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Keep MIDI input alive with the screen off / app backgrounded (v0.21.1)

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MIDI (and the MIDI clock) were started in onStart and stopped in onStop, so
turning the screen off — which drives the Activity to onStop — closed the MIDI
ports and dropped controller input. Move their lifecycle to onCreate/onDestroy so
input persists for the Activity's whole lifetime; onStop keeps only the project
autosave. The audio engine already runs a continuous output stream via the started
PlaybackService, which keeps the process alive (verified at PERSISTENT_SERVICE_ADJ
when backgrounded) to receive events with the screen off. USB MIDI needs no runtime
permission, so it works unconditionally.

Trade-off: the controller stays claimed by the app while backgrounded, and is
released only when the Activity is torn down (task removed / finishing).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
This commit is contained in:
Reactorcoremeltdown
2026-07-22 23:52:14 +02:00
parent 7296a3a72b
commit 924b84a4d5
2 changed files with 18 additions and 7 deletions
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4
app/build.gradle.kts
View File

@@ -22,8 +22,8 @@ android {
// (android.media.midi) and AAudio low-latency audio we rely on. // (android.media.midi) and AAudio low-latency audio we rely on.
minSdk = 26 minSdk = 26
targetSdk = 34 targetSdk = 34
versionCode = 47 versionCode = 48
versionName = "0.21.0" versionName = "0.21.1"
// We provide our own instrumentation runner if/when tests are added. // We provide our own instrumentation runner if/when tests are added.
testInstrumentationRunner = "androidx.test.runner.AndroidJUnitRunner" testInstrumentationRunner = "androidx.test.runner.AndroidJUnitRunner"

21
app/src/main/java/space/rcmd/android/sizzle/MainActivity.kt
View File

@@ -75,10 +75,13 @@ class MainActivity : ComponentActivity() {
SizzleAppUi(viewModel) SizzleAppUi(viewModel)
} }
} }
}
override fun onStart() { // Start MIDI listening (USB + BLE) and the MIDI clock here — bound to the
super.onStart() // Activity's WHOLE lifetime (onCreate..onDestroy), not onStart/onStop — so a
// connected controller keeps driving the app while the screen is off. The
// audio engine already runs a continuous output stream via the started
// PlaybackService, which keeps the process alive to receive those events in
// the background; closing the ports on onStop was the only reason input died.
midi.start() midi.start()
app.midiClock.start() app.midiClock.start()
} }
@@ -93,11 +96,19 @@ class MainActivity : ComponentActivity() {
override fun onStop() { override fun onStop() {
// Autosave the project whenever we leave the foreground, so a later // Autosave the project whenever we leave the foreground, so a later
// system-kill (or crash) resumes from here on next launch. // system-kill (or crash) resumes from here on next launch. MIDI is
// deliberately NOT stopped here (see onCreate / onDestroy) so controllers
// keep working with the screen off or the app backgrounded.
app.projectStore.save(app.project) app.projectStore.save(app.project)
super.onStop()
}
override fun onDestroy() {
// Release MIDI only when the Activity is actually torn down (task removed or
// finishing), not merely backgrounded / screen-off.
midi.stop() midi.stop()
app.midiClock.stop() app.midiClock.stop()
super.onStop() super.onDestroy()
} }
// ---- Hardware input forwarding ---- // ---- Hardware input forwarding ----