# vision.stack -- computer vision, kept out of the desktop stack.
# stack-version: 1.14.320
#
# WHAT THIS MACHINE NEVER BUILDS is in avoid.stack, included by every stack
# here: the exclusions are a property of the machine, not of one stack.
# Without it a dependency plan walks into systemd, qt6, cups and texlive.
include avoid

#
# Replay with:  packagemanager stack vision --run
#
# WHY ITS OWN STACK.  OpenCV is hours of compiling, it is nobody's
# dependency here, and a desktop works perfectly without it -- so it has no
# business in sway.stack, where every entry is something the desktop needs.
# Anything else of this shape (a big optional toolkit, built because you use
# it rather than because something requires it) belongs here too.
#
# None of this is in the BLFS book.  That means the ref, the build line and
# the probe are ours to keep true, and the entry says what was checked.

# opencv 5.
#
# CHECKED: `git ls-remote` lists branch 5.x and tag 5.0.0 (and a
# 5.0.0-alpha).  The tag is pinned rather than the branch -- 5.x moves, and
# a build that worked is worth being able to repeat.  To follow development
# instead, ref=5.x, and then write down the commit that built.
#
# The build is the same one you would run by hand:
#
#     cmake -DOPENCV_GENERATE_PKGCONFIG=ON -DCMAKE_INSTALL_PREFIX=/usr ../opencv
#     make -j16 && make install
#
# ...with two differences, both deliberate:
#
#   * `cmake -S . -B build` instead of a sibling build directory.  The
#     clone lands in opencv-git and the phases resume inside it, so the
#     build directory has to be under it -- a `../opencv` layout would put
#     it outside the tree the package user owns.
#   * `cmake --build build` instead of `make -j16`.  It reads
#     CMAKE_BUILD_PARALLEL_LEVEL, which lfs-helper exports from `jobs` in
#     machine.conf or from --jobs, so the count lives in one place instead
#     of being typed into this line.
#
# OPENCV_GENERATE_PKGCONFIG=ON is kept: upstream stopped generating the .pc
# file by default at 4.x, and everything that links OpenCV outside cmake
# needs it.
#
# Expect it to want collector groups on the way: the python bindings go into
# python's site-packages and the .pc into pkgconfig's directory, both owned
# by other packages.  The repair asks which group to share and retries.
git    opencv \
       url=https://github.com/opencv/opencv.git \
       ref=5.0.0 \
       prog=opencv_version \
       have=/usr/bin/opencv_version \
       build="cmake -S . -B build -D OPENCV_GENERATE_PKGCONFIG=ON -D CMAKE_INSTALL_PREFIX=/usr -D CMAKE_BUILD_TYPE=Release -D CMAKE_SKIP_INSTALL_RPATH=ON; cmake --build build" \
       install="cmake --install build" \
       expect="opencv_version | grep -q '^5'"

# WHAT THE FIRST REAL BUILD SHOWED (5.0.0, this machine):
#
#   Unavailable: java python3          <- no numpy, so no cv2 for python
#   Eigen: NO                          <- Posegraph optimization stays off
#   OpenEXR: NO
#   Lapack: built-in libclapack        <- no system BLAS/LAPACK
#   FFMPEG: YES, GStreamer: YES, v4l2: YES, GTK3 highgui, OpenCL: YES
#
# The python bindings are the one most people miss: cmake reports
#     ModuleNotFoundError: No module named 'numpy'
# and then lists python3 as Unavailable -- a full build with no cv2 at the
# end of it.  If you want them, numpy first -- WITH --recursive, because
# numpy's own Required is `cython, meson_python` and a plain install builds
# one package:
#     packagemanager install numpy --run --recursive
# ...then rebuild opencv, because bindings are decided at configure time.
#
# It also DOWNLOADS during configure: ippicv (Intel IPP) and a unicode font,
# from raw.githubusercontent.com.  So this entry needs the network at build
# time, not just at fetch time, and a machine with no route to github cannot
# configure it at all.
#
# opencv_contrib is a SECOND repository whose modules are built by pointing
# opencv's OPENCV_EXTRA_MODULES_PATH at it, not by building it on its own.
# Nothing here needs it, so it is not an entry: if you want it, clone it
# beside opencv and add
#     -D OPENCV_EXTRA_MODULES_PATH=<path>/modules
# to the build line above.  Written down rather than added, because an entry
# that builds nothing on its own would be a lie about how that repo works.