Build instructions

First of all, in most cases you don't need to build the font from scratch. There is always a ttf-file ready at fonts. But if you think you need to build the font, here is a quick instruction (I know that the original repository includes some instructions but I had a little trouble with them myself):

1. At the moment Python 2.7 is required
2. As the image files provided need to be compressed, either zopflipng or optipng is required.
   On Fedora both zopflipng and optipng is available. You can install it with sudo dnf install zopflipng (or optipng).
   On Ubuntu only optipng seems to be working (at least I didn't find zopflipng when using Ubuntu 16.04 running in Windows 10). You can install it with sudo apt install optipng.
3. Another package you'll need is cairo.
4. You'll need fonttools and nototools. At least on Ubuntu installing fonttools with apt didn't work for me. I recommend installing it with pip.
5. When everything is ready, try running make -j (inside the root folder of this repository). Note that this has little to no output
6. Once the build process is finished (it might take some minutes to build the font), there should be a file called NotoColorEmoji.ttf. This is the font you just created 😁