anchor.diff:      "-DOPENCV_ENABLE_NONFREE=${printEnabled enableUnfree}"
       "-DBUILD_TESTS=OFF"
       "-DBUILD_PERF_TESTS=OFF"
  +    "-DBUILD_DOCS=${printEnabled enableDocs}"
       (opencvFlag "IPP" enableIpp)
       (opencvFlag "TIFF" enableTIFF)
       (opencvFlag "JASPER" enableJPEG2K)
  
positive.code: stdenv.mkDerivation rec {
    name = "opencv-${version}";
    inherit version src;
  
    patches = [
      # Fix for: https://github.com/opencv/opencv/issues/10474
      (fetchpatch {
        url = "https://github.com/opencv/opencv/commit/ea5a3e557f93844fdb5e54e3e8acfc5f61c6fd9f.patch";
        sha256 = "1w7jmqlrx73ydh9jjsnnic5xz8r04kxbjpzkcfyb91v3az9132r1";
      })
    ];
  
    postUnpack = lib.optionalString buildContrib ''
      cp --no-preserve=mode -r "${contribSrc}/modules" "$NIX_BUILD_TOP/opencv_contrib"
  
negative.code: }:
  
  let
    version = "3.4.1";
  
    src = fetchFromGitHub {
      owner  = "opencv";
      repo   = "opencv";
      rev    = version;
      sha256 = "08yahgf427d2qbs2mw02xww6bv5yjkfc1hihihh7fhqgfz0jnj1h";
    };
  
    contribSrc = fetchFromGitHub {
      owner  = "opencv";
      repo   = "opencv_contrib";
      rev    = version;
      sha256 = "00x1x53qv2pnc7i56244b5nf44wm2mp77hj486i5697r6hikk8n3";
    };
  
    # Contrib must be built in order to enable Tesseract support:
  