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feat: preserve operation state across screen rotation #73

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111e261
feat: preserve operation state across screen rotation
Copilot Apr 6, 2026
a90b0d4
fix: use safe default for pendingUserBirthYear restore, shorten chang…
Copilot Apr 6, 2026
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170 changes: 165 additions & 5 deletions app/src/main/java/net/duhowpi/nfccoins/MainActivity.kt
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Original file line number Diff line number Diff line change
Expand Up @@ -87,6 +87,37 @@ class MainActivity : AppCompatActivity() {
private const val LOG_TAG = "MainActivity"
/** Maximum age of a transaction (in seconds) for it to be eligible for undo. */
private const val UNDO_MAX_AGE_SECONDS = 24L * 60 * 60

// Keys used in onSaveInstanceState / onRestoreInstanceState
private const val KEY_PENDING_ACTION = "pendingAction"
private const val KEY_SELECTED_BUTTON_INDEX = "selectedButtonIndex"
private const val KEY_CURRENT_BALANCE = "currentBalance"
private const val KEY_PENDING_ADD_AMOUNT = "pendingAddAmount"
private const val KEY_CUSTOM_DEDUCT_AMOUNT = "customDeductAmount"
private const val KEY_IS_CUSTOM_AMOUNT_MODE = "isCustomAmountMode"
private const val KEY_IS_ADD_BALANCE_MODE = "isAddBalanceMode"
private const val KEY_PENDING_WRITE_UID = "pendingWriteUid"
private const val KEY_PENDING_WRITE_BALANCE = "pendingWriteBalance"
private const val KEY_PENDING_WRITE_TX = "pendingWriteTx"
private const val KEY_REPLAY_CANDIDATE_UID = "replayCandidateUid"
private const val KEY_REPLAY_CANDIDATE_CHECKSUM = "replayCandidateChecksum"
private const val KEY_REPLAY_CONFIRMED_UID = "replayConfirmedUid"
private const val KEY_REPLAY_CONFIRMED_CHECKSUM = "replayConfirmedChecksum"
private const val KEY_PENDING_SINGLE_RECHARGE = "pendingSingleRecharge"
private const val KEY_PENDING_USER_BIRTH_YEAR = "pendingUserBirthYear"
private const val KEY_BATTERY_OPT_REQUESTED = "batteryOptRequested"
private const val KEY_TV_STATUS = "tvStatus"
private const val KEY_TV_CARD_ID = "tvCardId"
private const val KEY_TV_BALANCE_BEFORE = "tvBalanceBefore"
private const val KEY_TV_BALANCE_AFTER = "tvBalanceAfter"
private const val KEY_TV_ACTUAL_BALANCE = "tvActualBalance"
private const val KEY_VIS_BEFORE_AFTER = "visBeforeAfter"
private const val KEY_VIS_ACTUAL_BALANCE = "visActualBalance"
private const val KEY_VIS_MINOR_ICON = "visMinorIcon"
private const val KEY_VIS_TX_HISTORY = "visTxHistory"
private const val KEY_TV_TX_PREFIX = "tvTx_"
private const val KEY_VIS_TX_PREFIX = "visTx_"
private const val KEY_VIS_REPLAY_ALLOW = "visReplayAllow"
}

private enum class PendingAction { NONE, WITHDRAW_BALANCE, ADD_BALANCE, FORMAT_CARD, RESET_CARD, UNDO_TRANSACTION }
Expand Down Expand Up @@ -139,6 +170,8 @@ class MainActivity : AppCompatActivity() {

private var wakeLock: PowerManager.WakeLock? = null
private var batteryOptimizationRequested = false
/** Holds the bundle passed to [onRestoreInstanceState] until it can be consumed at the end of [onResume]. */
private var savedStateToRestore: Bundle? = null
private val nfcOperationExecutor: ExecutorService = Executors.newSingleThreadExecutor { runnable ->
Thread(runnable, "nfc-op-timeout").apply { isDaemon = true }
}
Expand Down Expand Up @@ -185,10 +218,12 @@ class MainActivity : AppCompatActivity() {
return
}

if (intent?.action == NfcAdapter.ACTION_TECH_DISCOVERED) {
handleNfcIntent(intent)
} else if (intent?.action == Intent.ACTION_VIEW) {
handleAmountIntent(intent)
if (savedInstanceState == null) {
if (intent?.action == NfcAdapter.ACTION_TECH_DISCOVERED) {
handleNfcIntent(intent)
} else if (intent?.action == Intent.ACTION_VIEW) {
handleAmountIntent(intent)
}
}

