86 lines
2.9 KiB
Kotlin
86 lines
2.9 KiB
Kotlin
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package com.example.jnicpp.bowling
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import androidx.lifecycle.ViewModel
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import androidx.lifecycle.viewModelScope
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import kotlinx.coroutines.Job
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import kotlinx.coroutines.delay
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import kotlinx.coroutines.flow.MutableSharedFlow
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import kotlinx.coroutines.flow.MutableStateFlow
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import kotlinx.coroutines.flow.SharedFlow
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import kotlinx.coroutines.flow.StateFlow
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import kotlinx.coroutines.flow.asSharedFlow
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import kotlinx.coroutines.flow.asStateFlow
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import kotlinx.coroutines.isActive
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import kotlinx.coroutines.launch
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/**
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* Holds camera/recording UI state so it survives configuration changes and
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* so the state machine lives outside the Activity. This class knows nothing
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* about CameraX or ML Kit APIs directly -- [BowlingCameraActivity] and
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* [CameraXController] report events into it, and the UI observes it back
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* out. That keeps this class trivially unit-testable (no Android camera
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* framework involved).
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*/
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class CameraViewModel : ViewModel() {
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sealed interface RecordingState {
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data object Idle : RecordingState
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data object Starting : RecordingState
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data class Recording(val elapsedSeconds: Long) : RecordingState
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}
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private val _recordingState = MutableStateFlow<RecordingState>(RecordingState.Idle)
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val recordingState: StateFlow<RecordingState> = _recordingState.asStateFlow()
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private val _permissionsGranted = MutableStateFlow(false)
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val permissionsGranted: StateFlow<Boolean> = _permissionsGranted.asStateFlow()
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// One-shot user-facing error messages (camera unavailable, detector
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// failure, storage failure, ...). SharedFlow, not StateFlow, so the same
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// error doesn't get replayed and re-shown after a config change.
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private val _errorEvents = MutableSharedFlow<String>(extraBufferCapacity = 4)
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val errorEvents: SharedFlow<String> = _errorEvents.asSharedFlow()
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private var timerJob: Job? = null
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fun onPermissionsResult(granted: Boolean) {
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_permissionsGranted.value = granted
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}
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fun onRecordingStarting() {
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_recordingState.value = RecordingState.Starting
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}
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fun onRecordingStarted() {
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timerJob?.cancel()
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timerJob = viewModelScope.launch {
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var seconds = 0L
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while (isActive) {
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_recordingState.value = RecordingState.Recording(seconds)
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delay(1000)
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seconds++
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}
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}
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}
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fun onRecordingStopped() {
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timerJob?.cancel()
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timerJob = null
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_recordingState.value = RecordingState.Idle
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}
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fun postError(message: String) {
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_errorEvents.tryEmit(message)
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// A failed start/stop shouldn't leave the UI stuck showing a
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// recording indicator that no longer reflects reality.
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if (_recordingState.value != RecordingState.Idle) {
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onRecordingStopped()
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}
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}
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override fun onCleared() {
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super.onCleared()
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timerJob?.cancel()
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}
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}
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