Show thumbnails of XPS documents

/*
 Copyright 2010 Pravesh Soni
 */

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.ComponentModel;
using System.IO;
using System.Windows.Documents;
using System.Windows.Media.Imaging;
using System.Windows.Xps.Packaging;
using System.Windows.Media;

namespace XPS2Image
{
    /// <summary>
    /// Imageformat
    /// </summary>
    public enum OutputFormat
    {
        Jpeg,
        Png,
        Gif
    }

    /// <summary>
    /// Image Quality
    /// </summary>
    public enum OutputQuality
    {
        Low,
        Normal,
        Good,
        Super
    }

    /// <summary>
    /// Provides methods for converting XPS document in to various image format
    /// </summary>
    public class XpsImage
    {
        private BitmapEncoder bitmapEncoder = null;
        /// <summary>
        /// Default constructor
        /// </summary>
        public XpsImage()
        {
        }

        /// <summary>
        /// Sets the XPS file to be read
        /// </summary>
        public String XpsFileName { private get; set; }

        /// <summary>
        /// Gets or Sets the image format for thumbnail
        /// </summary>
        public OutputFormat OutputFormat {get; set; }

        /// <summary>
        /// Gets or Sets the image quality for thumbnail
        /// </summary>
        public OutputQuality OutputQuality { private get; set; }
        
        /// <summary>
        /// Returns the Memory stream of generated thumbnail
        /// </summary>
        public MemoryStream OutputStream { get; private set; }

        /// <summary>
        /// Generate the thumbnail of given document and populates the ThumbnailStream property
        /// </summary>
        public void GenerateThumbnail()
        {
            XpsDocument xpsDocument = new XpsDocument(this.XpsFileName, FileAccess.Read);
            FixedDocumentSequence documentPageSequence = xpsDocument.GetFixedDocumentSequence();
            
            string fileNameWithoutExtension = Path.GetFileNameWithoutExtension(this.XpsFileName);
            string fileExtension = string.Empty;

            switch (this.OutputFormat)
            {
                case OutputFormat.Jpeg:
                    fileExtension = ".jpg";
                    bitmapEncoder = new JpegBitmapEncoder();
                    break;
                case OutputFormat.Png:
                    fileExtension = ".png";
                    bitmapEncoder = new PngBitmapEncoder();
                    break;
                case OutputFormat.Gif:
                    fileExtension = ".gif";
                    bitmapEncoder = new GifBitmapEncoder();
                    break;
                default:
                    fileExtension = ".jpg";
                    bitmapEncoder = new JpegBitmapEncoder();
                    break;
            }
            
            double imageQualityRatio = 1.0;
            switch (this.OutputQuality)
            {
                case OutputQuality.Low:
                    imageQualityRatio /= 2.0;
                    break;

                case OutputQuality.Good:
                    imageQualityRatio *= 2.0;
                    break;

                case OutputQuality.Super:
                    imageQualityRatio *= 3.0;
                    break;
                default:
                    imageQualityRatio *= 1.0;
                    break;
            }

            DocumentPage documentPage = documentPageSequence.DocumentPaginator.GetPage(0);
            RenderTargetBitmap targetBitmap = new RenderTargetBitmap((int)(documentPage.Size.Width * imageQualityRatio), (int)(documentPage.Size.Height * imageQualityRatio), 96.0 * imageQualityRatio, 96.0 * imageQualityRatio, PixelFormats.Pbgra32);
            targetBitmap.Render(documentPage.Visual);
            
            

            bitmapEncoder.Frames.Add(BitmapFrame.Create(targetBitmap));
            string str4 = string.Format("{0}{1}", fileNameWithoutExtension, fileExtension);

            MemoryStream memoryStream = new MemoryStream();
            bitmapEncoder.Save(memoryStream);
            this.OutputStream = memoryStream;
            xpsDocument.Close();
        }


    }
}