comic-img-compress/ImageExtractor.cs

using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.Drawing;
using System.IO;
using System.Runtime.ConstrainedExecution;
using ikvm.extensions;
using Imazen.WebP;

using iMGcompress_core;

using iTextSharp.text.pdf;
using iTextSharp.text.pdf.parser;

using SharpCompress.Archives;
using SharpCompress.Archives.Zip;
using SharpCompress.Common;

using Path = System.IO.Path;

namespace ComicCompressor
{
    /// <summary>
    /// Helper lass to dump all images from a PDF into separate files
    /// </summary>
    public class ImageExtractor : IRenderListener
    {
        int _currentPage = 1;
        int _imageCount = 0;
        readonly string _outputFilePrefix = "";
        //readonly string _outputFolder;
        //readonly bool _overwriteExistingFiles;
        private bool Cover = true;
        private Logger Logger { get; set; }
        SimpleEncoder encoder = new SimpleEncoder();
        public int Quality { get; set; } = 75;
        private List<Stream> imageStreams = null;
        public ZipArchive output = null;

        public ImageExtractor(Logger logger)
        {
            Logger = logger;
            //_outputFilePrefix = outputFilePrefix;
            //_outputFolder = outputFolder;
            //_overwriteExistingFiles = overwriteExistingFiles;
        }
        public int GetPlace(int value, int place)
        {
            return ((value % (place * 10)) - (value % place)) / place;
        }
        /// <summary>
        /// Extract all images from a PDF file
        /// </summary>
        /// <param name="pdfPath">Full path and file name of PDF file</param>
        /// <param name="outputFilePrefix">Basic name of exported files. If null then uses same name as PDF file.</param>
        /// <param name="outputFolder">Where to save images. If null or empty then uses same folder as PDF file.</param>
        /// <param name="overwriteExistingFiles">True to overwrite existing image files, false to skip past them</param>
        /// <returns>Count of number of images extracted.</returns>
        public int ExtractImagesFromFile(string pdfPath, string outputFolder, int quality = 75)
        {
            // Handle setting of any default values
            //outputFilePrefix = outputFilePrefix ?? Path.GetFileNameWithoutExtension(pdfPath);
            //outputFolder = String.IsNullOrEmpty(outputFolder) ? Path.GetDirectoryName(pdfPath) : outputFolder;

            quality = quality;

            Stopwatch sw = Stopwatch.StartNew();
            using (var pdfReader = new PdfReader(pdfPath))
            {
                Logger.Log($"Processing[{pdfReader.NumberOfPages}]: " + pdfPath, LogLevel.Verbose);

                if (pdfReader.IsEncrypted())
                    throw new ApplicationException(pdfPath + " is encrypted.");

                var pdfParser = new PdfReaderContentParser(pdfReader);

                output = ZipArchive.Create();
                {
                    imageStreams = new List<Stream>();
                    int count = 0;
                    Cover = true;
                    while (_currentPage <= pdfReader.NumberOfPages)
                    {
                        pdfParser.ProcessContent(_currentPage, this);

                        _currentPage++;
                        count++;
                        if (count % 10 == 0)
                        {
                            string digit = GetPlace(count, 10).ToString();
                            Logger.Log(digit, LogLevel.Verbose, false);
                        }
                    }


                    Directory.CreateDirectory(Path.GetDirectoryName(outputFolder));

                    output.SaveTo(outputFolder, CompressionType.Deflate);

                    //output.SaveTo(outputPath, CompressionType.None);

                    imageStreams.ForEach(i => i.Dispose());
                }
                output.Dispose();
                int nop = pdfReader.NumberOfPages;
                if (nop == 0) nop = 1;
                long elapsed = sw.ElapsedMilliseconds;
                //Logger.Log($"\r\nFinished({save.ToString("0.##")}): " + pdfPath, LogLevel.Verbose);
                Logger.Log($"\r\nFinished({0.ToString("0.##")} [{elapsed}][{elapsed / nop}]): " + pdfPath, LogLevel.Verbose);

            }

            return _imageCount;
        }
        private Bitmap ChangePixelFormat(Bitmap orig, System.Drawing.Imaging.PixelFormat format = System.Drawing.Imaging.PixelFormat.Format24bppRgb)
        {
            Bitmap clone = new Bitmap(orig.Width, orig.Height, format);

            using (Graphics gr = Graphics.FromImage(clone))
            {
                gr.DrawImage(orig, new Rectangle(0, 0, clone.Width, clone.Height));
            }

            return clone;

        }

        #region Implementation of IRenderListener

        public void BeginTextBlock()
        {
        }

        public void EndTextBlock()
        {
        }

        public void RenderText(TextRenderInfo renderInfo)
        {
            var text = renderInfo.GetText();
        }

        public void RenderImage(ImageRenderInfo renderInfo)
        {
            try
            {
                var type = renderInfo.GetType();
                var str = renderInfo.toString();
                //var ftype = renderInfo.GetFileType();
                var imageObject = renderInfo.GetImage();

                //var imageFileName = String.Format("{0}_{1}_{2}.{3}", _outputFilePrefix, _currentPage, _imageCount,
                //    imageObject.GetFileType());
                var imageFileName = String.Format($"{_imageCount.ToString("0000")}");
                //var imagePath = Path.Combine(_outputFolder, imageFileName);

                //if (_overwriteExistingFiles || !File.Exists(imagePath))
                {
                    var imageRawBytes = imageObject.GetImageAsBytes();
                    var image = imageObject.GetDrawingImage();

                    //File.WriteAllBytes(imagePath, imageRawBytes);
                    if (image.Width < 512 || image.Height < 512)
                        return;

                    if (image.PixelFormat != System.Drawing.Imaging.PixelFormat.Format24bppRgb)
                    {
                        var newBits = ChangePixelFormat((Bitmap)image);
                        image.Dispose();
                        image = newBits;
                    }

                    var ms = new MemoryStream();
                    encoder.Encode((Bitmap)image, ms, Quality);
                    if (!Cover && ms.Length < imageRawBytes.Length)
                    {
                        imageStreams.Add(ms);
                        output.AddEntry(imageFileName + ".webp", ms);
                        Logger.Log(".", LogLevel.Verbose, false);
                    }
                    else
                    {
                        var mso = new MemoryStream();
                        mso.Write(imageRawBytes);
                        output.AddEntry(imageFileName + imageObject.GetFileType(), mso);
                        Logger.Log(Cover ? "C" : "=", LogLevel.Verbose, false);
                        Cover = false;
                    }
                }

                // Subtle: Always increment even if file is not written. This ensures consistency should only some
                //   of a PDF file's images actually exist.
                _imageCount++;
            }
            catch (Exception e)
            {
                Console.WriteLine(e);
                throw;
            }

        }

        #endregion // Implementation of IRenderListener

    }
}