# pcb Plugins

pcb has a plug-in mechanism that allows developers to add or modify its functionality. Plugins can add pcb actions, hook into the GUI HIDs, create new exporters, and more. For a tutorial on the basics of writing and installing a pluging, see the hello world example on the pcb Developer Introduction page. This page will discuss how plugins interact with the pcb system.

## Plugin Mechanics

pcb plugins are essentially shared libraries that pcb will load at run-time. Because of this, they can be written in just about any language that can be compiled into a shared library. I haven't verified anything other than C and C++, but it ought to be possible. If you've successfully written a plugin in another language, let me know!

At runtime, pcb scans several directories for .so/.dll files (see src/common/hidinit.c:hid_load_dir). These include the exec prefix and the users personal preferences directory (~/.pcb). The exec_prefix is currently reserved for system plugins. Inside the personal pref directory should be a directory called “plugins”. User plugins should be located in this directory.

If pcb finds a .so/.dll file, it opens it and looks for a couple of symbols: “hid_<file basename>_init” and “pcb_plugin_init”. If it finds one, it executes it as a function. These functions are responsible for registering the code they represent with pcb.

### Registration

### HID Structures

## Plugin Resources

### Handy Plugin Template

### Plugin Repositories

https://github.com/bert/pcb-plugins

https://ljh4timm.home.xs4all.nl/gaf/dox_pcb-plugins/index.html

### List of Plugins

- Polygon Stitcher, by DJ
- Ben Mode photos for the PNG hid, by DJ
- Find Rat, by DJ
- Board Flip, by DJ
- Renumber Block, by DJ
- Teardrops, by DJ
- https://github.com/bert/pcb-plugins git repo with many plugins
- sed rename, by bgamari
- Debug Window, by Chad Parker