GraphVizDocumentToImageConverter.cs

using System;
using System.IO;
using System.Threading.Tasks;
using Waher.Content;
using Waher.Content.Images;
using Waher.Runtime.Inventory;
using Waher.Script;
 
namespace Waher.Content.Markdown.GraphViz
{
    public class GraphVizDocumentToImageConverter : IContentConverter
    {
        public GraphVizDocumentToImageConverter()
        {
        }
 
        public string[] FromContentTypes => new string[] { GraphVizCodec.DefaultContentType };
 
        public virtual string[] ToContentTypes
        {
            get
            {
                return new string[]
                {
                    ImageCodec.ContentTypePng,
                    ImageCodec.ContentTypeSvg
                };
            }
        }
 
        public virtual Grade ConversionGrade => Grade.Excellent;
 
        public async Task<bool> ConvertAsync(ConversionState State)
        {
            string GraphDescription;
 
            using (StreamReader rd = new StreamReader(State.From))
            {
                GraphDescription = rd.ReadToEnd();
            }
 
            string s = State.ToContentType;
            int i;
 
            i = s.IndexOf(';');
            if (i > 0)
                s = s.Substring(0, i);
 
            bool Png = string.Compare(s, ImageCodec.ContentTypePng, true) == 0;
            bool Svg = string.Compare(s, ImageCodec.ContentTypeSvg, true) == 0;
 
            if (!(State.PossibleContentTypes is null))
            {
                foreach (string ContentType in State.PossibleContentTypes)
                {
                    s = ContentType;
                    i = s.IndexOf(';');
                    if (i > 0)
                        s = s.Substring(0, i);
 
                    Png |= string.Compare(s, ImageCodec.ContentTypePng, true) == 0;
                    Svg |= string.Compare(s, ImageCodec.ContentTypeSvg, true) == 0;
                }
            }
 
            string Language;
 
            if (string.IsNullOrEmpty(State.FromFileName))
                Language = "dot";
            else
            {
                Language = Path.GetExtension(State.FromFileName).ToLower();
                if (Language.StartsWith("."))
                    Language = Language.Substring(1);
 
                switch (Language)
                {
                    case "dot":
                    case "neato":
                    case "fdp":
                    case "sfdp":
                    case "twopi":
                    case "circo":
                        break;
 
                    default:
                        Language = "dot";
                        break;
                }
            }
 
            Variables Variables = new Variables();
            GraphInfo Graph;
 
            if (Svg)
            {
                Graph = await GraphViz.GetFileName(Language, GraphDescription, ResultType.Svg, true, Variables);
                State.ToContentType = ImageCodec.ContentTypeSvg;
            }
            else if (Png)
            {
                Graph = await GraphViz.GetFileName(Language, GraphDescription, ResultType.Png, true, Variables);
                State.ToContentType = ImageCodec.ContentTypePng;
            }
            else
                throw new Exception("Unable to convert document from " + State.FromContentType + " to " + State.ToContentType);
 
            byte[] Data = await Resources.ReadAllBytesAsync(Graph.FileName);
 
            await State.To.WriteAsync(Data, 0, Data.Length);
 
            return false;
        }
 
    }
}