Package cairo was not found in the pkg-config search path.

[mhulse]

MacOS Sierra:

npm install smartcrop-node --save-dev
Package cairo was not found in the pkg-config search path.
Perhaps you should add the directory containing `cairo.pc'
to the PKG_CONFIG_PATH environment variable
No package 'cairo' found
gyp: Call to './util/has_cairo_freetype.sh' returned exit status 0 while in binding.gyp. while trying to load binding.gyp
/project
└── (empty)

Just thought I would report.