GenServer that re-resolves the active theme when the OS appearance flips.
Started automatically by use Dala.App. Subscribes to Dala.Device
:appearance and, on :color_scheme_changed, calls Dala.Theme.set/1
again with whatever theme the app has registered as its "follow OS"
theme (via register_adaptive/1). If no adaptive theme is registered
the event is ignored — fixed themes stay put.
Why a GenServer
Dala.Theme.set/1 snapshots the theme into Application env at call
time; subsequent renders read from that env. To track an OS toggle
while the app is foregrounded, something has to listen for the
:appearance event and call set/1 again. A singleton process
fits — apps don't need per-screen handlers, and the framework owns
the wiring end-to-end.
Default registration
When Dala.Theme.set(Dala.Theme.Adaptive) is called, the watcher
picks Dala.Theme.Adaptive as the active follow-OS theme. To use a
custom adaptive theme module instead, call
register_adaptive(MyApp.Theme.Adaptive).
Summary
Functions
Returns a specification to start this module under a supervisor.
Register module as the app's follow-OS theme. Whenever a
:color_scheme_changed event arrives, the watcher calls
Dala.Theme.set(module) to re-resolve.
Functions
Returns a specification to start this module under a supervisor.
See Supervisor.
@spec register_adaptive(module()) :: :ok
Register module as the app's follow-OS theme. Whenever a
:color_scheme_changed event arrives, the watcher calls
Dala.Theme.set(module) to re-resolve.