Chilkat for Dart and Flutter — the chilkat package

Add to your project

dart pub add chilkat      # or: flutter pub add chilkat

or add the dependency to pubspec.yaml by hand:

dependencies:
  chilkat: ^11.6.1

Then build or run as usual (dart run, flutter run, flutter build). On the first build the package's build hook downloads chilkat-dart-<os>-<arch>.tar.gz for your target from https://chilkatdownload.com/<version>/, checks its SHA-256 against the table compiled into the package, unpacks it into the build cache, and bundles the shared library with your application (libchilkat_c_bridge.so, libchilkat_c_bridge.dylib or chilkat_c_bridge.dll). Later builds reuse the cached, verified copy, so the download happens once per Chilkat version per target. A Flutter app that targets several platforms gets the library for each one automatically.

Quick start

import 'package:chilkat/chilkat.dart';

void main() {
  // Any string unlocks the fully functional 30-day trial. Call once per isolate.
  Chilkat.unlockBundle('Anything for 30-day trial');

  final http = CkHttp();
  http.connectTimeout = 30;
  http.setRequestHeader('Accept', 'application/json');

  try {
    final body = http.quickGetStr('https://api.github.com/repos/dart-lang/sdk');
    final json = CkJsonObject();
    json.load(body);
    print('${json.intOf('stargazers_count')} stars');
  } on ChilkatException catch (e) {
    print(e);                // CkHttp.quickGetStr failed: <reason>
    print(e.lastErrorText);  // the full Chilkat log of the failed call
  }
}

A method that can fail throws ChilkatException instead of returning a status. The exception carries the object's LastErrorText from the moment of the failure (e.lastErrorText), the class and method names, and a one-line message. Objects release their native resources when garbage collected; call dispose() to release them immediately (a large CkBinData, an open socket).

Supported targets

A prebuilt Chilkat shared library is published for each of these targets with every Chilkat release. The archive is what the build hook downloads; the name is chilkat-dart-<os>-<arch>[-simulator].tar.gz.

The build hook chooses the archive from the target of the build (the platform and architecture Flutter or dart build is producing), not from the host, so cross-building for Android or iOS from a desktop works the same way. A target not in this table fails the build with a message naming the supported targets; if you need another one, contact Chilkat support.

Flutter and long-running calls

Every Chilkat call is synchronous and blocks the calling isolate. Quick operations (JSON, XML, hashing, encoding) are fine on the UI isolate; network and large file operations belong in a worker isolate so the UI stays responsive. Chilkat objects cannot be sent between isolates, so the worker creates its own:

final body = await Isolate.run(() {
  final http = CkHttp()..connectTimeout = 30;
  return http.quickGetStr(url);
});

Progress and cancellation: the event-capable classes (CkHttp, CkFtp2, CkSFtp, CkZip, CkImap, …) have onPercentDone, onProgressInfo and onAbortCheck callback properties. They fire on the calling thread, inside the method call; return true from onPercentDone or onAbortCheck to abort. From a worker isolate, forward progress to the UI through a SendPort:

final progress = ReceivePort();
progress.listen((pct) => setState(() => _pct = pct as int));
await Isolate.run(() {
  final ftp = CkFtp2()..hostname = host ..username = user ..password = pw;
  ftp.onPercentDone = (pct) { progress.sendPort.send(pct); return false; };
  ftp.connect();
  ftp.getFile('remote.dat', localPath);
});

The *Async methods, Task and TaskChain of other Chilkat products are not part of the Dart package; isolates are the Dart way to run work in the background.

Offline builds, vendoring, and your own Chilkat library

Build machines without internet access, or that must not download during a build, point the build hook at a library directory instead. Build hooks do not see the caller's environment variables, so the setting is a user-define in the application's pubspec.yaml (the root package of the build, not a library package it depends on):

hooks:
  user_defines:
    chilkat:
      lib_dir: /opt/chilkat/lib      # the directory containing libchilkat_c_bridge.so,
                                     # libchilkat_c_bridge.dylib or chilkat_c_bridge.dll;
                                     # a relative path resolves against this pubspec.yaml

With lib_dir set, nothing is downloaded. To populate that directory, download the archive for your target once from a connected machine and unpack it — the URL is

https://chilkatdownload.com/<version>/chilkat-dart-<os>-<arch>.tar.gz

# for example, for chilkat 11.6.1 on 64-bit Linux:
https://chilkatdownload.com/11.6.1/chilkat-dart-linux-x64.tar.gz

where <version> is the exact version of the chilkat package you depend on (shown on pub.dev and in pubspec.lock). Each archive contains the shared library, license.pdf, a software bill of materials, and a VERSION file. The SHA-256 of every published archive is listed in lib/src/checksums.dart inside the package of the same version.

All build-hook settings (user-defines under hooks: user_defines: chilkat:):

A checksum mismatch fails the build rather than bundling an unverified library. (The environment variables CHILKAT_DART_LIB_DIR, CHILKAT_DART_CACHE_DIR and CHILKAT_DOWNLOAD_BASE are honoured too, but only by a hook runner that passes the environment through, which the standard Dart and Flutter tooling does not.)

How the Chilkat API maps to Dart

The reference documentation shows the exact Dart signature of every member, and the same text is available as dartdoc in your IDE.

Licensing

This is the full-version Chilkat product. Chilkat libraries are fully functional for a 30-day evaluation; passing any non-empty string to Chilkat.unlockBundle starts the trial, and a purchased unlock code removes the time limit. The license terms are in the LICENSE file of the package (and license.pdf in every native archive). For questions, see the reference documentation or contact Chilkat support.