在pkg-config搜索路径中找不到包cairo.Node js安装canvas问题

我在安装在节点中安装canvas模块时遇到问题.它似乎与cairo有关我收到此错误...

npm http GET https://registry.npmjs.org/canvas
npm http 304 https://registry.npmjs.org/canvas
npm http GET https://registry.npmjs.org/nan
npm http 304 https://registry.npmjs.org/nan

> canvas@1.1.3 install /Users/plimb/Desktop/motion-therapy/node_modules/canvas
> node-gyp rebuild

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 trying to load binding.gyp
gyp ERR! configure error
gyp ERR! stack Error: `gyp` failed with exit code: 1
gyp ERR! stack     at ChildProcess.onCpExit (/usr/local/lib/node_modules/npm/node_modules/node-gyp/lib/configure.js:424:16)
gyp ERR! stack     at ChildProcess.EventEmitter.emit (events.js:98:17)
gyp ERR! stack     at Process.ChildProcess._handle.onexit (child_process.js:789:12)
gyp ERR! System Darwin 13.0.0
gyp ERR! command "node" "/usr/local/lib/node_modules/npm/node_modules/node-gyp/bin/node-gyp.js" "rebuild"
gyp ERR! cwd /Users/plimb/Desktop/motion-therapy/node_modules/canvas
gyp ERR! node -v v0.10.21
gyp ERR! node-gyp -v v0.10.10
gyp ERR! not ok
npm ERR! weird error 1 
npm ERR! not ok code 0

我不确定这一切意味着什么!非常感谢任何帮助!例如如何在pkg_config_path环境变量中使用mkdir cairo pc？