build_opencv_macos.sh

#!/usr/bin/env bash

#
# This script assumes the user has admin rights. El Capitan (macOS 10.11) tightened up scurity:
#
# 1. Homebrew seems to have problems modifying with the /usr/local directory. This is addressed
# in this script by explicitly setting access rights (although this behaviour can be changed).
#
# 2. The webcam can't be accessed from the terminal using OpenCV in Python or C++ until you
# accept a system prompt to grant access. Simply running a C++ executable does not seem to
# generate a prompt; running a Python script that accesses the camera via OpenCV *does* generate
# a prompt, after which you can also run the C++ executable without issues.
#

# Choose your desired OpenCV version, and a name for the Python virtual environments directory
OpenCV_version="4.1.1"
VirtualEnvs_dir=".virtualenvs"

# To which profile script should we add any required path setup etc?
profile_file="${HOME}/.bash_profile"

# The directory from which this script was run
workdir=$(pwd)

# Some default directory names
OpenCV_dir="${workdir}/OpenCV-${OpenCV_version}"
OpenCV_source_dir="${OpenCV_dir}/opencv-${OpenCV_version}"
OpenCV_build_dir="${OpenCV_dir}/opencv-${OpenCV_version}/build"
OpenCV_contrib_dir="${OpenCV_dir}/opencv_contrib-${OpenCV_version}"


# ---------------------------------------------------------
# 0. main() runs the separate parts of the install process;
#    comment stages out if/as appropriate.
# ---------------------------------------------------------
function main
{
	install_homebrew || print_and_exit "Unable to install Homebrew"
	install_python   || print_and_exit "Unable to install Python3"
	install_ant      || print_and_exit "Unable to install Ant"
	install_misc     || print_and_exit "Unable to install misc. items"
	retrieve_source  || print_and_exit "Unable to retrieve OpenCV source code"
	build_source     || print_and_exit "Unable to build OpenCV source code"
	install_opencv   || print_and_exit "Unable to install OpenCV"
}


# ---------------------------------------------------------------
# 1. Install Homebrew ( https://brew.sh/ ) and ensure up-to-date:
# ---------------------------------------------------------------
function install_homebrew
{
	print_header "Installing homebrew ..."
	check_installed "brew" && return 0
	
	/usr/bin/ruby -e "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/master/install)"
	brew update

	# Homebrew website suggests this as a removal command ( https://docs.brew.sh/FAQ ):
	# ruby -e "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/master/uninstall)"
}


# --------------------------------
# 2. Install Python3 via Homebrew:
# --------------------------------
function install_python
{
	#
	# Homebrew on macOS El Capitan (10.11) and above has problems with /usr/local/
	# which breaks some post-install scripts for python; this manifests as e.g.
	# no "pip3" command (though "python3 -m pip ..." works).
	#
	# We therefore have multiple approaches:
	#
	# 1. Ensure certain required directories are created, and set access rights
	#    that allow Homebrew to manipulate them, before installing python
	#
	# 2. Install pip explicitly after python installed
	#
	# In any case, "brew install python" should result in the availability of
	# both python2 (>= 2.7.1) and python3 (>= 3.7.4). TensorFlow etc are now
	# compatible with python v3.7, so don't worry about needing v3.6 etc.
	#
	# Here, I'm using approach #1.
	#

	print_header "Installing python3 ..."
	check_installed "pip3" && return 0
	check_installed "brew" || print_and_exit "Homebrew not found"

	pip_install_option="1"

	if [[ "${pip_install_option}" == "1" ]]
	then

		sudo mkdir -p /usr/local/lib
		sudo mkdir -p /usr/local/Frameworks
		sudo chown -R $(whoami) $(brew --prefix)/*
		brew install python

	else
		brew install python
		curl -O https://bootstrap.pypa.io/get-pip.py
		sudo python3 get-pip.py
		sudo rm -rf get-pip.py ~/.cache/pip
	fi
}


# -------------------------------------------------------------------------------
# 3. Install ant, which should enable OpenCV build process to build Java wrappers
# -------------------------------------------------------------------------------
function install_ant
{
	print_header "Installing Ant ..."
	check_installed "ant" && return 0
	check_installed "brew" || print_and_exit "Homebrew not found"

	brew install ant
}


# ------------------------------------------------------------
# 3. Install misc prerequisites for building and using OpenCV:
# ------------------------------------------------------------
function install_misc
{
	print_header "Installing misc. items ..."
	check_installed "brew" || print_and_exit "Homebrew not found"
	check_installed "pip3" || print_and_exit "pip3 not found"

	brew install cmake
	brew install jpeg libpng libtiff openexr
	brew install eigen tbb

	sudo pip3 install virtualenvwrapper

	# Add some lines to profile file so we can use virtual Python environments:

	echo ""                                                       >> ${profile_file}
	echo "########### Added by OpenCV build script! ###########"  >> ${profile_file}
	echo "export WORKON_HOME=$HOME/${VirtualEnvs_dir}"            >> ${profile_file}
	echo "export VIRTUALENVWRAPPER_PYTHON=/usr/local/bin/python3" >> ${profile_file}
	echo "source /usr/local/bin/virtualenvwrapper.sh"             >> ${profile_file}
	echo "#####################################################"  >> ${profile_file}
	echo ""                                                       >> ${profile_file}

	# Ensure new environment settings are active in the current shell:

	[[ -f "${profile_file}" ]] || print_and_exit "${profile_file} not found"
	source ${profile_file}

