Dart Requires Chilkat v11.7.0+

Extract Text from a Two-Column PDF

See more PDF Text Extraction Examples

Demonstrates how multi-column pages are read. By default the columns are detected and each column is read top to bottom before the next ("columns": "auto"); "columns": "none" reads the full page width line by line, which interleaves the columns. The quality report tells how many columns were found. 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 two-column PDF used in this example is available at two_column_article.pdf

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

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

  // With the default options the columns are detected, and the text of the left column
  // comes before the text of the right column.
  try {
    pdf.extractText('text', json, jsonOut);
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    return;
  }

  print('Columns detected: ${jsonOut.intOf('quality.pages[0].columns')}');
  print('Reading order: ${jsonOut.stringOf('quality.pages[0].readingOrderSource')}');
  print(jsonOut.stringOf('text'));

  // "none" switches column detection off: the page is read across its full width, line by line,
  // so each output line holds a line of the left column followed by a line of the right column.
  // This is rarely wanted, but it shows what the detection does.
  json.updateString('columns', 'none');
  json.updateString('layout', 'lines');
  try {
    pdf.extractText('text', json, jsonOut);
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    return;
  }

  print('---- columns: none ----');
  print(jsonOut.stringOf('text'));

  // Sample output (abbreviated):

  // Columns detected: 2
  // Reading order: visual
  // The Harbor Lighthouse, Season Two
  // 
  // The harbor lighthouse was built in 1874 to mark the entrance to the inner channel. It operated continuously until 1968, ...
  // 
  // The restoration society took ownership in 2021 with three goals: ...
  // ...
  // The lantern room frame was stripped, primed and repainted in the original dark green. ...
  // ...
  // ---- columns: none ----
  // The Harbor Lighthouse, Season Two
  // The harbor lighthouse was built in 1874 to The lantern room frame was stripped, primed
  // mark the entrance to the inner channel. It and repainted in the original dark green. New
  // ...
}