Replace the per-key dropdown UI (MapChoiceControl) with a Cairo-rendered
keyboard canvas where users can paint colors directly onto keys.
Editor (lib/solaar/ui/perkey/):
- Cairo DrawingArea renders cells from a Layout dataclass; bound cells
take their painted color, unset cells show a diagonal hash whose base
color matches the device's rgb_zone_* setting.
- Tools: brush, drag-rectangle, flood-fill (4-adjacent, Paint-style),
and a directional gradient (line A->B projected across the matrix
with cells past the endpoints clamped to the endpoint colors).
- GradientSwatch is the single source of truth for the gradient's two
colors; the canvas reads from it on each gradient stroke.
- Palette: GTK ColorButton plus an unset toggle that paints the
"no change" sentinel (-1).
- PerKeyEditorDialog auto-sizes from the canvas's size_request, so a
104-key keyboard opens wide and a 8-LED mouse opens compact.
- Editor consumes only a narrow PerKeyColorSink protocol; never imports
from lib/logitech_receiver, preserving the FE/BE seam.
- Per-device palette state (active + previous color) persists via the
existing persister under a _palette: prefixed key.
Layouts:
- ANSI 104-key full-size and TKL keyboard layouts.
- G502 X family mouse layout (zones 1-8 -> labels A-H).
- Generic registry: register_layout(feature, matcher, layout). A
_name_contains() helper builds case-insensitive substring matchers
against device codename / name. Unknown devices fall back to a flat
strip of all reported zones.
Validator (open value space):
- New Range dataclass and MapRangeValidator extending Validator
directly (kind=MAP_CHOICE for dispatch compatibility). Replaces the
ChoicesMapValidator on PerKeyLighting -- the named-color universe
(COLORSPLUS) was rejecting any picker color outside its ~20 entries.
Other MAP_CHOICE settings are untouched.
Integration:
- Setting base gains an editor_class string attribute. config_panel's
_create_sbox resolves it via importlib before the kind dispatch, so
PerKeyLighting routes to the new editor without a new Kind value.
- CLI gains a hex/dec parser for open-value MAP_CHOICE settings:
solaar config <dev> per-key-lighting A 0xFF00FF
- Diversion rule editor skips Range-valued MAP_CHOICE settings'
value-selector instead of crashing on the open value space.
- pycairo declared in install_requires; transitively present on most
systems but now explicit for pip-from-source installs.
Tests in test_setting_templates.py updated for the new validator.