// 完毕:
using System;
using System.IO;
using System.IO.Compression;
using System.Drawing;
using System.Collections.Generic;
using GrapeCity.Documents.Pdf;
using GrapeCity.Documents.Text;
using GrapeCity.Documents.Common;
namespace DsPdfWeb.Demos
{
// This sample shows how the GcPdfDocument.OptimizeFonts() method can be used
// to reduce the size of a PDF by merging duplicate and removing unused embedded fonts.
//
// This sample extracts the first five pages of a PDF, and then merges those pages
// into a single new document. Because each page has its own set of embedded fonts,
// the created PDF contains redundant font data, resulting in excessive file size.
// The sample records the merged PDF's size, then it runs OptimizeFonts() on that PDF
// and records the size of the optimized PDF. These results are printed into the
// PDF returned by the sample, thus illustrating the effect of running OptimizeFonts().
//
// Note that while in this sample the PDF being optimized is somewhat contrived,
// similar PDFs do appear in real life applications. The OptimizeFonts()
// method may reduce (sometimes significantly) the size of such PDFs.
// Actual results will vary.
//
// See also RemoveDuplicateImages.
public class OptimizeFonts
{
public int CreatePDF(Stream stream)
{
// Create a 5 page non-optimal PDF:
var srcFn = Path.Combine("Resources", "PDFs", "CompleteJavaScriptBook.pdf");
var tmpInput = MakeInputFile(srcFn);
var fiInput = new FileInfo(tmpInput);
// Create a new PDF, load the source PDF into it, and optimize it:
var tmpOutput = Path.GetTempFileName();
var tmpDoc = new GcPdfDocument();
using (var fs = File.OpenRead(tmpInput))
{
tmpDoc.Load(fs);
// By default GcPdfDocument uses CompressionLevel.Fastest when saving a PDF.
// If PDF size is important, we should use optimal compression:
tmpDoc.CompressionLevel = CompressionLevel.Optimal;
tmpDoc.OptimizeFonts();
tmpDoc.Save(tmpOutput);
}
var fiOutput = new FileInfo(tmpOutput);
// Record the input and output file sizes in the resultant PDF:
var doc = new GcPdfDocument();
Common.Util.AddNote(String.Format(
"Using the GcPdfDocument.OptimizeFonts() method reduced the size of a 5-page PDF from {0:N0} to {1:N0} bytes " +
"by merging duplicate and removing unused font data.\n" +
"To reproduce these results locally, download and run this sample. You may also modify the sample code to keep the temporary " +
"input and output files and compare their sizes using a file manager.", fiInput.Length, fiOutput.Length),
doc.NewPage());
doc.Save(stream);
// Clean up:
File.Delete(tmpInput);
File.Delete(tmpOutput);
return doc.Pages.Count;
}
static string MakeInputFile(string inFn)
{
var indoc = new GcPdfDocument();
using var fs = File.OpenRead(inFn);
indoc.Load(fs);
// Create 5 PDFs from the first 5 pages of the source document:
var pageCount = 5;
var docs = new List<GcPdfDocument>(pageCount);
for (int i = 0; i < pageCount; ++i)
{
var outdoc = new GcPdfDocument();
outdoc.MergeWithDocument(indoc, new MergeDocumentOptions() { PagesRange = new OutputRange(i + 1, i + 1) });
docs.Add(outdoc);
}
// Merge the PDFs into a single document:
var doc = new GcPdfDocument();
foreach (var d in docs)
doc.MergeWithDocument(d);
// Save the resultant PDF in a temp file:
var outFn = Path.GetTempFileName();
doc.Save(outFn);
return outFn;
}
}
}