c# - 使用 JsonConverter 序列化/反序列化各种 `Brush` 类型

Question

因此，在阅读了有关 Json.NET 无法(反)序列化 Brush 类型的各种其他问题和答案后，很明显我需要自己的 JsonConverter。然而，我被卡住的地方是我正在使用中间对象来处理数据，因为它是(反)序列化的，并且由于根据画笔类型有各种类型的对象，我假设我也需要将类型信息存储在 Json 中，但是使用 [JsonProperty( TypeNameHandling = TypeNameHandling.All )] 不起作用。

我的转换器:

public class BrushJsonConverter : JsonConverter
{
    public override void WriteJson(JsonWriter writer, object value, JsonSerializer serializer)
    {
        object SerializableBrush = null;
        if (value is SolidColorBrush)
            SerializableBrush = new SerializableColorBrush(value as SolidColorBrush);

        var jo = JObject.FromObject(SerializableBrush);
        jo.WriteTo(writer);
    }

    public override object ReadJson(JsonReader reader, Type objectType, object existingValue,
        JsonSerializer serializer)
    {
        // Load JObject from stream
        var jObject = JObject.Load(reader);

        dynamic SerializableBrush = JsonConvert.DeserializeObject(jObject.ToString());

        if (SerializableBrush is SerializableColorBrush)
            return (SerializableBrush as SerializableColorBrush).ToBrush();
        else if (SerializableBrush is SerializableImageBrush)
            return (SerializableBrush as SerializableImageBrush).ToBrush();
        else return null;

    }

    public override bool CanConvert(Type objectType)
    {
        return typeof(Brush).IsAssignableFrom(objectType);
    }
}

我的中介对象:

class SerializableColorBrush
{
    public Color Color{ get; set; }

    public SerializableColorBrush(SolidColorBrush Brush)
    {
        this.Color = Brush.Color;
    }

    public SolidColorBrush ToBrush()
    {
        SolidColorBrush brush = new SolidColorBrush(this.Color);
        return brush;
    }
}
class SerializableImageBrush
{
    public ImageSource ImageSource { get; set; }
    public TileMode TileMode { get; set; }
    public Stretch Stretch { get; set; }
    public AlignmentX AlignmentX { get; set; }
    public AlignmentY AlignmentY { get; set; }

    public SerializableImageBrush(ImageBrush Brush)
    {
        this.ImageSource = Brush.ImageSource;
        this.TileMode = Brush.TileMode;
        this.Stretch = Brush.Stretch;
        this.AlignmentX = Brush.AlignmentX;
        this.AlignmentY = Brush.AlignmentY;
    }

    public ImageBrush ToBrush()
    {
        ImageBrush brush = new ImageBrush();
        brush.ImageSource = ImageSource;
        brush.TileMode = TileMode;
        brush.Stretch = Stretch;
        brush.AlignmentX = AlignmentX;
        brush.AlignmentY = AlignmentY;
        return brush;
    }
}

要序列化的示例属性:

    private Brush _WindowBG = SystemColors.AppWorkspaceBrush;
    [JsonConverter(typeof(BrushJsonConverter))]
    [JsonProperty( TypeNameHandling = TypeNameHandling.All )]
    public Brush WindowBG { get { return _WindowBG; } set { if (value != _WindowBG) { _WindowBG = value; PropertyChanged?.Invoke(this, new PropertyChangedEventArgs("WindowBG")); } } }

我哪里误入歧途了？我什至用这种方法朝着正确的方向前进吗？

最终结果是我正在尝试将我的应用程序的主题数据存储到 json 中，并将各种画笔设置为颜色、图像或渐变(尚未包括在内)。

Answer 1

最终选择了不同的路线，恕我直言，这种实现方式更加简洁。

保留了曾经是我的中介对象的对象，但它们现在是我实际使用的存储数据的对象，并且它们(为了便于使用)继承了一个基类；

public class SerializableBrush
{
    public virtual Brush ToBrush()
    {
        return null;
    }
}

public class SerializableColorBrush : SerializableBrush
{
    public Color Color{ get; set; }

