坑
安装指南在这，但是有坑。。
https://github.com/Automattic/node-canvas/wiki/Installation---OSX
1、安装pkg-config
$ curl http://pkgconfig.freedesktop.org/releases/pkg-config-0.28.tar.gz -o pkgconfig.tgz
$ tar -zxf pkgconfig.tgz && cd pkg-config-0.28
$ ./configure && make install问题1：安装包文件夹别放在名字有空格的文件夹里，读不出来
问题2：install: /usr/local/bin/pkg-config: Permission denied
这里不是说用sudo 就行了，是说/usr/local/bin/有问题
运行 sudo chmod 777 /usr/local/bin/
ps:
$ ./configure && make install这句话最好分开写，记得加sudo
$ ./configure这句话没有用的时候用：
sudo ./configure --with-internal-glib && make install
然后出现一批make[5]: Nothing to be done for [***]就成功了
2、安装pixman
按照他的来
$ curl http://www.cairographics.org/releases/pixman-0.30.0.tar.gz -o pixman.tar.gz
$ tar -zxf pixman.tar.gz && cd pixman-0.30.0/
$ ./configure --prefix=/usr/local --disable-dependency-tracking
$ make install安装0.30.0,是个坑爹的选择，出现了clang 编译错误，好像解决就要安装homebrew，但是仍然完全不知道如何解决。。
冒险安装了最新版本0.34.0 问题解决，目前没有不良反应。。
3、安装cairo
$ curl http://cairographics.org/releases/cairo-1.12.18.tar.xz -o cairo.tar.xz
$ tar -xf cairo.tar.xz && cd cairo-1.12.18
$ ./configure --prefix=/usr/local --disable-dependency-tracking
$ make install考虑到pixman用的最新版本，这个我也下了最新的cairo-1.14.6
问题1：configure: error: recommended PNG functions feature could not be enabled
这个官网上有解决方案：http://ethan.tira-thompson.com/Mac_OS_X_Ports.html 安装这个库
为了保险运行了下面两句话：
$ export PKG_CONFIG_PATH=/usr/local/lib/pkgconfig
$export PKG_CONFIG_PATH=/usr/local/lib/pkgconfig:/opt/X11/lib/pkgconfig然后sudo make install成功
4、安装canvas
到要安装canvas的文件夹npm ，失败：
> canvas@1.3.10 install******/node_modules/canvas
> node-gyp rebuild
SOLINK_MODULE(target) Release/canvas-postbuild.node
CXX(target) Release/obj.target/canvas/src/Canvas.o
In file included from ../src/Canvas.cc:20:
../src/JPEGStream.h:10:10: fatal error: 'jpeglib.h' file not found
#include <jpeglib.h>
^
1 error generated.
make: *** [Release/obj.target/canvas/src/Canvas.o] Error 1
gyp ERR! build error
gyp ERR! stack Error: `make` failed with exit code: 2
gyp ERR! stack at ChildProcess.onExit (/usr/local/lib/node_modules/npm/node_modules/node-gyp/lib/build.js:270:23)
gyp ERR! stack at emitTwo (events.js:87:13)
gyp ERR! stack at ChildProcess.emit (events.js:172:7)
gyp ERR! stack at Process.ChildProcess._handle.onexit (internal/child_process.js:200:12)
gyp ERR! System Darwin 15.3.0
gyp ERR! command "/usr/local/bin/node" "/usr/local/lib/node_modules/npm/node_modules/node-gyp/bin/node-gyp.js" "rebuild"
gyp ERR! cwd /Users/fengyujia/Documents/My Code/zc_core/node_modules/canvas
gyp ERR! node -v v5.3.0
gyp ERR! node-gyp -v v3.0.3
gyp ERR! not ok
npm ERR! Darwin 15.3.0
npm ERR! argv "/usr/local/bin/node" "/usr/local/bin/npm" "install" "canvas"
npm ERR! node v5.3.0
npm ERR! npm v3.3.12
npm ERR! code ELIFECYCLE
npm ERR! canvas@1.3.10 install: `node-gyp rebuild`
npm ERR! Exit status 1
npm ERR!
npm ERR! Failed at the canvas@1.3.10 install script 'node-gyp rebuild'.
npm ERR! Make sure you have the latest version of node.js and npm installed.
npm ERR! If you do, this is most likely a problem with the canvas package,
npm ERR! not with npm itself.
npm ERR! Tell the author that this fails on your system:
npm ERR! node-gyp rebuild
npm ERR! You can get their info via:
npm ERR! npm owner ls canvas
npm ERR! There is likely additional logging output above.
npm ERR! Please include the following file with any support request:
npm ERR! ******/npm-debug.log
解决办法看这：https://github.com/Automattic/node-canvas/issues/225
按着他们的讨论一路执行下去，最后的那句
xcode-select --install
有效（不知道前面的命令有没有影响）
安装完这个后就可以npm install canvas了