字符串格式正负值和条件颜色格式化 XAML

Question

我正在寻找一种使用以下标准格式化我的结果的简单方法：如果是肯定的，添加一个加号并将其显示为绿色，如果它是负数，则添加一个减号并显示为红色。

我已经完成了一半，我只是不知道获得颜色格式的最简单方法是什么。有没有不使用值转换器的方法？

<TextBlock Text="{Binding Path=ActualValue, StringFormat='({0:+0.0;-0.0})'}"></TextBlock>

解决这个问题最聪明的方法是什么？谢谢你。

Answer 1

我认为没有转换器就无法做到这一点。这是可以为数字类型（除了char）完成这项工作的一个：

[ValueConversion(typeof(int), typeof(Brush))]
[ValueConversion(typeof(double), typeof(Brush))]
[ValueConversion(typeof(byte), typeof(Brush))]
[ValueConversion(typeof(long), typeof(Brush))]
[ValueConversion(typeof(float), typeof(Brush))]
[ValueConversion(typeof(uint), typeof(Brush))]
[ValueConversion(typeof(short), typeof(Brush))]
[ValueConversion(typeof(sbyte), typeof(Brush))]
[ValueConversion(typeof(ushort), typeof(Brush))]
[ValueConversion(typeof(ulong), typeof(Brush))]
[ValueConversion(typeof(decimal), typeof(Brush))]
public class SignToBrushConverter : IValueConverter
{
    private static readonly Brush DefaultNegativeBrush = new SolidColorBrush(Colors.Red);
    private static readonly Brush DefaultPositiveBrush = new SolidColorBrush(Colors.Green);
    private static readonly Brush DefaultZeroBrush = new SolidColorBrush(Colors.Green);

    static SignToBrushConverter()
    {
        DefaultNegativeBrush.Freeze();
        DefaultPositiveBrush.Freeze();
        DefaultZeroBrush.Freeze();
    }

    public Brush NegativeBrush { get; set; }
    public Brush PositiveBrush { get; set; }
    public Brush ZeroBrush { get; set; }

    public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
    {
        if (!IsSupportedType(value)) return DependencyProperty.UnsetValue;

        double doubleValue = System.Convert.ToDouble(value);

        if (doubleValue < 0d) return NegativeBrush ?? DefaultNegativeBrush;
        if (doubleValue > 0d) return PositiveBrush ?? DefaultPositiveBrush;

        return ZeroBrush ?? DefaultZeroBrush;
    }

    private static bool IsSupportedType(object value)
    {
        return value is int || value is double || value is byte || value is long ||
               value is float || value is uint || value is short || value is sbyte || 
               value is ushort || value is ulong || value is decimal;
    }

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

用法：

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

<TextBlock Text="{Binding Path=ActualValue, StringFormat='({0:+0.0;-0.0})'}" 
           Foreground="{Binding ActualValue, Converter={StaticResource SignToBrushConverter}}" />

或者，如果您想覆盖默认颜色：

<local:SignToBrushConverter x:Key="SignToBrushConverter" NegativeBrush="Purple" PositiveBrush="DodgerBlue" ZeroBrush="Chocolate" />