General information

This is an example of ADG usage scenario: an end-point for generating dynamic drawings solely based on the OpenResty webserver.

OpenResty is an NGINX webserver flavour with integrated Lua support for stellar performances. This makes it a perfect fit for automatic drawing generation.

Installation

You should already have OpenResty installed somewhere in your system. Also, you must have at least installed the runtime and development packages of the following projects:

• cairo
• pango
• gobject-introspection

On desktop system, these dependencies are usually already installed but on headless servers some manual intervention is likely needed. Here are the steps needed on a typical Debian 9 server:

# Install the required dependencies on Debian 9
apt install build-essential \
            gobject-introspection libgirepository1.0-dev \
            libcairo2-dev libpango1.0-dev
# For more recent releases, we install ninja and meson with `pip3`
apt install python3-pip
pip3 install meson ninja

On other systems, something similar would likely be required. Once every needed dependency is installed, we can build everything else inside a local folder: no root privileges are needed here!

mkdir my-adg-app
cd my-adg-app
git clone https://github.com/pavouk/lgi/
git clone https://github.com/ntd/adg
git clone https://github.com/ntd/adg-openresty
cd adg-openresty
# Customize the environment to match your system
vi helpers/env.conf
helpers/build-lgi ../lgi
helpers/build-adg ../adg

Once everything has been built, you can start or stop the adg-openresty service by using the helper script adg-openresty:

# To start the service
helpers/adg-openresty start
# To stop the service
helpers/adg-openresty stop

Once the service is successfully started, you can see the results on http://localhost:2784/piston.png. The default piston should be something similar to the following drawing:

You can change any variable by passing custom settings as GET arguments. The list of possible variable names, together with their fallback values, is exposed in piston.lua, function DATA(). For example, you should get the following piston with http://localhost:2784/piston.png?A=45&B=25&DHOLE=8&DGROOVE=&D1=13&D3=14&LD3=10&D6=16:

License

This project is licensed under the terms of the MIT license.