Dart Requires Chilkat v11.7.0+

Search for Text in a PDF

See more PDF Text Extraction Examples

Demonstrates the "search" operation, which finds every occurrence of a string in a PDF and returns each match with its page number and the text around it. Matching ignores case unless caseSensitive is true. 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 three-page PDF used in this example is available at search_context.pdf

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

  final json = CkJsonObject();
  final jsonOut = CkJsonObject();

  // The string to find.
  json.updateString('query', 'chilkat');

  // The number of characters returned before and after each match.  The default is 40.
  json.updateInt('context', 30);

  try {
    pdf.extractText('search', json, jsonOut);
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    return;
  }

  // "count" is the number of matches.  Each match has the page, the matched text as it appears
  // in the PDF, and the text before and after it.
  print('Matches: ${jsonOut.intOf('count')}');

  var i = 0;
  final countI = jsonOut.sizeOfArray('matches');
  while (i < countI) {
    jsonOut.i = i;
    print('page ${jsonOut.intOf('matches[i].page')}: ...${jsonOut.stringOf('matches[i].before')}[${jsonOut.stringOf('matches[i].text')}]${jsonOut.stringOf('matches[i].after')}...');
    i++;
  }

  // The search ignores case by default.  Set caseSensitive to find only the exact spelling.
  json.updateBool('caseSensitive', true);
  json.updateString('query', 'Chilkat');
  try {
    pdf.extractText('search', json, jsonOut);
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    return;
  }

  print('Case-sensitive matches for Chilkat: ${jsonOut.intOf('count')}');

  // Sample output:

  // Matches: 5
  // page 1: ...[Chilkat] River Field Notes The Chilkat...
  // page 1: ...Chilkat River Field Notes The [Chilkat] River runs for about fifty mi...
  // page 2: ...DAY ONE: UPPER [CHILKAT] FLATS Clear and cold, minus e...
  // page 2: ...he river is sometimes spelled [chilkat] in older records, and the val...
  // page 3: ...y because the fish run on the [Chilkat] was thinning. Two tagged bird...
  // Case-sensitive matches for Chilkat: 3
}