// Pre-warm the audio hardware so the first startTone() call fires without the
Expand Down Expand Up @@ -271,6 +306,10 @@ class MainActivity : AppCompatActivity() {
applyThemeColor()
rebuildCustomButtons()
invalidateOptionsMenu()
// Restore operation state after a configuration change (e.g. rotation). This must run
// after checkNfcEnabled() and rebuildCustomButtons() so they don't overwrite our state.
savedStateToRestore?.let { restoreOperationState(it) }
savedStateToRestore = null
}

override fun onPause() {
Expand All @@ -279,7 +318,9 @@ class MainActivity : AppCompatActivity() {
releaseWakeLock()
// Deselect any active button and reset UI state when leaving so that returning from
// another activity (history, settings, …) never leaves the interface in a stale mode.
if (selectedButtonIndex >= 0 || isAddBalanceMode) {
// Skip this reset during configuration changes (e.g. rotation) so the operation state
// is preserved and can be restored in the new Activity instance.
if (!isChangingConfigurations && (selectedButtonIndex >= 0 || isAddBalanceMode)) {
handler.removeCallbacks(autoResetRunnable)
resetToWaiting()
}
Expand All @@ -289,6 +330,12 @@ class MainActivity : AppCompatActivity() {
super.onDestroy()
releaseWakeLock()
handler.removeCallbacksAndMessages(BEEP_TOKEN)
if (isChangingConfigurations) {
// Clean up any pending UI runnables so they don't fire on stale views.
handler.removeCallbacks(autoResetRunnable)
handler.removeCallbacks(buttonModeIdleRunnable)
handler.removeCallbacksAndMessages(FLASH_TOKEN)
}
if (isFinishing) {
synchronized(toneGeneratorLock) {
sharedToneGenerator?.release()
Expand All @@ -307,6 +354,119 @@ class MainActivity : AppCompatActivity() {
}
}

override fun onSaveInstanceState(outState: Bundle) {
super.onSaveInstanceState(outState)
outState.putInt(KEY_PENDING_ACTION, pendingAction.ordinal)
outState.putInt(KEY_SELECTED_BUTTON_INDEX, selectedButtonIndex)
outState.putInt(KEY_CURRENT_BALANCE, currentBalance)
outState.putInt(KEY_PENDING_ADD_AMOUNT, pendingAddAmount)
outState.putInt(KEY_CUSTOM_DEDUCT_AMOUNT, customDeductAmount)
outState.putBoolean(KEY_IS_CUSTOM_AMOUNT_MODE, isCustomAmountMode)
outState.putBoolean(KEY_IS_ADD_BALANCE_MODE, isAddBalanceMode)
outState.putBoolean(KEY_PENDING_SINGLE_RECHARGE, pendingSingleRecharge)
outState.putInt(KEY_PENDING_USER_BIRTH_YEAR, pendingUserBirthYear)
outState.putBoolean(KEY_BATTERY_OPT_REQUESTED, batteryOptimizationRequested)
pendingWrite?.let {
outState.putByteArray(KEY_PENDING_WRITE_UID, it.uid)
outState.putByteArray(KEY_PENDING_WRITE_BALANCE, it.balanceData)
outState.putByteArray(KEY_PENDING_WRITE_TX, it.transactions)
}
replayAllowanceCandidate?.let {
outState.putString(KEY_REPLAY_CANDIDATE_UID, it.cardUid)
outState.putString(KEY_REPLAY_CANDIDATE_CHECKSUM, it.checksum)
}
replayAllowanceConfirmed?.let {
outState.putString(KEY_REPLAY_CONFIRMED_UID, it.cardUid)
outState.putString(KEY_REPLAY_CONFIRMED_CHECKSUM, it.checksum)
}
// Save display state for views that Android does not auto-persist
outState.putString(KEY_TV_STATUS, tvStatus.text.toString())
outState.putString(KEY_TV_CARD_ID, tvCardId.text.toString())
outState.putInt(KEY_VIS_BEFORE_AFTER, layoutBeforeAfter.visibility)
outState.putString(KEY_TV_BALANCE_BEFORE, tvBalanceBefore.text.toString())
outState.putString(KEY_TV_BALANCE_AFTER, tvBalanceAfter.text.toString())
outState.putInt(KEY_VIS_ACTUAL_BALANCE, tvActualBalance.visibility)
outState.putString(KEY_TV_ACTUAL_BALANCE, tvActualBalance.text.toString())
outState.putInt(KEY_VIS_MINOR_ICON, tvMinorIcon.visibility)
outState.putInt(KEY_VIS_TX_HISTORY, layoutTransactionHistory.visibility)
tvTx.forEachIndexed { i, tv ->
outState.putString("$KEY_TV_TX_PREFIX$i", tv.text.toString())
outState.putInt("$KEY_VIS_TX_PREFIX$i", tv.visibility)
}
outState.putInt(KEY_VIS_REPLAY_ALLOW, tvReplayAllow.visibility)
}

