find_text.dart

///Package imports
import 'package:flutter/material.dart';
import 'package:flutter/services.dart';

///Pdf import
import 'package:syncfusion_flutter_pdf/pdf.dart';

///Local imports
import '../../model/sample_view.dart';
import 'helper/save_file_mobile.dart'
    if (dart.library.js_interop) 'helper/save_file_web.dart';

/// Find text from the PDF document
class FindTextPdf extends SampleView {
  /// Find text from the PDF document.
  const FindTextPdf(Key key) : super(key: key);
  @override
  _FindTextPdfState createState() => _FindTextPdfState();
}

class _FindTextPdfState extends SampleViewState {
  _FindTextPdfState();
  final TextEditingController _nameController = TextEditingController(
    text: 'PDF',
  );
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      backgroundColor: model.sampleOutputCardColor,
      body: SingleChildScrollView(
        child: Padding(
          padding: const EdgeInsets.fromLTRB(10, 10, 10, 10),
          child: Column(
            crossAxisAlignment: CrossAxisAlignment.start,
            children: <Widget>[
              Text(
                'This sample shows how to find a text along with bounds and page index in an existing PDF document.',
                style: TextStyle(fontSize: 16, color: model.textColor),
              ),
              const SizedBox(height: 20, width: 30),
              Center(
                child: SizedBox(
                  height: 60,
                  width: 300,
                  child: TextFormField(
                    decoration: InputDecoration(
                      labelText: 'Enter the text to find',
                      labelStyle: TextStyle(
                        color:
                            model.themeData.colorScheme.brightness ==
                                    Brightness.light
                                ? Colors.grey
                                : Colors.lightBlue,
                      ),
                    ),
                    controller: _nameController,
                    style: TextStyle(color: model.textColor),
                  ),
                ),
              ),
              const SizedBox(height: 20, width: 30),
              Row(
                mainAxisAlignment: MainAxisAlignment.center,
                children: <Widget>[
                  TextButton(
                    style: ButtonStyle(
                      backgroundColor: WidgetStateProperty.all<Color>(
                        model.primaryColor,
                      ),
                      padding:
                          model.isMobile
                              ? null
                              : WidgetStateProperty.all(
                                const EdgeInsets.symmetric(
                                  vertical: 15,
                                  horizontal: 15,
                                ),
                              ),
                    ),
                    onPressed: _viewTemplate,
                    child: const Text(
                      'View Template',
                      style: TextStyle(color: Colors.white),
                    ),
                  ),
                  const SizedBox(height: 10, width: 20),
                  TextButton(
                    style: ButtonStyle(
                      backgroundColor: WidgetStateProperty.all<Color>(
                        model.primaryColor,
                      ),
                      padding:
                          model.isMobile
                              ? null
                              : WidgetStateProperty.all(
                                const EdgeInsets.symmetric(
                                  vertical: 15,
                                  horizontal: 15,
                                ),
                              ),
                    ),
                    onPressed: _generatePDF,
                    child: const Text(
                      'Find and Highlight',
                      style: TextStyle(color: Colors.white),
                    ),
                  ),
                ],
              ),
            ],
          ),
        ),
      ),
    );
  }

  Future<void> _viewTemplate() async {
    final List<int> documentBytes = await _readDocumentData(
      'pdf_succinctly_template.pdf',
    );
    await FileSaveHelper.saveAndLaunchFile(documentBytes, 'pdf_succinctly.pdf');
  }

  Future<void> _generatePDF() async {
    //Load the PDF document.
    final PdfDocument document = PdfDocument(
      inputBytes: await _readDocumentData('pdf_succinctly_template.pdf'),
    );

    //Create PDF text extractor to find text.
    final PdfTextExtractor extractor = PdfTextExtractor(document);

    //Find the text
    final List<MatchedItem> result = extractor.findText(<String>[
      _nameController.text,
    ]);

    if (result.isEmpty) {
      document.dispose();
      _showDialog(_nameController.text);
    } else {
      //Highlight the searched text from the document.
      for (int i = 0; i < result.length; i++) {
        final MatchedItem item = result[i];

        //Get page.
        final PdfPage page = document.pages[item.pageIndex];

        //Set transparency to the page graphics.
        page.graphics.save();
        page.graphics.setTransparency(0.5);

        //Draw rectangle to highlight the text.
        page.graphics.drawRectangle(
          bounds: item.bounds,
          brush: PdfBrushes.yellow,
        );
        page.graphics.restore();
      }

      //Save and dispose the document.
      final List<int> bytes = await document.save();
      document.dispose();

      //Launch file.
      await FileSaveHelper.saveAndLaunchFile(bytes, 'find_text.pdf');
    }
  }

  Future<List<int>> _readDocumentData(String name) async {
    final ByteData data = await rootBundle.load('assets/pdf/$name');
    return data.buffer.asUint8List(data.offsetInBytes, data.lengthInBytes);
  }

  void _showDialog(String text) {
    showDialog<Widget>(
      context: context,
      builder: (BuildContext context) {
        return AlertDialog(
          title: const Text(''),
          content: Wrap(
            children: <Widget>[
              const Text('The text '),
              Text(text, style: const TextStyle(fontWeight: FontWeight.bold)),
              const Text(' is not found.'),
            ],
          ),
          actions: <Widget>[
            TextButton(
              onPressed: () {
                Navigator.of(context).pop();
              },
              child: const Text('Close'),
            ),
          ],
        );
      },
    );
  }
}