Dart Requires Chilkat v11.7.0+

Shrink a PDF Losslessly

See more PDF Optimization Examples

Demonstrates the "optimize" operation with the default options, which is the lossless preset: nothing is resampled, recoloured or thrown away, so every page looks exactly as it did and all the text is still there. The changes are kept in memory until WriteFile (or WriteBd) is called. Note that the real saving is "fileSize" minus the size of the file that was written, not "bytesSaved": the rewrite also packs objects into object streams and writes a compact cross-reference stream, which belongs to no option. Dart

import 'package:chilkat/chilkat.dart';

void main() {
  // This example requires the Chilkat API to have been previously unlocked.
  // See Global Unlock Sample for sample code.

  // The PDF used in this example is available at grand_canyon_hiking_guide.pdf

  final pdf = CkPdf();
  try {
    pdf.loadFile('qa_data/pdf/grand_canyon_hiking_guide.pdf');
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    return;
  }

  // An empty JSON means the default options: every lossless optimization, object streams generated,
  // old revisions dropped, deflate level 9.
  final json = CkJsonObject();
  final jsonOut = CkJsonObject();
  try {
    pdf.optimize('optimize', json, jsonOut);
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    return;
  }

  // Nothing has been written yet.  WriteFile (or WriteBd) produces the optimized PDF.
  try {
    pdf.writeFile('qa_output/grand_canyon_optimized.pdf');
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    return;
  }

  final fac = CkFileAccess();
  final sizeBefore = jsonOut.intOf('fileSize');
  final sizeAfter = fac.fileSize('qa_output/grand_canyon_optimized.pdf');

  print('before: $sizeBefore');
  print('after:  $sizeAfter');
  print('saved:  ${sizeBefore - sizeAfter}');

  // What the options themselves account for.  This is smaller than the real saving above, because the
  // rewrite's own gains (object streams, the cross-reference stream, the old sections left behind)
  // belong to no single option.
  print('bytesSaved (options only): ${jsonOut.intOf('bytesSaved')}');
}