How to convert PPTX to PDF in ASP.NET Core?

        /// <summary>
        /// Converts the PowerPoint presentation (PPTX) to PDF document
        /// </summary>
        [AcceptVerbs("Post")]
        public HttpResponseMessage ConvertToPdf()
        {
            HttpResponseMessage httpResponseMessage;
            using (Stream stream = Request.Content.ReadAsStreamAsync().Result)
            {
                try
                {
                    //Opens the PowerPoint presentation (PPTX) from stream
                    using (IPresentation presentation = Presentation.Open(stream))
                    {
                        //Initializes the ChartToImageConverter for converting charts during PPTX to PDF conversion
                        presentation.ChartToImageConverter = new ChartToImageConverter
                        {
                            ScalingMode = Syncfusion.OfficeChart.ScalingMode.Best
                        };
 
                        //Creates an instance of the PresentationToPdfConverterSettings
                        PresentationToPdfConverterSettings settings = new PresentationToPdfConverterSettings
                        {
                            ShowHiddenSlides = true
                        };
                        //Converts PowerPoint presentation (PPTX) into PDF document
                        PdfDocument pdfDocument = PresentationToPdfConverter.Convert(presentation, settings);
                        //Adds watermark at top left corner of first page in the generated PDF document to denote that it is generated using demo web service
                        //To remove this watermark, comment or delete the codes within below "if" statement
                        if (pdfDocument.Pages.Count > 0)
                        {
                            PdfPage pdfPage = pdfDocument.Pages[0];
                            //Create PDF font and PDF font style using Font
                            Font font = new Font("Times New Roman", 12f, FontStyle.Regular);
                            PdfFont pdfFont = new PdfTrueTypeFont(font, false);
                            //Create a new PDF brush to draw the rectangle
                            PdfBrush pdfBrush = new PdfSolidBrush(Color.White);
                            //Draw rectangle in the current page
                            pdfPage.Graphics.DrawRectangle(pdfBrush, 0f, 0f, 228f, 20.65f);
                            //Create a new brush to draw the text
                            pdfBrush = new PdfSolidBrush(Color.Red);
                            //Draw text in the current page
                            pdfPage.Graphics.DrawString("Created by Syncfusion – Presentation library", pdfFont,
                                pdfBrush, 6f, 4f);
                        }
                        //Saves the PDF document to response stream
                        MemoryStream memoryStream = new MemoryStream();
                        pdfDocument.Save(memoryStream);
                        memoryStream.Position = 0;
                        httpResponseMessage = new HttpResponseMessage(HttpStatusCode.OK)
                        {
                            Content = new StreamContent(memoryStream)
                        };
                        pdfDocument.Dispose();
                    }
                }
                catch
                {
                    httpResponseMessage = new HttpResponseMessage(HttpStatusCode.ExpectationFailed);
                }
            }
            return httpResponseMessage;
        }

        public async System.Threading.Tasks.Task<ActionResult> Index(string button)
        {
            if (button == null)
                return View();
 
            //Gets file path for template document
            string rootPath = _hostingEnvironment.WebRootPath;            
            FileStream fileStream = new FileStream(rootPath + "/PPTX/TemplateFile.pptx", FileMode.Open);
            //Open the input presentation file
            IPresentation presentation = Presentation.Open(fileStream);
            fileStream.Dispose();
 
            //Saves a presentation into stream and close the presentation instance
            MemoryStream inputStream = new MemoryStream();
            presentation.Save(inputStream);
            inputStream.Position = 0;
            presentation.Close();
            #region Service approach to send presentation document as stream and gets resultant converted PDF from it.
            HttpClient client = new HttpClient();
            //Gets Uri 
            string requestUri = "http://js.syncfusion.com/demos/ioservices/api/powerpoint/converttopdf";
            //Posts input presentation document to service and gets resultant PDF as content of HttpResponseMessage
            HttpResponseMessage response = null;
            try
            {
                response = await client.PostAsync(requestUri, new StreamContent(inputStream));
                //Dispose the input stream and client instances
                inputStream.Dispose();
                client.Dispose();
            }
            catch (Exception ex)
            {
                //Gets exception here
            }
            MemoryStream outputStream = null;
            //Gets PDF from content stream if service got success
            if (response.IsSuccessStatusCode)
            {
                var responseHeaders = response.Headers;
                outputStream = new MemoryStream(await response.Content.ReadAsByteArrayAsync());
                outputStream.Position = 0;
                //Dispose the response instance
                response.Dispose();
            }
            #endregion
 
            return File(outputStream, "application/pdf", "Sample.pdf");
        }

string requestUri = "http://js.syncfusion.com/demos/ioservices/api/powerpoint/converttopdf";