FrameJsonConverter.cs

using Gondwana.Drawing.Tilesheets;
using Newtonsoft.Json;
using Newtonsoft.Json.Linq;
 
namespace Gondwana.Drawing;

internal sealed class FrameJsonConverter : JsonConverter<Frame>
{
    public override void WriteJson(JsonWriter writer,
                                   Frame value,
                                   JsonSerializer serializer)
    {
        if (value.Tilesheet is null)
        {
            writer.WriteNull();
            return;
        }
 
        writer.WriteStartObject();
 
        writer.WritePropertyName("tilesheet");
        writer.WriteValue(value.Tilesheet.Name);
 
        writer.WritePropertyName("regionName");
        writer.WriteValue(value.RegionName);
 
        writer.WritePropertyName("xTile");
        writer.WriteValue(value.XTile);
 
        writer.WritePropertyName("yTile");
        writer.WriteValue(value.YTile);
 
        writer.WriteEndObject();
    }

    public override Frame ReadJson(JsonReader reader,
                                   Type objectType,
                                   Frame existingValue,
                                   bool hasExistingValue,
                                   JsonSerializer serializer)
    {
        if (reader.TokenType == JsonToken.Null)
            return default;
 
        var obj = JObject.Load(reader);
 
        var tilesheetName = obj.Value<string>("tilesheet");
        var regionName = obj.Value<string>("regionName") ?? TilesheetRegion.DefaultRegionName;
 
        var xTile = obj.Value<int?>("xTile") ?? 0;
        var yTile = obj.Value<int?>("yTile") ?? 0;
 
        if (string.IsNullOrWhiteSpace(tilesheetName))
            throw new JsonSerializationException("Frame is missing required tilesheet name.");
 
        var tilesheet = TilesheetRegistry.Instance.GetOrNull(tilesheetName);
 
        if (tilesheet is null)
        {
            throw new JsonSerializationException(
                $"Could not resolve Tilesheet '{tilesheetName}' while deserializing Frame.");
        }
 
        return new Frame(tilesheet, regionName, xTile, yTile);
    }
}