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	75	WIP	disable	feature	Auto-complete the current network. A very limited autorouter/assistant.
autocrop	158	works	buildin	feature	Reduce the board dimensions to just enclose the elements.
autoplace	618	works	buildin	feature	Automatically place elements.
autoroute	4361	works	buildin	feature	Automatically route selected or all rats. This is the original autorouter.
boardflip	221	(doesn't update rtrees)	buildin	feature	All objects on the board are up-down flipped.
dbus	487	WIP (needs to install the xml?)	disable	feature	Remote control PCB using DBUS.
diag	211	works	disable	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	428	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	467	works	buildin	feature	Same as distalign, operates on text objects.
djopt	2334	works	buildin	feature	Various board optimization algorithms.
draw_csect	537	WIP	disable	feature	Draw cross section and layer map.
draw_fab	258	works	buildin	feature	Draw the fab layer (for various exporters).
draw_fontsel	188	WIP	disable	feature	Draw the font selector GUI
export_bboard	422	WIP	disable-all	export	Export breadboard
export_bom	234	works	buildin	export	Export bom (Bill of Materials)
export_dsn	455	works	buildin	export	Export specctra .dsn files
export_dxf	3985	WIP	disable-all	export	Export dxf
export_fidocadj	257	WIP	disable-all	export	Export to FidoCadJ format (.fcd)
export_gcode	2476	works	buildin	export	Export to gcode
export_gerber	1000	works	buildin	export	Export to gerber
export_ipcd356	472	Work-in-progress	disable-all	export	IPC-D-356 Netlist export.
export_lpr	108	works	buildin	export	Export to lpr (using export_ps to generate postscript)
export_nelma	674	works	buildin	export	Export to nelma (Numerical capacitance calculator)
export_openscad	1385	WIP	disable-all	export	Export openscad
export_png	1118	works	buildin	export	Export to png, gif and jpeg
export_ps	1645	works	buildin	export	Export postscript or embedded postscript.
export_stat	269	works	buildin	export	Export various board statistics in lihata format
export_svg	571	works	buildin	export	Scalable Vector Graphics (SVG) exporter
export_test	261	WIP	disable	export	A thin layer of code to dump exporter calls for testing the HID exporter API.
export_xy	276	works	buildin	export	Export XY centroid element data for pick & place.
fontmode	266	works	buildin	feature	Font editing actions.
fp_fs	389	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	570	works	buildin	fp	Footprint: get static (file) footprints from the web, e.g. from http://gedasymbols.org
gpmi	3218	works	buildin	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	319	works	buildin	hid	HID without GUI: read actions from stdin.
hid_gtk2_gdk	1203	works	buildin	hid	GUI: GTK2 HID with GDK software rendering.
hid_gtk2_gl	1638	works	buildin	hid	GUI: GTK2 with opengl rendering
hid_gtk3_cairo	1005	WIP	disable-all	hid	GUI: the GTK3 HID, using cairo for rendering
hid_lesstif	6994	works	buildin	hid	GUI: the lesstif HID.
hid_remote	1174	WIP	disable-all	hid	Remote access HID: implement a protocol and use it to relay between a core and a remote HID implementation.
hid_srv_ws	15	WIP	disable-all	hid	HID server: websockets using hid_remote.
import_dsn	238	works	buildin	import	Import specctra .dsn files
import_edif	3625	works	buildin	import	Import plugin for netlists in the EDIF format.
import_ltspice	505	works	buildin	import	Import the netlist and footprints from an ltspice .asc and .net pair of files
import_mentor_sch	493	works	buildin	import	Import Mentor Graphics Design Capture from flattened .edf netlist, using a parts conversion table.
import_mucs	114	works	buildin	import	Import lines and vias from MUCS unixplot .pl files
import_netlist	137	works	buildin	import	Import plugin for netlists in the classic pcb netlist format.
import_sch	306	works	buildin	import	Imports element and netlist data from the schematics (or some other source).
import_tinycad	148	works	buildin	import	Import the netlist and footprints from a tinycad netlist.
io_eagle	940	WIP	disable-all	io	Load the design from eagle's xml format.
io_hyp	3278	works	buildin	import	Import plugin for hyperlynx geometry (no polygons yet).
io_kicad	3179	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	945	works	buildin	io	Export the design and elements in Kicad's legacy format.
io_lihata	2268	works	buildin	io	Load and save the design and elements in the lihata board format.
io_pcb	2349	works	buildin	io	Load and save the design and elements in the original pcb text format.
io_tedax	686	works	buildin	import	Import and export tEDAx netlists and footprints.
jostle	446	works	buildin	feature	Pushes lines out of the way.
lib_gensexpr	10	works	disable-all	lib	S-expression parser lib
lib_gtk_common	11405	works	disable-all	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	2679	works	disable-all	lib	hid_gtk* preferences dialog common code (regardless of gtk version)
lib_gtk_hid	1380	works	disable-all	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	91	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	273	WIP	disable	feature	Sits between a HID (or exporter) and the core and logs all core->plugin calls made through the HID structure.
mincut	905	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	155	works	disable	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	208	works	buildin	feature	The selected polygons are combined together according to the ordering of their points.
polystitch	185	segfaults	disable-all	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	773	works	buildin	feature	List and edit properties of a group of objects.
puller	1889	works	buildin	feature	Pull traces to minimize their length.
query	1835	works	buildin	feature	pcb-rnd query language: execute expressions on objects and rules for the programmed drc.
renumber	309	works	buildin	feature	Renumber elements (renaming them) and generate a text file for back annotation.
report	1021	works	buildin	feature	Report() and ReportObject() actions - print a report about design objects.
rubberband_orig	904	works	buildin	feature	The original rubberband code.
shand_cmd	212	works	buildin	feature	vi-like command shorthands (1..3 character long commands)
smartdisperse	173	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	139	partially works (doesn't work with lesstif, works with the gtk hid, but there's no zoom bindings)	disable	feature	Gesture recognition with libstroke.
teardrops	233	works	buildin	feature	Draw teardrops on pins.
vendordrill	517	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

Plugin dependency map

pcb-rnd plugin dependency graph