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Viktor Vaczi 92faf7c082 Add standalone core library with kimath and sexpr (Phase 2 Step 1)

Create standalone build system for KiCad's core computation libraries
that compiles without wxWidgets, targeting both native and WebAssembly.

Key additions:
- wx_shim.h: ~250 lines replacing wx utilities with standard C++
  - wxString class with Format() method
  - wxFFile for file I/O
  - wxASSERT, wxCHECK, wxFAIL_MSG macros
  - wxLog stubs
- Stub headers: wx/debug.h, wx/log.h, wx/string.h, wx/file.h, etc.
- config.h, advanced_config.h: Platform and triangulation config
- CMakeLists.txt: Builds kimath, sexpr, clipper2, rtree

Build results:
- Native: libkimath.a (1.4MB), libsexpr.a, test passes
- WASM: test_kimath.wasm (867KB), runs in Node.js

Test verifies:
- VECTOR2I, SEG, SHAPE_POLY_SET geometry operations
- S-expression parsing of .kicad_pcb format

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

2025-11-26 17:39:53 +01:00

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KiCad WebAssembly Port - Knowledge Base

Architecture Overview

KiCad is a modular EDA suite with these main components:

Project Manager (kicad/) - launches other tools
PCB Editor (pcbnew/) - board layout
Schematic Editor (eeschema/) - circuit design
3D Viewer (3d-viewer/) - 3D visualization

Shared code lives in:

common/ - shared library (kicommon), includes GUI, I/O, git, curl
libs/core/ - utilities
libs/kimath/ - geometry and math (pure C++, no deps)

Key Dependencies

Dependency	Purpose	Wasm Strategy
wxWidgets	All GUI	Keep native initially; replace with web UI later
OpenGL	2D rendering via GAL	WebGL (Emscripten handles this)
Cairo	Fallback 2D rendering	Compile with Emscripten or skip
OpenCASCADE	STEP import/export, 3D	Disable for MVP; huge (~40MB)
libcurl	PCM, update check, HTTP libs	Stub out; replace with Fetch API
libgit2	Version control integration	Stub out; optional feature
ngspice	Circuit simulation	Stub out; separate concern
nanoodbc	Database libraries	Stub out; enterprise feature
Freetype/HarfBuzz	Font rendering	Compile with Emscripten (works)
Boost	Locale, unit tests	Minimize; locale needed for nanoodbc only

Graphics Abstraction Layer (GAL)

Location: common/gal/, include/gal/

KiCad abstracts rendering through GAL with two backends:

OPENGL_GAL (common/gal/opengl/) - primary, uses GLSL shaders
CAIRO_GAL (common/gal/cairo/) - fallback, vector graphics

Key files:

include/gal/graphics_abstraction_layer.h - base interface
common/gal/opengl/opengl_gal.cpp - OpenGL implementation
common/gal/shaders/ - GLSL shaders (need ES conversion for WebGL)

For Wasm: OpenGL ES subset via Emscripten maps to WebGL. Shaders need #version removal and precision qualifiers.

File I/O System

Location: common/io/, include/io/

Plugin-based architecture supporting multiple formats:

KiCad native (.kicad_pcb, .kicad_sch)
Eagle, Altium, CADSTAR, EasyEDA imports

Key class: IO_BASE in include/io/io_base.h

Parsers are mostly pure C++ - good candidates for Wasm core.

Python Scripting

Location: scripting/, pcbnew/python/

Uses SWIG to generate CPython bindings (~3,500 lines of .i files).

For Wasm: SWIG bindings won't work. Options:

Use Emscripten's embind instead
Use Pyodide with custom FFI
Skip Python for MVP

Optional Features to Disable

These have minimal impact on core editing functionality:

Feature	CMake Area	Files
Git integration	`common/git/`	15 handler files
Network (PCM, updates)	`common/kicad_curl/`, `common/http_lib/`	~5 files
Database libraries	`common/database/`	2-3 files
STEP/3D export	`pcbnew/exporters/step/`, `plugins/3d/oce/`	Isolated
SPICE simulation	`eeschema/sim/`	Isolated subsystem

Build System Notes

Main CMake: CMakeLists.txt

Currently all deps are REQUIRED (lines 820-892). No options exist to disable curl/git/OCC.

Libraries link in common/CMakeLists.txt:316-343:

target_link_libraries( kicommon
    CURL::libcurl
    ${LIBGIT2_LIBRARIES}
    ...
)

IPC/Communication

KIWAY system (include/kiway.h, include/kiway_holder.h) handles inter-frame communication. Frames inherit from KIWAY_PLAYER.

For Wasm worker architecture: This could be adapted for message-passing between native GUI and Wasm worker.

Potential Problem Areas

Threading: KiCad uses threads for DRC, rendering. Wasm has Web Workers but different threading model.
File dialogs: wxFileDialog throughout - needs abstraction for browser File API.
Memory: Large boards can use 1GB+. Wasm has 4GB limit, but browser tabs may have lower practical limits.
Clipboard: Native clipboard integration in multiple places.
Printing: Cairo-based printing system won't work in browser.

Files of Interest for Core Extraction

Pure computation, no GUI deps - good Wasm candidates:

libs/kimath/ - all geometry code
libs/core/ - utilities
common/io/kicad/ - native format parser
pcbnew/router/ - Push & Shove routing algorithms
pcbnew/drc/ - Design Rule Check engine
eeschema/erc/ - Electrical Rule Check

Reference Paths

Component	Path
Main CMake	`CMakeLists.txt`
Common library	`common/CMakeLists.txt`
GAL system	`common/gal/`, `include/gal/`
File I/O	`common/io/`
PCB data model	`pcbnew/board.h`, `pcbnew/footprint.h`
Git integration	`common/git/`
Curl wrapper	`common/kicad_curl/`
Python bindings	`scripting/`, `pcbnew/python/swig/`
3D/STEP	`pcbnew/exporters/step/`, `3d-viewer/`

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