Simple script to edit the OpenCV conda-forge feedstock's build script to enable CUDA support.

opencv-cuda.py

#!/opt/python/bin/python
# Installs a GPU-enabled OpenCV from the conda-forge feedstock.
# Assumes you already have Python 3 installed and the conda-forge channel on.

import argparse
import os.path
import subprocess
import sys

# These are the options we want to make sure are set to the values listed here.
#  - If they already exist in the build.sh script but are not set to the value
#    listed below, they are changed to that value.
#  - If they do not exist, they are appended with the given value.
OPTIONS = (
    ('DBUILD_TIFF', 1),
    ('DBUILD_PNG', 1),
    ('DBUILD_JPEG', 1),
    ('DWITH_CUDA', 1),
    ('DWITH_CUBLAS', 1),
    ('DCUDA_GENERATION', "Auto"),
    ('DINSTALL_C_EXAMPLES', 1),
    ('DWITH_FFMPEG', 1),
)

def pad_kv(option, value, arg_length):
    """
    Helper function which builds an argument line with the specified key-value
    pairing, inserting correct padding where needed.
    """
    padding = arg_length - 5 - 2
    kv = "{}={}".format(option, value)
    rhs = ("{:<" + str(padding) + "}\\\n").format(kv)  # This is the -2
    lhs = "    -"  # This is the -5
    line = "{}{}".format(lhs, rhs)
    if len(line) != arg_length:
        print("ERROR: Line length {} is not the specified arg length {}".format(len(line), arg_length), file = sys.stderr)
    return line

def insert(contents, to_insert, start_idx, end_idx):
    """
    Helper function which splits the original content, inserts the new
    content, and glues everything back together.
    """
    before = contents[:start_idx]
    after = contents[end_idx:]
    retval = "{}{}{}".format(before, to_insert, after)
    return retval

if __name__ == "__main__":
    # Pull in all the build.sh recipe contents.
    with open("build.sh", "r") as f:
        contents = f.read()

    # First, and arguably most importantly, find the newline corresponding to
    # the *last* compile option given. This is where new options will be 
    # inserted if they don't exist.
    last_option = contents.rfind("-D")
    insertion_index = contents.find("\n", last_option)
    idx = last_option
    while contents[idx] != "\n": idx -= 1
    arg_length = insertion_index - idx

    # Loop through all the options--if it exists in the buildfile's contents,
    # make sure the corresponding value is correct. If it doesn't exist,
    # add it with the correct value.
    for option, value in OPTIONS:
        index = contents.find(option)
        if index >= 0:  # Option found!
            # Check what the current value of the option is.
            str_val = str(value)

            # Chop out the line with this config option.
            prev_newline = contents.find("\n", index - arg_length)
            next_newline = contents.find("\n", index)
            current_line = contents[prev_newline + 1:next_newline - 2].strip()
            _, current_value = current_line.split("=")

            # Are they the same?
            if current_value != str_val:
                updated = pad_kv(option, value, arg_length)
                contents = insert(contents, updated, prev_newline + 1, next_newline + 1)

        else:  # Option not found! Insert it.
            # Create the new line to insert.
            to_add = pad_kv(option, value, arg_length)

            # Insert the new line, and update the insertion index.
            start_index = insertion_index + 1
            contents = insert(contents, to_add, start_index, start_index)
            insertion_index += arg_length

    # In theory--all done!
    with open("build.sh", "w") as f:
        f.write(contents)

opencv-gpu.sh

#!/bin/bash
# Installs a GPU-enabled OpenCV from the conda-forge feedstock.
# Assumes you already have Python 3 installed and the conda-forge channel on.

FEEDSTOCK_DIR=feedstock-directory
NUMPY_VER=1.12.1

# Pull down the opencv-feedstock recipe.
git clone https://github.com/conda-forge/opencv-feedstock/ ${FEEDSTOCK_DIR}
mv opencv-cuda.py ${FEEDSTOCK_DIR}/recipe && cd ${FEEDSTOCK_DIR}/recipe
python opencv-cuda.py

# Move to the parent directory and build the feedstock.
conda build --numpy ${NUMPY_VER} recipe

# Finally, to install, run:
# conda install --use-local opencv