Add CI support for building Windows on ARM wheels

[MugundanMCW]

PR Description:

• The adoption of Windows on ARM (WoA) devices is steadily increasing, yet many Python wheels are still not available for this platform.
• GitHub Actions now offer native CI runners for Windows on ARM devices (windows-11-arm), enabling automated builds and testing.
• Currently, official OpenCV Python wheels are not provided for Windows ARM64 and thus users/developers were facing difficulties using popular OpenCV library natively.
• This PR introduces support for building OpenCV wheels on Windows ARM64, improving accessibility for developers and end users on this emerging platform.
• Closes: Can not build the project in W11 on ARM64 #1092, Provide prebuilt Windows ARM64 packages #806

Changes Proposed:

• Added CI workflow for building and testing OpenCV wheels on new Windows on ARM github runners
• Added platform markers to use stable available NumPy for Windows on ARM builds.
• Added Windows on ARM specific condition logic to use NEON as baseline and dispatch unit, since MSVC lacks support for NEON_FP16, NEON_BF16 and NEON_DOTPROD intrinsics.

[MugundanMCW]

Hi @asmorkalov
Just to note here that these changes become obsolete if this PR got merged.

[Avasam]

That PR got merged

[MugundanMCW]

@Avasam thanks, will drop this change from the PR

[Avasam]

Unless I'm missing something big, couldn't .github/workflows/build_wheels_windows_arm.yml be replaced (avoiding tons of duplication that one could forget to update across configs) by updating strategy.matrix and strategy.matrix.include ?

    runs-on: ${{ matrix.os }}
    strategy:
      fail-fast: false
      matrix:
        python-version: ['3.11']
        platform: [x86, x64, arm64]
        with_contrib: [0, 1]
        without_gui: [0, 1]
        build_sdist: [0]
        include:
          - os: 'windows-2025'
          - platform: 'arm64'
            os: 'windows-11-arm'

[Avasam]

Similar here

    runs-on: ${{ matrix.os }}
    defaults:
      run:
        shell: cmd
    strategy:
      fail-fast: false
      matrix:
        python-version: ['3.7', '3.8', '3.9', '3.10', '3.11', '3.12', '3.13']
        platform: [x86, x64, arm64]
        with_contrib: [0, 1]
        without_gui: [0, 1]
        build_sdist: [0]
        include:
          - os: 'windows-2025'
          - platform: 'arm64'
            os: 'windows-11-arm'
        exclude:
          # actions/setup-python does not provide prebuilt arm64 Python before 3.11
          - platform: arm64
            python-version: "3.7"
          - platform: arm64
            python-version: "3.8"
          - platform: arm64
            python-version: "3.9"
          - platform: arm64
            python-version: "3.10"

[MugundanMCW]

Hi @Avasam,

I've addressed all the review comments and made the requested changes. Please let me know if there's anything else needed from my side to help move this PR toward merging.

Thanks!

[MugundanMCW]

Hi @asmorkalov & @Avasam
Could you take a look on the PR? I have adapted the requested changes.
Thanks

[Avasam]

I'm not a maintainer here. Just a contributor like you who's trying to get the best out of OpenCV-Python. Hopefully you get this merged soon because I could also really use it.

[Psychlist1972]

Hi All

Is there anything else required for this PR to move forward? This is an important part of a healthy Arm64 ecosystem.

Pete
Microsoft

[asmorkalov]

We have CI pipeline for Windows on ARM (Github provided virtual machine) in main OpenCV repo here: opencv/ci-gha-workflow#273. It's not merge yet, because it shows several accuracy test issues. The python packages are tested with smoke tests and python bindings specific tests only. We cannot release the package till the accuracy issue have been fixed.

[asmorkalov]

We have CI pipeline for Windows on ARM (Github provided virtual machine) in main OpenCV repo here: opencv/ci-gha-workflow#273. It's not merge yet, because it shows several accuracy test issues. The python packages are tested with smoke tests and python bindings specific tests only. We cannot release the package till the accuracy issue have been fixed.

[Psychlist1972]

We have CI pipeline for Windows on ARM (Github provided virtual machine) in main OpenCV repo here: opencv/ci-gha-workflow#273. It's not merge yet, because it shows several accuracy test issues. The python packages are tested with smoke tests and python bindings specific tests only. We cannot release the package till the accuracy issue have been fixed.

Thanks for the info!

Pete
Microsoft