Conversion

import com.spire.xls.FileFormat;
import com.spire.xls.Workbook;
import com.spire.xls.core.spreadsheet.HTMLOptions;

import javax.imageio.ImageIO;
import java.awt.*;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;


public class ConvertDemo {

   public void convertDemo(String filePath, String convertTo, String resultFileName) throws IOException {
       Workbook workbook = new Workbook();
       workbook.loadFromFile(filePath);
       ConvertFormat(workbook,convertTo,resultFileName);

   }
    private void ConvertFormat(Workbook workbook, String convertTo, String resultFileName) throws IOException {
        switch (convertTo){
            case "PDF":
                workbook.getConverterSetting().setSheetFitToPage(true);
                workbook.saveToFile(resultFileName + ".pdf", FileFormat.PDF);
                break;
            case "IMAGE":
                BufferedImage[] images = (BufferedImage[]) new Image[workbook.getWorksheets().size()];
                for (int i = 0; i < workbook.getWorksheets().size();i++){
                    images[i] = workbook.saveAsImage(i,300,300);
                }
                if (images != null && images.length > 0){
                    if (images.length == 1){
                        ImageIO.write(images[0],".PNG", new File(resultFileName+".png"));
                    }
                }else {
                    for (int j = 0; j < images.length;j++){
                        String fileName = String.format("image-{0}.png",j);
                        ImageIO.write(images[j],".PNG",new File(fileName));
                    }
                }
                    break;
            case "HTML":
                for (int i = 0; i < workbook.getWorksheets().size(); i++) {
                    HTMLOptions options = new HTMLOptions();
                    options.setImageEmbedded(true);
                    String htmlPath = String.format(resultFileName+"-{0}.html",i++);
                    workbook.getWorksheets().get(i).saveToHtml(htmlPath,options);
                }
                break;
            case "TIFF":
                workbook.saveToTiff(resultFileName+".tiff");
                break;
            case "XPS":
                workbook.saveToFile(resultFileName+".xps",FileFormat.XPS);
                break;
        }
    }
}

using System;
using Spire.Xls;
using System.Drawing;
using System.Drawing.Imaging;

namespace DemoOnlineCode
{
    class Convertors
    {
        public void demoConvert(String filePath, string format, string resultFileName)
        {
            Workbook book = new Workbook();
            book.LoadFromFile(filePath);
            ConvertFormat(book, format, resultFileName);
        }
        private void ConvertFormat(Workbook workbook, string format, string resultFileName)
        {
            switch (format)
            {
                case "PDF":
                    workbook.ConverterSetting.SheetFitToPage = true;
                    workbook.SaveToFile(resultFileName + ".pdf", Spire.Xls.FileFormat.PDF);
                    break;
                case "IMAGE":
                    Image[] images = new Image[workbook.Worksheets.Count];
                    for (int i = 0; i < workbook.Worksheets.Count; i++)
                    {
                        images[i] = workbook.SaveAsImage(i, 300, 300);
                    }
                    if (images != null && images.Length > 0)
                    {
                        if (images.Length == 1)
                        {
                            images[0].Save(resultFileName + ".png", ImageFormat.Png);
                        }
                        else
                        {
                            for (int i = 0; i < images.Length; i++)
                            {
                                String fileName = String.Format("{0}-Image-{1}.png", resultFileName, i);
                                images[i].Save(fileName, ImageFormat.Png);
                            }
                        }
                    }
                    break;

                case "HTML":
                    for (int i = 0; i < workbook.Worksheets.Count; i++)
                    {
                        Worksheet sheet = workbook.Worksheets[i];
                        string htmlPath = string.Format(resultFileName + "-{0}.html", i++);
                        sheet.SaveToHtml(htmlPath);
                    }
                    break;
                case "TIFF":
                    JoinTiffImages(ToImage(workbook), resultFileName + ".tiff", EncoderValue.CompressionLZW);
                    break;
                case "XPS":
                    workbook.SaveToFile(resultFileName+".xps",FileFormat.XPS);
                    break;
            }
        }
        private static Image[] ToImage(Workbook workbook)
        {
            //Get the worksheet count of workbook
            int workSheetNo = workbook.Worksheets.Count;

            //Create an array
            Image[] images = new Image[workSheetNo];

            //Save worksheet to image and add the array
            for (int i = 0; i < workSheetNo; i++)
            {
                Worksheet workSheet = workbook.Worksheets[i];
                string output = string.Format("result{0}.jpg", i + 1);
                workSheet.SaveToImage(output);
                Image image = Image.FromFile(output);
                images[i] = image;
            }
            return images;
        }

        private static ImageCodecInfo GetEncoderInfo(string mimeType)
        {
            ImageCodecInfo[] encoders = ImageCodecInfo.GetImageEncoders();
            for (int j = 0; j < encoders.Length; j++)
            {
                if (encoders[j].MimeType == mimeType)
                    return encoders[j];
            }
            throw new Exception(mimeType + " mime type not found in ImageCodecInfo");
        }

        private void JoinTiffImages(Image[] images, string outFile, EncoderValue compressEncoder)
        {
            //Use the save encoder
            Encoder enc = Encoder.SaveFlag;
            EncoderParameters ep = new EncoderParameters(2);
            ep.Param[0] = new EncoderParameter(enc, (long)EncoderValue.MultiFrame);
            ep.Param[1] = new EncoderParameter(Encoder.Compression, (long)compressEncoder);
            Image pages = images[0];
            int frame = 0;
            ImageCodecInfo info = GetEncoderInfo("image/tiff");
            foreach (Image img in images)
            {
                if (frame == 0)
                {
                    pages = img;
                    //save the first frame
                    pages.Save(outFile, info, ep);
                }

                else
                {
                    //save the intermediate frames
                    ep.Param[0] = new EncoderParameter(enc, (long)EncoderValue.FrameDimensionPage);

                    pages.SaveAdd(img, ep);
                }
                if (frame == images.Length - 1)
                {
                    //flush and close.
                    ep.Param[0] = new EncoderParameter(enc, (long)EncoderValue.Flush);
                    pages.SaveAdd(ep);
                }
                frame++;
            }
        }
    }
}