret = m_texti2cWrite->getCaretPosition();

        for(int i=0; i < text.length(); i++)
        {               
            hexString = hexString + String (&text[i], 1);
            if((i+1) % 2 == 0)
            {
                if(i != text.length()-1)
                {
                    hexString = hexString + T(" "); 
                    count ++;               
                }
            }
            count ++;
        }           

        m_texti2cWrite->setText(hexString,false);

        if(text1.length() == m_texti2cWrite->getCaretPosition())
        {
            m_texti2cWrite->setCaretPosition(count);
        }
        else
        {
            m_texti2cWrite->setCaretPosition(countCaret);
        }
}

}

其中m_texti2cWrite是指定给文本框的名称。我如何在基于MVVM的wpf应用程序中实现相同的情况。如上所述，我有一个文本框可以接受输入。请帮忙!!!

Answer 1

由于您使用的是MVVM-您可以通过Value Converter来执行此操作-我出于好奇心来尝试执行此操作-看起来效果很好，但由于使用了实例变量，因此目前每个控件都需要一个转换器实例来缓存最后一个已知的良好十六进制值-确保可以将其与验证结合使用以改善它。

更新
好的，这似乎可行(ish)-仅允许1-9和AF，我不得不禁用文本框选择，因为这会导致奇怪的结果-我使用了附加的行为来控制光标，可能有更好的方法这但我肯定不知道如何...

删除行为按您的要求进行(如果您删除了一对结尾，则不执行任何操作)。

玩一玩:)

更新2

进行了一些更改，使其可以与文本选择一起使用。

查看

<Window x:Class="WpfApplication1.MainWindow"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:local="clr-namespace:WpfApplication1"
    Title="MainWindow" Height="350" Width="525">
<Grid>
    <Grid.Resources>
        <local:HexStringConverter x:Key="HexConverter"></local:HexStringConverter>
    </Grid.Resources>
    <StackPanel>
        <TextBox local:TextBoxBehaviour.KeepCursorPosition="true"  VerticalAlignment="Center" Width="200" HorizontalAlignment="Center" Text="{Binding HexValue,Mode=TwoWay,Converter={StaticResource HexConverter},UpdateSourceTrigger=PropertyChanged}"></TextBox>

    </StackPanel>
</Grid>

查看背后的代码

public partial class MainWindow : Window
{
    public MainWindow()
    {
        this.DataContext = new MyViewModel();
        InitializeComponent();
    }

ViewModel

public class MyViewModel : INotifyPropertyChanged
{
    public event PropertyChangedEventHandler PropertyChanged;


    private void OnPropertyChanged(string propertyName)
    {
        if (PropertyChanged != null)
        {
            PropertyChanged.Invoke(this, new PropertyChangedEventArgs(propertyName));
        }
    }


    private string hexValue;
    public string HexValue
    {
        get
        {
            return hexValue;
        }
        set
        {
            hexValue = value;
            OnPropertyChanged("HexValue");
        }
    }


}

十六进制转换器

public class HexStringConverter : IValueConverter
{
    private string lastValidValue;
    public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
    {
        string ret = null;

        if (value != null && value is string)
        {
            var valueAsString = (string)value;
            var parts = valueAsString.ToCharArray();
            var formatted = parts.Select((p,i)=>(++i)%2==0 ? String.Concat(p.ToString()," ") : p.ToString());
            ret = String.Join(String.Empty,formatted).Trim();
        }


        return ret;
    }

    public object ConvertBack(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
    {
        object ret = null;
        if (value != null && value is string)
        {
            var valueAsString = ((string)value).Replace(" ",String.Empty).ToUpper();
            ret = lastValidValue = IsHex(valueAsString) ? valueAsString : lastValidValue;                
        }

        return ret;
    }


    private bool IsHex(string text)
    {
        var reg = new System.Text.RegularExpressions.Regex("^[0-9A-Fa-f]*$");
        return reg.IsMatch(text);
    }
}

文本框行为

public static class TextBoxBehaviour
{
    public static bool GetKeepCursorPosition(DependencyObject obj)
    {
        return (bool)obj.GetValue(KeepCursorPositionProperty);
    }

    public static void SetKeepCursorPosition(DependencyObject obj, bool value)
    {
        obj.SetValue(KeepCursorPositionProperty, value);
    }

