C# 时间文本框

在我的应用程序中，我有一个

文本框

，用户可以在其中以

HH:mm:ss

格式输入时间值

文本框的xaml如下所示：

<TextBox xMinWidth="60" HorizontalAlignment="Left" Background="Transparent">
    <TextBox.Text>
        <Binding Path="FileTime" UpdateSourceTrigger="PropertyChanged" StringFormat="T" ConverterCulture="de-DE" />         
    </TextBox.Text>
</TextBox>

public class TextBoxExtensions
{
    public static readonly DependencyProperty EditStringFormatProperty = DependencyProperty.RegisterAttached(
        "EditStringFormat", typeof (string), typeof (TextBoxExtensions),
        new PropertyMetadata(default(string), OnEditStringFormatChanged));

    private static readonly DependencyProperty OriginalBindingExpressionProperty = DependencyProperty
        .RegisterAttached(
            "OriginalBindingExpression", typeof (BindingExpression), typeof (TextBoxExtensions),
            new PropertyMetadata(default(BindingExpression)));

    private static void OnEditStringFormatChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
    {
        TextBox textBox = d as TextBox;
        if (textBox == null)
            return;

        if (e.NewValue != null && e.OldValue == null)
        {
            textBox.IsKeyboardFocusedChanged += TextBoxOnIsKeyboardFocusedChanged;
        }
        else if (e.OldValue != null && e.NewValue == null)
        {
            textBox.IsKeyboardFocusedChanged -= TextBoxOnIsKeyboardFocusedChanged;
        }
    }

    private static void TextBoxOnIsKeyboardFocusedChanged(object sender, DependencyPropertyChangedEventArgs e)
    {
        TextBox textBox = sender as TextBox;

        if (textBox == null)
            return;

        if (GetOriginalBindingExpression(textBox) == null)
        {
            SetOriginalBindingExpression(textBox, textBox.GetBindingExpression(TextBox.TextProperty));
        }

        BindingExpression bindingExpression = GetOriginalBindingExpression(textBox);

        if (textBox.IsKeyboardFocused)
        {
            Binding parentBinding = bindingExpression.ParentBinding;
            Binding newBinding = new Binding(parentBinding.Path.Path)
            {
                ElementName = parentBinding.ElementName,
                Path = parentBinding.Path,
                Mode = parentBinding.Mode,
                UpdateSourceTrigger = parentBinding.UpdateSourceTrigger,
                StringFormat = "H:m:s"
            };
            foreach (ValidationRule validationRule in parentBinding.ValidationRules)
            {
                newBinding.ValidationRules.Add(validationRule);
            }
            textBox.SetBinding(TextBox.TextProperty, newBinding);
        }
        else
        {
            textBox.SetBinding(TextBox.TextProperty, bindingExpression.ParentBinding);
        }
    }

    public static void SetEditStringFormat(DependencyObject element, string value)
    {
        element.SetValue(EditStringFormatProperty, value);
    }

    public static string GetEditStringFormat(DependencyObject element)
    {
        return (string) element.GetValue(EditStringFormatProperty);
    }

    private static void SetOriginalBindingExpression(DependencyObject element, BindingExpression value)
    {
        element.SetValue(OriginalBindingExpressionProperty, value);
    }

    private static BindingExpression GetOriginalBindingExpression(DependencyObject element)
    {
        return (BindingExpression) element.GetValue(OriginalBindingExpressionProperty);
    }
}



ViewModel中的属性
FileTime
的类型为
DateTime

如果我尝试键入值13:15:45，则在键入4时，
文本框将显示13:15:04。如果我键入最后5个，则
文本框中的结果为13:15:045，这不是有效时间

如何使我的
TextBox
接受一个数字作为秒，而不附加前导零？
我找到了一个非常适合我的解决方案，并且每个
TextBox
都可以轻松地重复使用

我已经写了一个
附件属性
，它看起来像：

<TextBox xMinWidth="60" HorizontalAlignment="Left" Background="Transparent">
    <TextBox.Text>
        <Binding Path="FileTime" UpdateSourceTrigger="PropertyChanged" StringFormat="T" ConverterCulture="de-DE" />         
    </TextBox.Text>
</TextBox>

