SvgHandler.cs

SvgHandler.cs

public class SvgHandler : IHttpHandler
    {
        public void ProcessRequest(HttpContext context)
        {
            var fileName = Path.GetFileName(context.Request.AppRelativeCurrentExecutionFilePath) ?? string.Empty;
            var svgIndex = fileName.LastIndexOf(".svg", StringComparison.InvariantCultureIgnoreCase);
            var classIndex = fileName.IndexOf('.');
            string[] classNames = new string[0];
            string svgPath;

            if (svgIndex != classIndex)
            {
                classNames = fileName.Substring(classIndex, svgIndex - classIndex).Split('.');
                svgPath = context.Server.MapPath(fileName.Substring(0, classIndex) + ".svg");
            }
            else
            {
                svgPath = context.Server.MapPath(fileName);
            }

            context.Response.ContentType = "image/svg+xml";
            context.Response.Cache.SetExpires(DateTime.UtcNow.AddYears(1));
            if (!classNames.Any())
            {
                // Early return if no changes need to be done.
                context.Response.WriteFile(svgPath);
                return;
            }

            var svgDocument = new XmlDocument();
            svgDocument.Load(svgPath);

            if (svgDocument.DocumentElement != null)
            {
                var attributes = svgDocument.DocumentElement.Attributes;
                var classAttribute = attributes["class"];
                if (classAttribute == null)
                {
                    classAttribute = svgDocument.CreateAttribute("class");
                    attributes.Append(classAttribute);
                }

                classAttribute.Value = string.Join(" ", classNames);
            }

            using (var memoryStream = new MemoryStream())
            {
                svgDocument.Save(memoryStream);
                context.Response.BinaryWrite(memoryStream.ToArray());
            }
        }

        public bool IsReusable
        {
            get { return true; }
        }
    }