	# Create a virtual python environment called "cv", ensure numpy is intalled in it.

	mkvirtualenv cv -p python3

	#
	# Ensure numpy is available in the "cv" virtual Python environment; virtual environments
	# don't inherit from the system environment by default. Note that recent macOS versions
	# ship with numpy in the python2 environment, so try not to get confused ...
	#

	workon cv
	sudo pip3 install numpy
}


# --------------------------------------------
# 4. Download/unpack OpenCV and contributions:
# --------------------------------------------
function retrieve_source
{
	print_header "Retrieving OpenCV (and contributions) source code ..."

	check_installed "virtualenvwrapper.sh" || print_and_exit "'workon' command not found"
	[[ -f "${profile_file}" ]] || print_and_exit "'${profile_file}' file not found"

	source ${profile_file}
	workon cv

	mkdir -p "${OpenCV_dir}"

	cd ${OpenCV_dir}

	curl -L -o "opencv-${OpenCV_version}.zip"         https://github.com/opencv/opencv/archive/${OpenCV_version}.zip
	curl -L -o "opencv_contrib-${OpenCV_version}.zip" https://github.com/opencv/opencv_contrib/archive/${OpenCV_version}.zip

	unzip "opencv-${OpenCV_version}.zip"
	unzip "opencv_contrib-${OpenCV_version}.zip"

	cd ${workdir}
}


# ----------------------------------
# 5. Build OpenCV and contributions:
# ----------------------------------
function build_source
{
	print_header "Building OpenCV (and contributions) ..."

	check_installed "cmake" || print_and_exit "'cmake' command not found"
	check_installed "virtualenvwrapper.sh" || print_and_exit "'workon' command not found"
	[[ -f "${profile_file}" ]] || print_and_exit "'${profile_file}' file not found"
	[[ -d "${OpenCV_source_dir}" ]] || print_and_exit "OpenCV source directory ('${OpenCV_source_dir}') not found"
	[[ -d "${OpenCV_contrib_dir}" ]] || print_and_exit "OpenCV contrib source directory ('${OpenCV_contrib_dir}') not found"

	source ${profile_file}
	workon cv

	mkdir ${OpenCV_build_dir}
	cd ${OpenCV_build_dir}

	#
	# Get version'd python library file path.
	#

	cfg=$(python-config --configdir)
	maj=$(python --version | awk '{split($2,t,"."); print t[1]}')
	min=$(python --version | awk '{split($2,t,"."); print t[2]}')
	py_lib="${cfg}/libpython${maj}.${min}.dylib"

	#
	# Get Python include directory: Skip leading "-I" of first token in results from
	# "python-config --includes", and add a trailing slash.
	#

	tmp=$(python-config --includes | awk '{print $1}')
	py_inc="${tmp:2}/"

	#
	# Prepare makefiles etc; assumes e.g. "workon" used to set Python evironment,
	# and so "which python3" should return correct information. We override the
	# default Python executable to use Python3.
	#

	cmake \
	    -D CMAKE_BUILD_TYPE=RELEASE \
	    -D CMAKE_INSTALL_PREFIX=/usr/local \
	    -D OPENCV_EXTRA_MODULES_PATH="${OpenCV_contrib_dir}/modules" \
	    -D OPENCV_ENABLE_NONFREE=ON \
	    -D PYTHON3_LIBRARY=${py_lib} \
	    -D PYTHON3_INCLUDE_DIR=${py_inc} \
	    -D PYTHON3_EXECUTABLE=$(which python3) \
	    -D PYTHON_DEFAULT_EXECUTABLE=$(which python3) \
	    -D BUILD_opencv_python2=OFF \
	    -D BUILD_opencv_python3=ON \
	    -D BUILD_PERF_TESTS=OFF \
	    -D BUILD_TESTS=OFF \
	    ..

	#
	# Parallel make - as many processors as you feel brave enough to use!
	#

	make -j 8

	cd ${workdir}
}


# ------------------------------------
# 6. Install OpenCV and contributions:
# ------------------------------------
function install_opencv
{
	print_header "Installing OpenCV (and contributions) ..."

	check_installed "virtualenvwrapper.sh" || print_and_exit "'workon' command not found"
	[[ -f "${profile_file}" ]] || print_and_exit "'${profile_file}' file not found"
	[[ -d "${OpenCV_build_dir}" ]] || print_and_exit "Build directory ('${OpenCV_build_dir}') not found"

	source ${profile_file}
	workon cv

	cd ${OpenCV_build_dir}

	sudo make install

	cd ${workdir}

	# Ensure we can find our OpenCV on the Python path! Otherwise, we may have import problems.

	echo "export PYTHONPATH=\${PYTHONPATH}:${OpenCV_build_dir}/python_loader" >> ${profile_file}

	# Add symlink, so "import cv2" works in python:

	py_maj=$(python --version | awk '{split($2,t,"."); print t[1]}')
	py_min=$(python --version | awk '{split($2,t,"."); print t[2]}')

	src="/usr/local/lib/python${py_maj}.${py_min}/site-packages/cv2/python-{py_maj}.${py_min}/cv2.cpython-${py_maj}${py_min}m-darwin.so"
	dst="${HOME}/${VirtualEnvs_dir}/cv/lib/python${py_maj}.${py_min}/site-packages/cv2.so"

	echo "Adding symbolic link: ln -s ${src} ${dst}"

	ln -s ${src} ${dst}
}

# ------------------------
# Misc. utility functions:
# ------------------------
function print_header
{
	echo "" ; echo "#" ; echo "# ${1} ..." ; echo "#" ; echo ""
}

function print_and_exit
{
	echo "!" ; echo "! Exiting because: ${1}" ; echo "!"
	exit
}

function check_installed
{
	result=$(which ${1})
	[[ ${result} == "" ]] && return 1
	echo "Command '${1}' appears to be present (${result})."
}


# -------------------------------------------------
# Run main(), now the whole script has been parsed!
# -------------------------------------------------

main "$@" ; exit