How can I use it for split and merge PDF's pages?

[Aminadav]

No description provided.

[insinfo]

here is a possible way
you can create extensions for missing methods in PDFiumBindings class
if you want you can also contribute with a PR

https://github.com/klippa-app/pdfium-cli/blob/main/cmd/merge.go
https://github.com/chromium/pdfium/blob/4ae353f1e22efea86262f9cdd4f0e8478f142182/public/fpdf_ppo.h#L49
https://pdfium.patagames.com/

import 'package:pdfium_bindings/pdfium_bindings.dart';
import 'package:ffi/ffi.dart';
import 'dart:ffi';



typedef _c_FPDF_LoadDocument = Pointer<fpdf_document_t__> Function(
  Pointer<Int8> file_path,
  Pointer<Int8> password,
);

typedef _dart_FPDF_LoadDocument = Pointer<fpdf_document_t__> Function(
  Pointer<Int8> file_path,
  Pointer<Int8> password,
);

// Basic data types
typedef FPDF_BYTESTRING = Pointer<Int8>;
typedef FPDF_BOOL = Int32;

/// function signature in the C API of the PDFium FPDF_ImportPages function
typedef _c_FPDF_ImportPages = FPDF_BOOL Function(
  Pointer<fpdf_document_t__> dest_doc,
  Pointer<fpdf_document_t__> src_doc,
  FPDF_BYTESTRING pagerange,
  Int32 index,
);

/// equivalent signature in dart of PDFium FPDF_ImportPages function
typedef _dart_FPDF_ImportPages = int Function(
  Pointer<fpdf_document_t__> dest_doc,
  Pointer<fpdf_document_t__> src_doc,
  FPDF_BYTESTRING pagerange,
  int index,
);

/// example extension that adds the FPDF_ImportPages function
extension PDFiumBindingsExtensions on PDFiumBindings {
  Pointer<fpdf_document_t__> FPDF_LoadDocument2(Pointer<Int8> file_path,
      Pointer<Int8> password, DynamicLibrary dynamicLibrary) {
    final _lookup = dynamicLibrary.lookup;

    final _FPDF_LoadDocument_ptr =
        _lookup<NativeFunction<_c_FPDF_LoadDocument>>('FPDF_LoadDocument');

    final _dart_FPDF_LoadDocument _FPDF_LoadDocument =
        _FPDF_LoadDocument_ptr.asFunction<_dart_FPDF_LoadDocument>();

    return _FPDF_LoadDocument(
      file_path,
      password,
    );
  }

  /// Import pages to a FPDF_DOCUMENT.
  ///
  ///   dest_doc  - The destination document for the pages.
  ///   src_doc   - The document to be imported.
  ///   pagerange - A page range string, Such as "1,3,5-7". The first page is one.
  ///               If |pagerange| is NULL, all pages from |src_doc| are imported.
  ///   index     - The page index at which to insert the first imported page into
  ///               |dest_doc|. The first page is zero.
  ///
  /// Returns TRUE on success. Returns FALSE if any pages in |pagerange| is
  /// invalid or if |pagerange| cannot be read.
  /// https://github.com/chromium/pdfium/blob/4ae353f1e22efea86262f9cdd4f0e8478f142182/public/fpdf_ppo.h#L49
  int FPDF_ImportPages(Pointer<fpdf_document_t__> dest_doc, Pointer<fpdf_document_t__> src_doc,
      FPDF_BYTESTRING pagerange, int index, DynamicLibrary dynamicLibrary) {
    final _lookup = dynamicLibrary.lookup;

    final _FPDF_ImportPages_ptr =
        _lookup<NativeFunction<_c_FPDF_ImportPages>>('FPDF_ImportPages');

    final _dart_FPDF_ImportPages _FPDF_ImportPages =
        _FPDF_ImportPages_ptr.asFunction<_dart_FPDF_ImportPages>();

    return _FPDF_ImportPages(
      dest_doc,
      src_doc,
      pagerange,
      index,
    );
  }



}


import 'dart:ffi';
import 'dart:io';

import 'package:certificadox509/teste.dart';
import 'package:ffi/ffi.dart';
import 'package:image/image.dart';
import 'package:path/path.dart' as path;
import 'package:pdfium_bindings/pdfium_bindings.dart';

void main() {
  final libraryPath = path.join(Directory.current.path, 'pdfium.dll');
  final dll = DynamicLibrary.open(libraryPath);
  final pdfium = PDFiumBindings(dll);

  const allocate = calloc;

  final config = allocate<FPDF_LIBRARY_CONFIG>();
  config.ref.version = 2;
  config.ref.m_pUserFontPaths = nullptr;
  config.ref.m_pIsolate = nullptr;
  config.ref.m_v8EmbedderSlot = 0;
  pdfium.FPDF_InitLibraryWithConfig(config);

  final destFilePath = stringToNativeInt8('sample.pdf');
  final srcFilePath = stringToNativeInt8('1417.pdf');

  final destDoc = pdfium.FPDF_LoadDocument(destFilePath, nullptr);
  if (destDoc == nullptr) {
    final err = pdfium.FPDF_GetLastError();
    throw PdfiumException.fromErrorCode(err);
  }

  final destDocPageCount = pdfium.FPDF_GetPageCount(destDoc);
  print('destDocPageCount: $destDocPageCount');

  final srcDoc = pdfium.FPDF_LoadDocument(srcFilePath, nullptr);
  if (srcDoc == nullptr) {
    final err = pdfium.FPDF_GetLastError();
    throw PdfiumException.fromErrorCode(err);
  }

  final srcDocPageCount = pdfium.FPDF_GetPageCount(srcDoc);
  print('srcDocPageCount: $srcDocPageCount');

  final ret = pdfium.FPDF_ImportPages(
      destDoc, srcDoc, stringToNativeInt8('5000'), 0, dll);
  print('FPDF_ImportPages: $ret');


  // free

  allocate.free(destFilePath);
  allocate.free(srcFilePath);

  pdfium.FPDF_CloseDocument(srcDoc);
  pdfium.FPDF_CloseDocument(destDoc);

  pdfium.FPDF_DestroyLibrary();
  allocate.free(config);
}