Dart Requires Chilkat v11.7.0+

Why a PDF Text Replacement Is Refused: the Font Rule

See more PDF Text Replacement Examples

A PDF stores glyphs drawn with particular fonts, so new text can only be drawn when the original font can draw it. This example shows the two common refusals. A font embedded as a subset carries only the glyphs the document used: a value made of other characters is refused with the reason missingGlyph, and the report names the font and the characters it lacks. A font that is neither one of the standard 14 nor embedded (here Verdana) is refused with nonStandardUnembeddedFont, because Chilkat cannot know what a viewer will draw for it. A non-embedded Arial, Times New Roman or Courier New is treated as the standard font every viewer substitutes for it. Dart

import 'package:chilkat/chilkat.dart';

void main() {
  var success = false;

  // 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 quote_subset_font.pdf
  // and letter_verdana.pdf

  // 1. An embedded subset font: only the glyphs the document uses are in the PDF.
  final pdf = CkPdf();
  try {
    pdf.loadFile('qa_data/pdf/quote_subset_font.pdf');
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    return;
  }

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

  // The regular face's subset carries the characters of the quotation's text, among them the digits of
  // "58341".  A new number made of those digits can be drawn...
  json.updateString('labels[0].label', 'Quote #:');
  json.updateString('labels[0].value', '58314');
  try {
    pdf.textReplace('check', json, jsonOut);
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    return;
  }

  print('58314: ok = ${jsonOut.boolOf('ok')}');

  // ...but "Q" and "-" are not in the subset (nothing in the quotation's regular text uses them).
  json.updateString('labels[0].value', 'Q-58341');
  try {
    pdf.textReplace('check', json, jsonOut);
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    return;
  }

  print('Q-58341: ok = ${jsonOut.boolOf('ok')}');
  if (!jsonOut.boolOf('ok')) {
    // The problem names the font and the characters it cannot draw.
    print('    reason: ${jsonOut.stringOf('problems[0].reason')}');
    print('    font: ${jsonOut.stringOf('problems[0].font')}');
    print('    missing: ${jsonOut.stringOf('problems[0].chars')}');
  }

  // "apply" with a problem returns false and changes nothing.
  success = true;
  try {
    pdf.textReplace('apply', json, jsonOut);
  } on ChilkatException {
    success = false;
  }
  print('apply returned $success, applied = ${jsonOut.boolOf('applied')}');

  // 2. A font that is not embedded and not one of the standard 14.
  final pdf2 = CkPdf();
  try {
    pdf2.loadFile('qa_data/pdf/letter_verdana.pdf');
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    return;
  }

  final json2 = CkJsonObject();
  json2.updateString('labels[0].label', 'Account Number:');
  json2.updateString('labels[0].value', '0000099999');
  try {
    pdf2.textReplace('check', json2, jsonOut);
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    return;
  }

  print('Verdana, not embedded: ok = ${jsonOut.boolOf('ok')}, reason: ${jsonOut.stringOf('problems[0].reason')}, font: ${jsonOut.stringOf('problems[0].font')}');

  // Sample output:

  // 58314: ok = true
  // Q-58341: ok = false
  //     reason: missingGlyph
  //     font: AAAAAA+DejaVuSans
  //     missing: Q-
  // apply returned false, applied = false
  // Verdana, not embedded: ok = false, reason: nonStandardUnembeddedFont, font: Verdana
}