// 完毕:
using System;
using System.IO;
using System.Drawing;
using System.Collections.Generic;
using GrapeCity.Documents.Pdf;
using GrapeCity.Documents.Pdf.Annotations;
using GrapeCity.Documents.Text;
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;
}
}
}