    public SerializableColorBrush(SolidColorBrush Brush)
    {
        this.Color = Brush.Color;
    }

    public override Brush ToBrush()
    {
        SolidColorBrush brush = new SolidColorBrush(this.Color);
        return brush;
    }
}
public class SerializableImageBrush : SerializableBrush
{
    public ImageSource ImageSource { get; set; }
    public TileMode TileMode { get; set; }
    public Stretch Stretch { get; set; }
    public AlignmentX AlignmentX { get; set; }
    public AlignmentY AlignmentY { get; set; }

    public SerializableImageBrush(ImageBrush Brush)
    {
        this.ImageSource = Brush.ImageSource;
        this.TileMode = Brush.TileMode;
        this.Stretch = Brush.Stretch;
        this.AlignmentX = Brush.AlignmentX;
        this.AlignmentY = Brush.AlignmentY;
    }

    public override Brush ToBrush()
    {
        ImageBrush brush = new ImageBrush();
        brush.ImageSource = ImageSource;
        brush.TileMode = TileMode;
        brush.Stretch = Stretch;
        brush.AlignmentX = AlignmentX;
        brush.AlignmentY = AlignmentY;
        return brush;
    }
}

然后，我没有将对象直接绑定(bind)到 XAML 中的画笔，而是创建了一个转换器，将我的自定义通用对象转换为画笔(这是基类使事情变得非常简单的地方)；

public class SerializableBrushToBrush : IValueConverter
{
    public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
    {
        return (value as Config.SerializableBrush).ToBrush();
    }

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

当然，我存储画笔信息的模板类需要使用我的新类型，我还添加了一个 OnDeserialized 回调，因为如果我在主窗口显示后填充 Json，我的模板将不会显示；

public class Template : INotifyPropertyChanged
{
    public event PropertyChangedEventHandler PropertyChanged;

    private SerializableBrush _WindowBG = new SerializableColorBrush(SystemColors.AppWorkspaceBrush);
    [JsonProperty(TypeNameHandling = TypeNameHandling.All)]
    public SerializableBrush WindowBG { get { return _WindowBG; } set { if (value != _WindowBG) { _WindowBG = value; PropertyChanged?.Invoke(this, new PropertyChangedEventArgs("WindowBG")); } } }

    [OnDeserialized]
    internal void OnDeserializedMethod(StreamingContext context)
    {
        PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(string.Empty));
    }

}

当然最后我的窗口需要使用新的转换器；

<Window.Resources>
    <local:SerializableBrushToBrush x:Key="SerializableBrushToBrush"/>
</Window.Resources>
<Window.Background>
    <Binding Converter="{StaticResource SerializableBrushToBrush}" Path="Template.WindowBG" Source="{x:Static config:Global.store}"/>
</Window.Background>

现在我的 Json 看起来漂亮干净而且易于操作

  "Template": {
    "WindowBG": {
      "$type": "Config.SerializableImageBrush, Config",
      "ImageSource": "C:\\Users\\jhebb\\Pictures\\20150805_150241.jpg",
      "TileMode": 0,
      "Stretch": 1,
      "AlignmentX": 1,
      "AlignmentY": 1
    },
    "WindowFG": {
      "$type": "Config.SerializableColorBrush, Config",
      "Color": "#FF000000"
    },
    "DeviceBarBG": {
      "$type": "Config.SerializableColorBrush, Config",
      "Color": "#FFA0A0A0"
    },
    "DeviceBarFG": {
      "$type": "Config.SerializableColorBrush, Config",
      "Color": "#FF000000"
    },
    "WorkspaceBG": {
      "$type": "Config.SerializableColorBrush, Config",
      "Color": "#FFFFFFFF"
    },
    "MainTabFG": {
      "$type": "Config.SerializableColorBrush, Config",
      "Color": "#FF000000"
    },
    "MenuBG": {
      "$type": "Config.SerializableColorBrush, Config",
      "Color": "#FFF0F0F0"
    },
    "MenuFG": {
      "$type": "Config.SerializableColorBrush, Config",
      "Color": "#FF000000"
    }
  }