opencv_dart 0.6.4

OpenCV4 bindings for Dart language and Flutter, using dart:ffi. The most complete OpenCV bindings for Dart!

opencv_dart

OpenCV Bindings for Dart Language.

!!!This package is experimental and APIs may change in the future!!!

WIP, contributions are welcome!

Platform	Supported	Tested	Prebuilt Binaries
Android	✅	☑️	x86_64, arm64-v8a, armeabi-v7a
iOS	❌	❌	❌
Linux	✅	✅	x64
Windows	✅	✅	x64
macOS	✅	✅	x64, arm64

• I have no Apple devices, so iOS and macOS are not supported yet macOS compiled by Github Workflow available now, try it!
• Theorically the dart codes will work for iOS, you can compile binaries by yourself, contributions are welcome!

IMPORTANT

After added to pubspec.yaml or install by commandline, please run dart run opencv_dart:setup <platform> --arch <arch> to download prebuilt binaries.

• platform: auto android linux windows macos
• arch: auto x86 x64 arm64(macOS only) x86_64(android only) arm64-v8a(android only) armeabi-v7a(android only)
• run dart run opencv_dart:setup -h to see more options

Please use v0.3.0 and later version.

Example

[example]

Status

module	Binding status	Test status	description
aruco	✅	✅	ArUco module
core	✅	✅	Core module
features2d	✅	✅	Features2D module
highgui	✅	✅	HighGUI module
imgcodecs	✅	✅	ImageCodecs module
imgproc	✅	✅	ImageProc module
objdetect	✅	✅	Object Detection module
svd	✅	✅	SVD module
video	✅	✅	Video module
videoio	✅	✅	VideoIO module
asyncarray	✅	✅	AsyncArray module
calib3d	✅	✅	Calib3D module
dnn	✅	✅	DNN module
photo	✅	✅	Photo module
stitching	☑️	☑️	Stitching module
cuda	❌	❌	CUDA module
contrib	❌	❌	Contrib module

• ❌ : not finished
• ☑️ : partially supported
• ✅ : finished
• videoio: cv.VideoCapture from file is not supported yet supported now.

Usage

import 'package:opencv_dart/opencv_dart.dart' as cv;

void main() {
  final img = cv.imread("test/images/lenna.png", flags: cv.IMREAD_COLOR);
  final gray = cv.Mat.empty();

  cv.cvtColor(img, gray, cv.COLOR_BGR2GRAY);
  print("${img.rows}, ${img.cols}");

  cv.imwrite("test_cvtcolor.png", gray);
}

More examples are on the way...

TODO

• ✅ compile libs for android, linux
• ❌ support for iOS, macOS
• ❌ add more examples
• ❌ documentation
• ❌ modify C wrapper to catch exceptions
• ❌ Native Assets
• ❌ async?
• ✅ directly include opencv source code, refactor cmakelists.txt

For Developers

This package is in heavy development, dynamic libraries for Windows and linux have been compiled, for other platforms, you need to compile it yourself.

How to compile

1. prepare a compiler.

   windows: Install Visual Studio 2019 or Later

   ubuntu: reference opencv official build guide to install

   sudo apt-get install build-essential libgtk-3-dev ffmpeg libavcodec-dev cmake \
      ninja-build ccache nasm libavformat-dev libavutil-dev libswscale-dev \
      libgflags-dev python3 libjpeg-dev libpng-dev libtiff-dev python3-pip
   

   macos:

   brew install --force --overwrite ninja ccache ffmpeg nasm cmake
   

   from v0.6.4, build system has been migrated to conan

      python3 -m pip install conan
      conan profile detect -f
   

2. clone this repo, git clone https://github.com/rainyl/opencv_dart.git

3. cd opencv_dart

4. compile

   for windows:

   conan build . -b missing -s compiler.cppstd=20
   

   for linux, macos:

   conan build . -b missing
   

   for android, you need to download android ndk and opencv for android sdk, extract opencv sdk and copy and rename OpenCV-android-sdk to build/opencv/android directory. NO need for opencv sdk now, will be compiled from source to enable contrib modules

   conan build . -b missing -pr:h profiles/android-<arch> -c tools.android:ndk_path="<ABSOLUTE path for ndk>"
   

5. If you want to test using vscode, add dynamic library path to "dart.env" in settings.json

Acknowledgement

• gocv project: https://github.com/hybridgroup/gocv License: Apache-2.0

License

Apache-2.0 License