pcb-rnd modularization

Why bother...

I believe good software should be modular. This is especially important in the context of large software, such as CAD applications. There should be a thin core that can model the world and provide the basic operations defined on it but anything else should go in separate modules.

Fortunately PCB already had a strong infrastructure supporting this idea. It has dynamic loadable plugins and the GUI and exporters are in separate HID modules. While working on pcb-gpmi and later pcb-rnd, I added the gpmi module as a separate plugin.

In version 1.0.8 to 1.1.0 a considerable chunk of core code has been moved into core plugins. A core plugin is just a plugin that is maintained together with the core, in the same repository, still the code is somewhat detached from the core. More importantly, the user can choose, for each plugin, separately:

to compile it as a buildin (static-link it into the pcb executable)
to compile it as a plugin (dynamic-link it runtime, if the .so is installed in the plugins/ directory)
to disable the plugin, so it is not compiled at all

I believe such modularization has benefits on multiple levels:

it is possible to compile smaller, potentially faster executables by omitting features the specific user would never use anyway
in a distribution dynamic-link plugins can be distributed as separate packages providing the user with the option to decide what features to install
such plugins have to have some sort of APIs if they want to reference each other or if the code needs to reference them; such an API may not (and often did not) exist when the code is part of the core

Progress in charts

Before-after

All numbers are in SLOC and are acquired running sloccount on the given directory. While lines of code alone is not a true measure of complexity, it's a good estimation. The slices of pie charts are the major components of the pcb-rnd executable.


Before modularization: pcb-rnd version 1.0.7 Note: gpmi was already a plugin		After modularization: pcb-rnd version 1.1.3 Note: gpmi is part of the "plugins" slice

Zooming on to the plugins

total size per class

IO plugins

feature plugins

export plugins

HID plugins

import plugins

library plugins

footprint plugins

(Red means the plugin doesn't really work).

Progress in numbers

Below is a table with the summary of core plugins.

