WPF技巧-常用的Converter集合(更新ing)

示例 1：BooleanToVisibilityConverter

将布尔值转换为 Visibility（如 true => Visible, false => Collapsed）

public class BooleanToVisibilityConverter : IValueConverter
{
    public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
    {
        if (value is bool booleanValue)
            return booleanValue ? Visibility.Visible : Visibility.Collapsed;

        return Visibility.Collapsed;
    }

    public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
    {
        if (value is Visibility visibility)
            return visibility == Visibility.Visible;

        return false;
    }
}

---

示例 2：InvertedBooleanToVisibilityConverter

反向布尔转可见性（true => Collapsed, false => Visible）

public class InvertedBooleanToVisibilityConverter : IValueConverter
{
    public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
    {
        if (value is bool booleanValue)
            return !booleanValue ? Visibility.Visible : Visibility.Collapsed;

        return Visibility.Visible;
    }

    public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
    {
        if (value is Visibility visibility)
            return visibility != Visibility.Visible;

        return true;
    }
}

---

示例 3：StringToColorConverter

将字符串转换为 Color（支持 Hex、Named 等格式）

public class StringToColorConverter : IValueConverter
{
    public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
    {
        if (value is string colorStr)
        {
            try
            {
                return (Color)ColorConverter.ConvertFromString(colorStr);
            }
            catch { }
        }
        return Colors.Transparent;
    }

    public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
    {
        if (value is Color color)
            return color.ToString();

        return string.Empty;
    }
}

---

示例 4：StringToBrushConverter

将字符串转换为 Brush（支持 Hex、Named）

public class StringToBrushConverter : IValueConverter
{
    public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
    {
        if (value is string brushStr)
        {
            try
            {
                return new SolidColorBrush((Color)ColorConverter.ConvertFromString(brushStr));
            }
            catch { }
        }
        return Brushes.Transparent;
    }

    public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
    {
        if (value is SolidColorBrush brush)
            return brush.Color.ToString();

        return string.Empty;
    }
}

---

示例 5：NullToVisibilityConverter

将 null 或空对象转换为 Visibility（非空显示，为空隐藏）

public class NullToVisibilityConverter : IValueConverter
{
    public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
    {
        return value == null || value is string str && string.IsNullOrEmpty(str)
            ? Visibility.Collapsed
            : Visibility.Visible;
    }

    public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
    {
        throw new NotImplementedException();
    }
}

---

示例 6：EnumToVisibilityConverter

根据枚举值是否匹配某个参数来决定是否显示

public class EnumToVisibilityConverter : IValueConverter
{
    public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
    {
        if (value == null || parameter == null)
            return Visibility.Collapsed;

        return value.ToString() == parameter.ToString()
            ? Visibility.Visible
            : Visibility.Collapsed;
    }

    public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
    {
        if (value is Visibility visible && visible == Visibility.Visible && parameter != null)
            return parameter;

        return Binding.DoNothing;
    }
}

XAML 使用：

<TextBlock Text="Only shown when Status is Active"
           Visibility="{Binding Status, Converter={StaticResource EnumToVisibilityConverter}, ConverterParameter=Active}" />

---

示例 7：DoubleToOpacityConverter

将数值映射为透明度（0.0 - 1.0）

public class DoubleToOpacityConverter : IValueConverter
{
    public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
    {
        if (value is double opacity)
            return opacity >= 0 && opacity <= 1 ? opacity : 1.0;

        return 1.0;
    }

    public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
    {
        if (value is double opacity)
            return opacity;

        return 1.0;
    }
}

---

✅ 注册与使用方式（XAML）

1. 在资源中注册：

<Window.Resources>
    <converters:BooleanToVisibilityConverter x:Key="BooleanToVisibilityConverter" />
    <converters:StringToBrushConverter x:Key="StringToBrushConverter" />
    
Window.Resources>

2. 在绑定中使用：

<Button Content="Toggle" 
        Visibility="{Binding IsEnabled, Converter={StaticResource BooleanToVisibilityConverter}}" />

<TextBlock Text="Colored Text"
           Foreground="{Binding TextColor, Converter={StaticResource StringToBrushConverter}}" />