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，文本框中的内容应该只有0-9和a-f（十六进制值），文本框应该根据十六进制值进行输入。
演示：
12 ab 32 a5 64
现在，如果我的光标位于最后并继续按退格键，则会在一般文本框中删除这些值。
现在如果我的光标位于a5的开头，并按“删除键”，则该值应该变为：
12 ab 32 56 4
如果我的光标位于a5的末尾并按下“删除键”，则不会发生任何事情。
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是给textbox的名称。我如何在我的基于MVVM的wpf应用程序中实现相同的情况。我有一个文本框，如上所述，它会收集输入。请帮忙!!!
答案 0 :(得分：3)
因为你正在使用MVVM - 你可以通过Value Converter来实现这一点 - 我主要是出于好奇 - 这似乎工作得很好但是目前需要每个控件的转换器实例因为它使用一个实例变量来缓存最后一个已知的好的十六进制值 - 我确定你可以将它与验证一起使用来改进它。
<强>更新 好吧这似乎有用（ish） - 只允许1-9＆amp; A-F，我不得不禁用文本框选择，因为它导致奇怪的结果 - 我使用附加行为来控制光标，可能有更好的方法来做到这一点，但我肯定不知道如何......
删除行为的工作方式与您的要求一致（如果您在对的末尾删除它什么也不做）。
玩一玩：）
更新2
进行了一些更改以使其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();
}
<强>视图模型
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);
}
}
文字框行为
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);
}
}
答案 1 :(得分：0)
尝试使用Extended WPF Toolkit中的MaskedTextBox。
对不起，我更专注于MaskedTextBox中可能的掩码值。十六进制数字没有掩码字符。 :(
你应该取消标记答案 我在Extended WPF Toolkit的跟踪器上发布了issue。