Flusseract #

Flutter plugin for the Tesseract OCR C++ library. This plugin provides bindings to Flutter that are similar to that provided by the gosseract SDK for Golang.

Getting Started #

This project depends on the Tesseract OCR libraries which must be installed to your development or build environment before you can run the example provided or add and use it as a dependency in your application.

If you wish to build Tessaract from source additional detail for different build platforms can be found below in addition to the official documentation for building from source.

Mac OS Build #

Install Dependencies

# Packages which are always needed.
brew install \
  automake \
  autoconf \
  libtool \
  pkgconfig \
  icu4c \
  leptonica
# Packages required for training tools.
brew install pango
# Optional packages for extra features.
brew install libarchive
# Optional package for builds using g++.
brew install gcc

Compile

git clone https://github.com/tesseract-ocr/tesseract/ && cd tesseract
./autogen.sh && mkdir build && cd build
# Optionally add CXX=g++-8 to the configure command if you really want to use a different compiler.
BREW_PKG_PATH=/opt/homebrew/opt
../configure \
  PKG_CONFIG_PATH=${BREW_PKG_PATH}/icu4c/lib/pkgconfig:${BREW_PKG_PATH}/libarchive/lib/pkgconfig:${BREW_PKG_PATH}/libffi/lib/pkgconfig \
  && make -j
# Optionally install Tesseract.
make install
# Optionally build and install training tools.
make training
make training-install

Project structure #

This template uses the following structure:

• src: Contains the native source code, and a CmakeFile.txt file for building that source code into a dynamic library.

• lib: Contains the Dart code that defines the API of the plugin, and which calls into the native code using dart:ffi.

• platform folders (android, ios, windows, etc.): Contains the build files for building and bundling the native code library with the platform application.

Building and bundling native code #

The pubspec.yaml specifies FFI plugins as follows:

  plugin:
    platforms:
      some_platform:
        ffiPlugin: true

This configuration invokes the native build for the various target platforms and bundles the binaries in Flutter applications using these FFI plugins.

This can be combined with dartPluginClass, such as when FFI is used for the implementation of one platform in a federated plugin:

  plugin:
    implements: some_other_plugin
    platforms:
      some_platform:
        dartPluginClass: SomeClass
        ffiPlugin: true

A plugin can have both FFI and method channels:

  plugin:
    platforms:
      some_platform:
        pluginClass: SomeName
        ffiPlugin: true

The native build systems that are invoked by FFI (and method channel) plugins are:

• For Android: Gradle, which invokes the Android NDK for native builds.
  • See the documentation in android/build.gradle.
• For iOS and MacOS: Xcode, via CocoaPods.
  • See the documentation in ios/image_processor.podspec.
  • See the documentation in macos/image_processor.podspec.
• For Linux and Windows: CMake.
  • See the documentation in linux/CMakeLists.txt.
  • See the documentation in windows/CMakeLists.txt.

Flutter help #

For help getting started with Flutter, view our online documentation, which offers tutorials, samples, guidance on mobile development, and a full API reference.