module	size [sloc]	status	configure default	class	description
acompnet	74	WIP	disable	(feature)	Auto-complete the current network. A very limited autorouter/assistant.
autocrop	157	works	buildin	(feature)	Reduce the board dimensions to just enclose the elements.
autoplace	617	works	buildin	(feature)	Automatically place elements.
autoroute	4360	works	buildin	(feature)	Automatically route selected or all rats. This is the original autorouter.
boardflip	133	WIP (doesn't update rtrees)	disabled	(feature)	All objects on the board are up-down flipped.
dbus	486	WIP (needs to install the xml?)	disabled	(feature)	Remote control PCB using DBUS.
diag	210	works	disabled	(feature)	Actions for pcb-rnd core diagnostics, intended for developers. These are not in core because end users normally don't need these. As a plugin, due to dynamic loading, it can be dropped on an existing pcb-rnd installation with minimal risk of scaring away a reproducible bug.
distalign	427	works	buildin	(feature)	Introducing Align() and Distribute(), which work much like the similarly named functions in Visio. Given that PCB does not have the concept of "first selected object" to draw on, the reference points can be selected by arguments.
distaligntext	466	works	buildin	(feature)	Same as distalign, operates on text objects.
djopt	2333	works	buildin	(feature)	Various board optimization algorithms.
draw_csect	536	WIP	buildin	(feature)	Draw cross section and layer map.
draw_fab	256	works	buildin	(feature)	Draw the fab layer (for various exporters).
draw_fontsel	187	WIP	disable	(feature)	Draw the font selector GUI
export_bboard	421	WIP	disabled	export	Export breadboard
export_bom	230	works	buildin	export	Export bom (Bill of Materials)
export_dsn	454	works	enabled	export	Export specctra .dsn files
export_dxf	3984	WIP	disabled	export	Export dxf
export_fidocadj	253	WIP	disable	export	Export to FidoCadJ format (.fcd)
export_gcode	2472	works	buildin	export	Export to gcode
export_gerber	996	works	buildin	export	Export to gerber
export_ipcd356	471	Work-in-progress	disable	export	IPC-D-356 Netlist export.
export_lpr	104	works	buildin	export	Export to lpr (using export_ps to generate postscript)
export_nelma	670	works	buildin	export	Export to nelma (Numerical capacitance calculator)
export_openscad	1384	WIP	disabled	export	Export openscad
export_png	1114	works	buildin	export	Export to png, gif and jpeg
export_ps	1640	works	buildin	export	Export postscript or embedded postscript.
export_stat	265	works	buildin	export	Export various board statistics in lihata format
export_svg	567	works	buildin	export	Scalable Vector Graphics (SVG) exporter
export_test	257	disabled (work in progress)	buildin	export	A thin layer of code to dump exporter calls for testing the HID exporter API.
export_xy	272	works	buildin	export	Export XY centroid element data for pick & place.
fontmode	174	works	buildin	(feature)	Font editing actions.
fp_fs	380	works	buildin	fp	Footprint: file system based implementation. Used to be called Newlib: load footprints from directories. Run external processes for the parametric footprints.
fp_wget	303	works	buildin	fp	Footprint: get static (file) footprints from the web, e.g. from http://gedasymbols.org
gpmi	3218	works	buildin (if gpmi is installed)	(feature)	Scriptable plugin system with about 10 scripting languages supported and dynamic load/unload of scripts that can manipulate the GUI, the board, can implement exporters, etc.
hid_batch	315	works	buildin	hid	HID without GUI; read actions from stdin.
hid_gtk2_gdk	1177	works	buildin	hid	GUI: GTK2 HID with GDK software rendering.
hid_gtk2_gl	1624	works	buildin	hid	GUI: GTK2 with opengl rendering
hid_gtk3_cairo	22	WIP	disable	hid	GUI: the GTK3 HID, using cairo for rendering
hid_lesstif	6982	works	buildin	hid	GUI: the lesstif HID.
hid_remote	1173	WIP	disable	hid	Remote access HID: implement a protocol and use it to relay between a core and a remote HID implementation.
hid_srv_ws	11	WIP	disable	hid	HID server: websockets using hid_remote.
import_dsn	233	works	enabled	import	Import specctra .dsn files
import_edif	3624	works	buildin	import	Import plugin for netlists in the EDIF format.
import_hyp	2919	WIP	disable	import	Import plugin for hyperlynx geometry.
import_ltspice	504	works	buildin	import	Import the netlist and footprints from an ltspice .asc and .net pair of files
import_mentor_sch	492	WIP	disable	import	Import mentor graphics schematics from .edf netlist, using a parts conversion table.
import_mucs	113	works	builtin	import	Import lines and vias from MUCS unixplot .pl files
import_netlist	136	works	buildin	import	Import plugin for netlists in the classic pcb netlist format.
import_sch	305	works	buildin	import	Imports element and netlist data from the schematics (or some other source).
import_tinycad	147	works	buildin	import	Import the netlist and footprints from a tinycad netlist.
io_kicad	3313	works	buildin	io	Load and save the design and elements in Kicad's s-expression format - this is the new, currently preferred format in Kicad.
io_kicad_legacy	944	works	buildin	io	Export the design and elements in Kicad's legacy format.
io_lihata	2187	works	buildin	io	Load and save the design and elements in the lihata board format.
io_pcb	2339	works	buildin	io	Load and save the design and elements in the original pcb text format.
io_tedax	343	works	buildin	import	Import and export tEDAx netlists and footprints.
jostle	445	works	buildin	(feature)	Pushes lines out of the way.
lib_gensexpr	6	works	disabled	(lib)	S-expression parser lib
lib_gtk_common	11467	works	disabled	(lib)	hid_gtk* common code (regardless of gtk version or drawing mechanism: for both gtk2 and gtk3 and for both sw rendering and gl)
lib_gtk_config	2583	works	disabled	(lib)	hid_gtk* preferences dialog common code (regardless of gtk version)
lib_gtk_hid	1395	works	disabled	(lib)	Generic gtk HID implementation, independent of GTK version (2 vs. 3) and rendering engine. Mostly a dispatcher that fills in all the glue to connect the parts. An actual gtk HID implementation may use this lib or replace parts of it or the whole with local implementation.
lib_legacy_func	87	works	buildin	(lib)	Random collection of old/obsolete (legacy) functions. 3rd party plugins may depend on them. This module implements C functions and variables and does not register actions or flags.
loghid	272	WIP	disabled	(feature)	Sits between a HID (or exporter) and the core and logs all core->plugin calls made through the HID structure.
mincut	904	works	buildin	(feature)	Use the minimal cut algorithm to indicate shorts: instead of highlighting two random pins/pads, try to highlight the least number of objects that connect the two networks.
oldactions	154	works	disabled	(feature)	Random collection of old/obsolete actions. Bell(): audible feedback; DumpLibrary(): print footprint library on stdout; a set of debug actions useful for writing pcb scripts: Debug(), DebugXY(), Return(). Old plugin actions to toggle or set settings that are now accessible via the unified config system (vendordrill, djopt)
polycombine	207	works	buildin	(feature)	The selected polygons are combined together according to the ordering of their points.
polystitch	184	segfaults	disable	(feature)	The polygon under the cursor (based on closest-corner) is stitched together with the polygon surrounding it on the same layer. Use with pstoedit conversions where there's a "hole" in the shape - select the hole.
propedit	772	works	buildin	(feature)	List and edit properties of a group of objects.
puller	1888	works	buildin	(feature)	Pull traces to minimize their length.
query	1834	works	buildin	(feature)	pcb-rnd query language: execute expressions on objects and rules for the programmed drc.
renumber	308	works	buildin	(feature)	Renumber elements (renaming them) and generate a text file for back annotation.
report	1019	works	buildin	(feature)	Report() and ReportObject() actions - print a report about design objects.
rubberband_orig	853	works	buildin	(feature)	The original rubberband code.
shand_cmd	211	works	buildin	(feature)	vi-like command shorthands (1..3 character long commands)
smartdisperse	172	works	buildin	(feature)	Improve the initial dispersion of elements by choosing an order based on the netlist, rather than the arbitrary element order. This isn't the same as a global autoplace, it's more of a linear autoplace. It might make some useful local groupings. For example, you should not have to chase all over the board to find the resistor that goes with a given LED.
stroke	135	partially works (doesn't work with lesstif; works with the gtk hid, but there's no zoom bindings)	disabled	(feature)	Gesture recognition with libstroke.
teardrops	232	works	buildin	(feature)	Draw teardrops on pins.
vendordrill	516	works	buildin	(feature)	Vendor drill mapping.

Classes

Each plugin implements a class (rarely a set of classes). Classes are:

name	description
(feature)	random features directly accessible for the user, usually actions
(lib)	support code library for other plugins (core doesn't depend on these); functionality not directly accessible for the user but other plugins may depend on it
hid	Human Interface Device: interactive user interface, usually GUI
import	load alien formats into the design space
export	save (parts of) the design space in alien formats
fp	footprint (element) library implementation
io	native file format (save & load) implementation