Implementing a simple value converter based on WPF

Value converters are a distinctive component in WPF projects. This article takes you to implement a standard value converter, first implementing an abstract base class, and then trying to implement it.

Create a directory named Converts in the root directory of the project, and then createandTwo files:

All codes are as follows:

using System;
using ;
using ;
using ;
using ;
using ;
using ;
using ;

namespace 
{
    public abstract class ValueConverterBase : IValueConverter
    {
        public abstract object Convert(object value, Type targetType, object parameter, CultureInfo culture);

        public virtual object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
        {
            return ;
        }
    }
}

---

using System;
using ;
using ;
using ;
using ;
using ;

namespace 
{
    public class DatetimeConverter : ValueConverterBase
    {
        public override object Convert(object value, Type targetType, object parameter, CultureInfo culture)
        {
            string result = "";
            if (value is DateTime data)
            {
                DateTime time = (DateTime)data;
                result = ("yyyy-MM-dd HH:mm:ss");
            }
            return result;
        }
    }
}

This code defines a value converter (ValueConverter), used to convert values ​​in data binding from one type to another in a WPF application. This converter is often used to format data or convert logic between the UI layer and the data model. Here is a detailed explanation of the code:

1. ValueConverterBase class

ValueConverterBaseIt is an abstract class that implementsIValueConverterinterface.IValueConverteris an interface in WPF to define value converters, usually used for value conversion in data binding.

Code parsing

public abstract class ValueConverterBase : IValueConverter
{
    public abstract object Convert(object value, Type targetType, object parameter, CultureInfo culture);

    public virtual object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
    {
        return ;
    }
}

Key points

Convertmethod:

• effect: Converts the value of the bound source to the target type.
• parameter：
  • value: The value of the binding source.
  • targetType: The type of the target attribute.
  • parameter: Optional conversion parameters.
  • culture: Locale settings for formatting and parsing.
• Return value: The converted value.

ConvertBackmethod:

• effect: Convert the target value back to the value of the binding source (for two-way binding).
• Default implementation:return, indicating that reverse conversion is not supported. This is a common behavior in one-way binding.

：

This is a special value, indicating that the property has no value set. In WPF, it is usually used to indicate that the binding failed or is not supported.

2. DatetimeConverter class

DatetimeConverteryesValueConverterBaseThe specific implementation ofDateTimeConvert value of type to string format.

Code parsing

public class DatetimeConverter : ValueConverterBase
{
    public override object Convert(object value, Type targetType, object parameter, CultureInfo culture)
    {
        string result = "";
        if (value is DateTime data)
        {
            DateTime time = (DateTime)data;
            result = ("yyyy-MM-dd HH:mm:ss");
        }
        return result;
    }
}

Key points

ConvertMethod implementation:

• examinevalueIs it trueDateTimetype.
• If so, format it as"yyyy-MM-dd HH:mm:ss"Format string.
• If not, return an empty string""。

ConvertBackmethod:

becauseDatetimeConverterNo explicit implementationConvertBackMethod, it inheritsValueConverterBaseThe default implementation of。

3. Use scenarios

In WPF,ValueConverterTypically used for data binding, converting values ​​in the data model into a format suitable for UI display. For example, you might have aDateTimeA property of type, but want to be displayed in a specific string format in the UI.

XAML Example

<>
    <local:DatetimeConverter x:Key="DatetimeConverter" />
</>

<TextBox Text="{Binding DateTimeProperty, Converter={StaticResource DatetimeConverter}}" />

• local:DatetimeConverter: QuoteDatetimeConverterkind.
• x:Key: Assign a key to the converter to reference in XAML.
• Binding:WillTextBoxofTextProperties binding toDateTimePropertyand useDatetimeConverterFormat.

4. Summary

ValueConverterBase: An abstract base class that implementsIValueConverterInterface, provides default reverse conversion behavior.

DatetimeConverter: A specific value converter for convertingDateTimeConvert a value of type to a string of a specific format.

Use scenarios: In WPF data binding, it is used to format values ​​in the data model into a format suitable for UI display.

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