    // Using a DependencyProperty as the backing store for KeepCursorPosition.  This enables animation, styling, binding, etc...
    public static readonly DependencyProperty KeepCursorPositionProperty =
        DependencyProperty.RegisterAttached("KeepCursorPosition", typeof(bool), typeof(TextBoxBehaviour), new UIPropertyMetadata(false, KeepCursorPosition));


    public static int GetPreviousCaretIndex(DependencyObject obj)
    {
        return (int)obj.GetValue(PreviousCaretIndexProperty);
    }

    public static void SetPreviousCaretIndex(DependencyObject obj, int value)
    {
        obj.SetValue(PreviousCaretIndexProperty, value);
    }

    // Using a DependencyProperty as the backing store for PreviousCaretIndex.  This enables animation, styling, binding, etc...
    public static readonly DependencyProperty PreviousCaretIndexProperty =
        DependencyProperty.RegisterAttached("PreviousCaretIndex", typeof(int), typeof(TextBoxBehaviour), new UIPropertyMetadata(0));


    public static string GetPreviousTextValue(DependencyObject obj)
    {
        return (string)obj.GetValue(PreviousTextValueProperty);
    }

    public static void SetPreviousTextValue(DependencyObject obj, string value)
    {
        obj.SetValue(PreviousTextValueProperty, value);
    }

    // Using a DependencyProperty as the backing store for PreviousTextValue.  This enables animation, styling, binding, etc...
    public static readonly DependencyProperty PreviousTextValueProperty =
        DependencyProperty.RegisterAttached("PreviousTextValue", typeof(string), typeof(TextBoxBehaviour), new UIPropertyMetadata(null));

    private static void KeepCursorPosition(DependencyObject sender, DependencyPropertyChangedEventArgs e)
    {
        var textBox = sender as TextBox;

        if (textBox != null)
        {
            textBox.PreviewKeyDown += new System.Windows.Input.KeyEventHandler(textBox_PreviewKeyDown);
            textBox.TextChanged += new TextChangedEventHandler(textBox_TextChanged);
            textBox.Unloaded += new RoutedEventHandler(textBox_Unloaded);
        }
        else
        {
            throw new ArgumentException("KeepCursorPosition only available for textboxes");
        }
    }

    static void textBox_Unloaded(object sender, RoutedEventArgs e)
    {
        var textBox = sender as TextBox;
        textBox.PreviewKeyDown -= new System.Windows.Input.KeyEventHandler(textBox_PreviewKeyDown);
        textBox.TextChanged -= new TextChangedEventHandler(textBox_TextChanged);
        textBox.Unloaded -= new RoutedEventHandler(textBox_Unloaded);
    }


    static void textBox_TextChanged(object sender, TextChangedEventArgs e)
    {
        //For some reason our e.Changes only ever contains 1 change of 1 character even if our
        //converter converts it to 2 chars with the additional space - hmmm?
        var textBox = sender as TextBox;
        var previousIndex = GetPreviousCaretIndex(textBox);
        var previousText = GetPreviousTextValue(textBox);

        var previousLen = !String.IsNullOrEmpty(previousText) ? previousText.Length : 0;
        var currentLen = textBox.Text.Length;
        var change = (currentLen - previousLen);

        var newCharIndex = Math.Max(1, (previousIndex + change));

        Debug.WriteLine("Text Changed Previous Caret Pos : {0}", previousIndex);
        Debug.WriteLine("Text Changed Change : {0}", change);
        Debug.WriteLine("Text Changed New Caret Pos : {0}", newCharIndex);

        textBox.CaretIndex = Math.Max(newCharIndex, previousIndex);
        SetPreviousCaretIndex(textBox, textBox.CaretIndex);
        SetPreviousTextValue(textBox, textBox.Text);
    }

    static void textBox_PreviewKeyDown(object sender, System.Windows.Input.KeyEventArgs e)
    {
        var textBox = sender as TextBox;
        Debug.WriteLine("Key Preview Caret Pos : {0}", textBox.CaretIndex);
        Debug.WriteLine("------------------------");
        SetPreviousCaretIndex(textBox, textBox.CaretIndex);
        SetPreviousTextValue(textBox, textBox.Text);
    }
}