Developer note: Windows ARM64

Summary (private note for this library author): - Cpp: use ARM64 build

cmake .. -DOpenCV_DIR=F:/dvp/_opencv/opencv4.6.0_arm64_dll_world -DCMAKE_GENERATOR_PLATFORM=ARM64 -DHELLOIMGUI_USE_SDL_OPENGL3=ON

  • Python: prefer python x64 aka amd64 (because numpy does not work on python arm64)

F:\Utils\Python311-amd64\python.exe -m venv venv_x64
.\venv_x64\Scripts\activate
pip install -v .
pip install opencv-contrib-python
demo_imgui_bundle

There is no prebuild version of OpenCV for Windows ARM64. See instructions below, in order to build your own.

Note: if you are on windows ARM64 and want to build for x64 use: cmake .. -A x64

Using a "world" dll version of OpenCV

Build and install a DLL "world" version of OpenCV for ARM64

(world means you get only one dll for all OpenCV)

The two important options are INSTALL_CREATE_DISTRIB (will create dll opencv_world), BUILD_SHARED_LIBS=ON (required for world build).

You can tweak the other options, which are here to reduce the build time.

(**Change the last parameter of the cmake command to your desired installation path**)
mkdir build_arm64_dll_world
cd build_arm64_dll_world

cmake ../opencv_git -DINSTALL_CREATE_DISTRIB=ON -DBUILD_SHARED_LIBS=ON -A ARM64 -DCMAKE_BUILD_TYPE=Release -DBUILD_opencv_apps=OFF -DBUILD_TESTS=OFF -DBUILD_PERF_TESTS=OFF -DBUILD_opencv_python2=OFF -DBUILD_opencv_python3=OFF -DCMAKE_INSTALL_PREFIX=F:/dvp/_OpenCV/opencv4.6.0_arm64_dll_world

cmake --build . --config Release
cmake --install . --config Release

cmake --build . --config Debug
cmake --install . --config Debug

cd ..

Build ImGui Bundle pip package on Windows ARM64 with "world" opencv

Note / December 2022: at the time of writing, the pip package "opencv-python" refuses to build with python ARM64 on windows. imgui_bundle does work however but one cannot use opencv (aka cv2) from python.

You need an arm version of python. See https://www.python.org/downloads/windows/ (if you need pip, youd need the full setup, not the embeddable version)

Set OpenCV env variables:

  • OpenCV_DIR=/path/to/your/opencv_world_install

  • CMAKE_GENERATOR_PLATFORM=ARM64

Not so funny note: there are at least 4 incompatible ways to set an env var in Windows.

  • The clicky way

  • with PowerShell Set-Item -Path 'Env:OpenCV_DIR' -Value 'F:/dvp/_opencv/opencv4.6.0_arm64_dll_world' Set-Item -Path 'Env:CMAKE_GENERATOR_PLATFORM' -Value 'ARM64'

  • With bash export OpenCV_DIR=F:/dvp/_opencv/opencv4.6.0_arm64_dll_world export CMAKE_GENERATOR_PLATFORM=ARM64

  • With dos set OpenCV_DIR=F:/dvp/_opencv/opencv4.6.0_arm64_dll_world set CMAKE_GENERATOR_PLATFORM=ARM64

Then, pip install:

pip install -v .

Build CppLib on Windows ARM64 with world OpenCV

Specify cmake options

cmake .. -DOpenCV_DIR=F:/dvp/_opencv/opencv4.6.0_arm64_dll_world -DCMAKE_GENERATOR_PLATFORM=ARM64

Explanations:

  • OpenCV_DIR: you opencv install path

  • CMAKE_GENERATOR_PLATFORM: tells openCV to look in the ARM64 folder

Using a static version of OpenCV

Build and install a static version of OpenCV for ARM64

Git clone and checkout v4.6.0

mkdir _opencv
cd _opencv
git clone https://github.com/opencv/opencv.git opencv_git
cd opencv_git
git checkout 4.6.0
cd ..

Build and install OpenCV with those settings (Change the last parameter of the cmake command to your desired installation path)

The important option is BUILD_SHARED_LIBS=OFF. You can tweak the other options, which are here to reduce the build time.

mkdir build_ARM64
cd build_ARM64

cmake ../opencv_git -A ARM64 -DCMAKE_BUILD_TYPE=Release -DBUILD_SHARED_LIBS=OFF -DBUILD_opencv_apps=OFF -DBUILD_TESTS=OFF -DBUILD_PERF_TESTS=OFF -DBUILD_opencv_python2=OFF -DBUILD_opencv_python3=OFF -DBUILD_JASPER=OFF -DWITH_JASPER=OFF -DWITH_CUDA=OFF -DWITH_FFMPEG=OFF -DWITH_GTK=OFF -DCMAKE_INSTALL_PREFIX=F:/dvp/_OpenCV/opencv4.6.0_static_install_win_vc17

cmake --build . --config Release
cmake --install .
cd ..

Build ImGui Bundle pip package on Windows ARM64 with static OpenCV

You need an arm version of python. See https://www.python.org/downloads/windows/ (if you need pip, youd need the full setup, not the embeddable version)

Set OpenCV env variables: * with PowerShell

Set-Item -Path 'Env:OpenCV_DIR' -Value 'F:/dvp/_opencv/opencv4.6.0_static_install_win_vc17'
Set-Item -Path 'Env:OpenCV_STATIC' -Value 'ON'
Set-Item -Path 'Env:CMAKE_GENERATOR_PLATFORM' -Value 'ARM64'

  • With bash:

    export OpenCV_DIR=F:/dvp/_opencv/opencv-4.6.0-vc14_vc15/opencv/build

  • With dos:

    set OpenCV_DIR=F:/dvp/_opencv/opencv-4.6.0-vc14_vc15/opencv/build

Build CppLib on Windows ARM64 with static OpenCV

Specify cmake options

cmake .. -DOpenCV_DIR=F:/dvp/_opencv/opencv4.6.0_static_install_win_vc17 -DOpenCV_STATIC=ON -DCMAKE_GENERATOR_PLATFORM=ARM64 -DBUILD_SHARED_LIBS=OFF -DCMAKE_MSVC_RUNTIME_LIBRARY=MultiThreaded

Explanations:

  • OpenCV_DIR: you opencv install path

  • CMAKE_GENERATOR_PLATFORM: tells openCV to look in the ARM64 folder

  • OpenCV_STATIC: tells OpenCV to look in the ARM64/vc17/staticlib folder

  • CMAKE_MSVC_RUNTIME_LIBRARY: tells MSVC to use static runtime (/MT)

  • BUILD_SHARED_LIBS=OFF: build static libs. Normally, this could be ignored

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