//// This code is part of Document Solutions for PDF .NET demos.// Copyright (c) MESCIUS inc. All rights reserved.//using System;using System.IO;using System.Drawing;using System.Collections.Generic;using GrapeCity.Documents.Pdf;using GrapeCity.Documents.Imaging;using GrapeCity.Documents.Drawing;
namespace DsPdfWeb.Demos{    // This example shows how to convert an arbitrary PDF to a multi-frame TIFF    // in which each frame corresponds to a single PDF page, converting full color    // original pages to grayscale images with an arbitrary target resolution    // (in the sample code the resolution is set to 200 dpi).    //    // Note that while the code in this example uses some DsImaging features,    // it does not need a DsImaging license to work without issues.    // See PdfToTiffDsImaging for an example that does the same conversion faster,    // but does require a valid DsImaging license.    //    // In order to seamlessly build this sample into the demo site framework,    // the generated TIFF is then converted back into a PDF. In a real life scenario    // you can just use the code that generates the TIFF directly.    public class PdfToGrayscaleTiff    {        public int CreatePDF(Stream stream)        {            // Arbitrary target DPI for the generated TIFF, adjust as needed:            const int targetDPI = 200;
            var inputDoc = new GcPdfDocument();            using var fs = File.OpenRead(Path.Combine("Resources", "PDFs", "SlidePages.pdf"));            inputDoc.Load(fs);
            using var ms = new MemoryStream();            using var bmp = new GcBitmap();            // NOTE: to produce a TIFF disk file, you would create a GcTiffWriter            // with the file path as the parameter. But due to the demo browser requirements,            // we create a GcTiffWriter on a memory stream instead:            // using var tiffWriter = new GcTiffWriter("result.tiff");            using var msTiff = new MemoryStream();            using (var tiffWriter = new GcTiffWriter(msTiff))            {                foreach (var p in inputDoc.Pages)                {                    // Save each PDF page as PNG with target resolution:                    ms.Position = 0;                    p.SaveAsPng(ms, new SaveAsImageOptions { Resolution = targetDPI });                    ms.Position = 0;                    bmp.Load(ms);                    // Load the PNG into GcBitmap, apply in-place grayscale effect,                    // convert to grayscale bitmap and append it to the TIFF:                    bmp.ApplyEffect(GrayscaleEffect.Get());                    using var gbmp = bmp.ToGrayscaleBitmap();                    tiffWriter.AppendFrame(gbmp);                }            }            // At this point tiffWriter has the newly created TIFF. If it was created on            // a disk file, that file would contain the TIFF when tiffWriter is disposed.            //            // To use this sample in the demo browser, we have to convert the TIFF            // back to a PDF that is returned to the controller.            msTiff.Position = 0;            var doc = new GcPdfDocument();            using var tiffReader = new GcTiffReader(msTiff);            List<IDisposable> disposables = new List<IDisposable>();            foreach (var tp in tiffReader.Frames)            {                var img = tp.ToImage(ImageBinding.InMemoryData);                var p = doc.Pages.Add(new SizeF(img.Width / img.HorizontalResolution * 72, img.Height / img.VerticalResolution * 72));                p.Graphics.DrawImage(img, p.Bounds, null, ImageAlign.Default);                disposables.Add(img);            }            // Save the PDF:            doc.Save(stream);            // We can only dispose images after saving the PDF:            disposables.ForEach(d_ => d_.Dispose());            return doc.Pages.Count;        }    }}