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:

I believe such modularization has benefits on multiple levels:

Progress in charts


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
class description
acompnet74 WIP disable (feature) Auto-complete the current network. A very limited autorouter/assistant.
autocrop157 works buildin (feature) Reduce the board dimensions to just enclose the elements.
autoplace617 works buildin (feature) Automatically place elements.
autoroute4360 works buildin (feature) Automatically route selected or all rats. This is the original autorouter.
boardflip133 WIP
(doesn't update rtrees)
disabled (feature) All objects on the board are up-down flipped.
dbus486 WIP
(needs to install the xml?)
disabled (feature) Remote control PCB using DBUS.
diag210 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.
distalign427 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.
distaligntext466 works buildin (feature) Same as distalign, operates on text objects.
djopt2333 works buildin (feature) Various board optimization algorithms.
draw_csect536 WIP buildin (feature) Draw cross section and layer map.
draw_fab256 works buildin (feature) Draw the fab layer (for various exporters).
draw_fontsel187 WIP disable (feature) Draw the font selector GUI
export_bboard421 WIP disabled export Export breadboard
export_bom230 works buildin export Export bom (Bill of Materials)
export_dsn454 works enabled export Export specctra .dsn files
export_dxf3984 WIP disabled export Export dxf
export_fidocadj253 WIP disable export Export to FidoCadJ format (.fcd)
export_gcode2472 works buildin export Export to gcode
export_gerber996 works buildin export Export to gerber
export_ipcd356471 Work-in-progress disable export IPC-D-356 Netlist export.
export_lpr104 works buildin export Export to lpr (using export_ps to generate postscript)
export_nelma670 works buildin export Export to nelma (Numerical capacitance calculator)
export_openscad1384 WIP disabled export Export openscad
export_png1114 works buildin export Export to png, gif and jpeg
export_ps1640 works buildin export Export postscript or embedded postscript.
export_stat265 works buildin export Export various board statistics in lihata format
export_svg567 works buildin export Scalable Vector Graphics (SVG) exporter
export_test257 disabled
(work in progress)
buildin export A thin layer of code to dump exporter calls for testing the HID exporter API.
export_xy272 works buildin export Export XY centroid element data for pick & place.
fontmode174 works buildin (feature) Font editing actions.
fp_fs380 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_wget303 works buildin fp Footprint: get static (file) footprints from the web, e.g. from http://gedasymbols.org
gpmi3218 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_batch315 works buildin hid HID without GUI; read actions from stdin.
hid_gtk2_gdk1177 works buildin hid GUI: GTK2 HID with GDK software rendering.
hid_gtk2_gl1624 works buildin hid GUI: GTK2 with opengl rendering
hid_gtk3_cairo22 WIP disable hid GUI: the GTK3 HID, using cairo for rendering
hid_lesstif6982 works buildin hid GUI: the lesstif HID.
hid_remote1173 WIP disable hid Remote access HID: implement a protocol and use it to relay between a core and a remote HID implementation.
hid_srv_ws11 WIP disable hid HID server: websockets using hid_remote.
import_dsn233 works enabled import Import specctra .dsn files
import_edif3624 works buildin import Import plugin for netlists in the EDIF format.
import_hyp2919 WIP disable import Import plugin for hyperlynx geometry.
import_ltspice504 works buildin import Import the netlist and footprints from an ltspice .asc and .net pair of files
import_mentor_sch492 WIP disable import Import mentor graphics schematics from .edf netlist, using a parts conversion table.
import_mucs113 works builtin import Import lines and vias from MUCS unixplot .pl files
import_netlist136 works buildin import Import plugin for netlists in the classic pcb netlist format.
import_sch305 works buildin import Imports element and netlist data from the schematics (or some other source).
import_tinycad147 works buildin import Import the netlist and footprints from a tinycad netlist.
io_kicad3313 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_legacy944 works buildin io Export the design and elements in Kicad's legacy format.
io_lihata2187 works buildin io Load and save the design and elements in the lihata board format.
io_pcb2339 works buildin io Load and save the design and elements in the original pcb text format.
io_tedax343 works buildin import Import and export tEDAx netlists and footprints.
jostle445 works buildin (feature) Pushes lines out of the way.
lib_gensexpr6 works disabled (lib) S-expression parser lib
lib_gtk_common11467 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_config2583 works disabled (lib) hid_gtk* preferences dialog common code (regardless of gtk version)
lib_gtk_hid1395 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_func87 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.
loghid272 WIP disabled (feature) Sits between a HID (or exporter) and the core and logs all core->plugin calls made through the HID structure.
mincut904 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.
oldactions154 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)
polycombine207 works buildin (feature) The selected polygons are combined together according to the ordering of their points.
polystitch184 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.
propedit772 works buildin (feature) List and edit properties of a group of objects.
puller1888 works buildin (feature) Pull traces to minimize their length.
query1834 works buildin (feature) pcb-rnd query language: execute expressions on objects and rules for the programmed drc.
renumber308 works buildin (feature) Renumber elements (renaming them) and generate a text file for back annotation.
report1019 works buildin (feature) Report() and ReportObject() actions - print a report about design objects.
rubberband_orig853 works buildin (feature) The original rubberband code.
shand_cmd211 works buildin (feature) vi-like command shorthands (1..3 character long commands)
smartdisperse172 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.
stroke135 partially works (doesn't work with lesstif; works with the gtk hid, but there's no zoom bindings) disabled (feature) Gesture recognition with libstroke.
teardrops232 works buildin (feature) Draw teardrops on pins.
vendordrill516 works buildin (feature) Vendor drill mapping.


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