public class TextBoxExtensions
{
    public static readonly DependencyProperty EditStringFormatProperty = DependencyProperty.RegisterAttached(
        "EditStringFormat", typeof (string), typeof (TextBoxExtensions),
        new PropertyMetadata(default(string), OnEditStringFormatChanged));

    private static readonly DependencyProperty OriginalBindingExpressionProperty = DependencyProperty
        .RegisterAttached(
            "OriginalBindingExpression", typeof (BindingExpression), typeof (TextBoxExtensions),
            new PropertyMetadata(default(BindingExpression)));

    private static void OnEditStringFormatChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
    {
        TextBox textBox = d as TextBox;
        if (textBox == null)
            return;

        if (e.NewValue != null && e.OldValue == null)
        {
            textBox.IsKeyboardFocusedChanged += TextBoxOnIsKeyboardFocusedChanged;
        }
        else if (e.OldValue != null && e.NewValue == null)
        {
            textBox.IsKeyboardFocusedChanged -= TextBoxOnIsKeyboardFocusedChanged;
        }
    }

    private static void TextBoxOnIsKeyboardFocusedChanged(object sender, DependencyPropertyChangedEventArgs e)
    {
        TextBox textBox = sender as TextBox;

        if (textBox == null)
            return;

        if (GetOriginalBindingExpression(textBox) == null)
        {
            SetOriginalBindingExpression(textBox, textBox.GetBindingExpression(TextBox.TextProperty));
        }

        BindingExpression bindingExpression = GetOriginalBindingExpression(textBox);

        if (textBox.IsKeyboardFocused)
        {
            Binding parentBinding = bindingExpression.ParentBinding;
            Binding newBinding = new Binding(parentBinding.Path.Path)
            {
                ElementName = parentBinding.ElementName,
                Path = parentBinding.Path,
                Mode = parentBinding.Mode,
                UpdateSourceTrigger = parentBinding.UpdateSourceTrigger,
                StringFormat = "H:m:s"
            };
            foreach (ValidationRule validationRule in parentBinding.ValidationRules)
            {
                newBinding.ValidationRules.Add(validationRule);
            }
            textBox.SetBinding(TextBox.TextProperty, newBinding);
        }
        else
        {
            textBox.SetBinding(TextBox.TextProperty, bindingExpression.ParentBinding);
        }
    }

    public static void SetEditStringFormat(DependencyObject element, string value)
    {
        element.SetValue(EditStringFormatProperty, value);
    }

    public static string GetEditStringFormat(DependencyObject element)
    {
        return (string) element.GetValue(EditStringFormatProperty);
    }

    private static void SetOriginalBindingExpression(DependencyObject element, BindingExpression value)
    {
        element.SetValue(OriginalBindingExpressionProperty, value);
    }

    private static BindingExpression GetOriginalBindingExpression(DependencyObject element)
    {
        return (BindingExpression) element.GetValue(OriginalBindingExpressionProperty);
    }
}

其用法如下：

<TextBox x:Name="TxtHour" MinWidth="60" HorizontalAlignment="Left" MaxLength="8" Background="Transparent"
         Validation.ErrorTemplate="{StaticResource TextBoxErrorTemplate}"
         attachedProperties:TextBoxExtensions.EditStringFormat="H:m:s">
    <TextBox.Text>
        <Binding Path="FileTime" UpdateSourceTrigger="PropertyChanged" StringFormat="HH:mm:ss">
            <Binding.ValidationRules>
                <validationRules:StringIsTimeValidationRule />
            </Binding.ValidationRules>
        </Binding>
    </TextBox.Text>
</TextBox>


？为什么不尝试更改StringFormat？@Tomtom为什么会这样
HH:mm:s
的意思是：给我两个数字表示小时，如果小时<10，给我两个数字表示分钟，如果分钟<10，给我两个数字表示分钟，如果分钟<10，给我一个数字表示秒，如果秒>10，给我两个数字。你为什么不更新失去焦点的模型？在
PropertyChanged
中更新它是否很有必要？如果用户正在输入数据，并且只有在文本框失去焦点后才对文本进行格式化，那么将文本保留为未格式化如何？这也是数字格式的常见解决方案，如