pl_editor (drawing-sheet editor) WASM port — design notes

Goal

Bring up KiCad's pagelayout_editor sub-app (also known as pl_editor, the drawing-sheet editor) in the browser, to the same "boots, canvas visible, partially usable in-session" level as pcbnew. Persistence across sessions not required.

Approach

Mirrors the in-tree pattern that pcbnew/calculator/eeschema use: gate WASM differences behind if( EMSCRIPTEN ) blocks inside the upstream pagelayout_editor/CMakeLists.txt, keeping a single source of truth for the build alongside KiCad's existing platform conditionals (if( WIN32 ), if( APPLE )).

(An earlier iteration tried an out-of-tree CMake wrapper to keep the kicad submodule bit-for-bit upstream. It worked, but diverged from the team norm — every other WASM-ported app modifies kicad. We converged to the team pattern; the only kicad-side cost is a ~80-line patch in this app's CMakeLists.txt, all WASM-conditional.)

Changes (see kicad.patch + root.patch + wxwidgets.patch)

kicad submodule

kicad/pagelayout_editor/CMakeLists.txt — mirrors pcbnew's WASM static-linking pattern:
- Drop BUILD_KIWAY_DLL from single_top.cpp and pl_editor.cpp compile defs on EMSCRIPTEN (browser can't dlopen a .kiface shared library).
- Split pl_editor_kiface into an OBJECT library (pl_editor_kiface_objects) + an empty MODULE; lets the same compiled objects be linked statically into the exe on WASM and dynamically into the .kiface module on native.
- On EMSCRIPTEN, link pl_editor directly against PL_EDITOR_KIFACE_LIBRARIES with LINKER:--allow-multiple-definition (handles wxWidgets/nanosvg duplicate symbols, same as pcbnew).
kicad/pagelayout_editor/navlib/CMakeLists.txt — for EMSCRIPTEN, replace the real 3Dconnexion SpaceMouse plugin sources with wasm/stubs/nl_pl_editor_plugin_stub.cpp (no USB hardware in the browser).

Root repo

wasm/stubs/nl_pl_editor_plugin_stub.cpp — no-op NL_PL_EDITOR_PLUGIN ctor/dtor + SetCanvas/SetFocus, mirroring nl_pcbnew_plugin_stub.cpp.
scripts/kicad/build-pl_editor.sh — thin wrapper around build-kicad-target.sh pl_editor.
scripts/kicad/build-kicad-target.sh — adds pl_editor to the case (uses upstream target name pl_editor, source subdir pagelayout_editor).
docker/build.sh — adds pl_editor to the unified app dispatch (valid apps + all loop + kicad_subdir_for).
tests/apps/kicad/pl_editor.html — browser shell; preRun creates /home/kicad and FS.chdir there so file dialogs land somewhere friendly instead of MEMFS root.
tests/scripts/setup-kicad-wasm.sh — copy_app pl_editor added to the existing list.
tests/e2e/filedialog-folder-nav.spec.ts — regression test for the wxFileDialog folder-navigation fix.

wxwidgets submodule (file dialog usability fixes)

These were discovered while bringing up pl_editor's file dialog but apply to any wxWidgets-WASM app:

wxwidgets/src/generic/filedlgg.cpp — wxGenericFileDialog::OnOk now navigates into the selected entry when it's a directory instead of closing the dialog and surfacing the folder path to the caller as if it were a file. Without this, KiCad's "Open Drawing Sheet" produced "Unable to load /dev file" when the user selected /dev (a directory in MEMFS).
wxwidgets/src/wasm/mouse.cpp — stateful double-click detection. EmscriptenMouseEvent has no click-count field, so wxEVT_LEFT_DCLICK literally never fired in the WASM build — breaking EVT_LIST_ITEM_ACTIVATED on every listctrl. Now two MOUSEDOWNs of the same button within 500ms emit DCLICK.

Build & verify

./docker/build.sh pl_editor
./tests/scripts/setup-kicad-wasm.sh
# serve tests/apps/kicad and open pl_editor.html

Expect: window opens, canvas renders, File > Open / Save As dialogs work (folder navigation via single-click + Enter, single-click + OK, or double-click). Dialog lands at /home/kicad by default.

Known limitations

No persistent storage (MEMFS only); files vanish on tab close.
No keyboard accelerator for "navigate to parent directory" beyond the up-arrow button + ".." entry.
Drawing-sheet-specific tooling beyond basic edit/save is untested (out of MVP scope).

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