override fun onRestoreInstanceState(savedInstanceState: Bundle) {
super.onRestoreInstanceState(savedInstanceState)
// Defer the full restore until the end of onResume, after checkNfcEnabled() and
// rebuildCustomButtons() have run, so they don't overwrite our restored state.
savedStateToRestore = savedInstanceState
}

/**
* Restores operation state and display after a configuration change (e.g. screen rotation).
* Called at the end of [onResume] so it runs after [checkNfcEnabled] and [rebuildCustomButtons].
*/
private fun restoreOperationState(b: Bundle) {
// Restore logical state
pendingAction = PendingAction.values()[b.getInt(KEY_PENDING_ACTION, PendingAction.NONE.ordinal)]
selectedButtonIndex = b.getInt(KEY_SELECTED_BUTTON_INDEX, -1)
currentBalance = b.getInt(KEY_CURRENT_BALANCE, -1)
pendingAddAmount = b.getInt(KEY_PENDING_ADD_AMOUNT, 0)
customDeductAmount = b.getInt(KEY_CUSTOM_DEDUCT_AMOUNT, 0)
isCustomAmountMode = b.getBoolean(KEY_IS_CUSTOM_AMOUNT_MODE, false)
isAddBalanceMode = b.getBoolean(KEY_IS_ADD_BALANCE_MODE, false)
pendingSingleRecharge = b.getBoolean(KEY_PENDING_SINGLE_RECHARGE, false)
pendingUserBirthYear = b.getInt(KEY_PENDING_USER_BIRTH_YEAR, MifareClassicHelper.toUserBirthYear(MifareClassicHelper.DEFAULT_USER_BYTE))
batteryOptimizationRequested = b.getBoolean(KEY_BATTERY_OPT_REQUESTED, false)
val uid = b.getByteArray(KEY_PENDING_WRITE_UID)
val balanceData = b.getByteArray(KEY_PENDING_WRITE_BALANCE)
val txData = b.getByteArray(KEY_PENDING_WRITE_TX)
pendingWrite = if (uid != null && balanceData != null && txData != null)
BaseCoinCard.PendingWriteData(uid, balanceData, txData) else null
val candidateUid = b.getString(KEY_REPLAY_CANDIDATE_UID)
val candidateChecksum = b.getString(KEY_REPLAY_CANDIDATE_CHECKSUM)
replayAllowanceCandidate = if (candidateUid != null && candidateChecksum != null)
ReplayAllowance(candidateUid, candidateChecksum) else null
val confirmedUid = b.getString(KEY_REPLAY_CONFIRMED_UID)
val confirmedChecksum = b.getString(KEY_REPLAY_CONFIRMED_CHECKSUM)
replayAllowanceConfirmed = if (confirmedUid != null && confirmedChecksum != null)
ReplayAllowance(confirmedUid, confirmedChecksum) else null

// Restore display state
b.getString(KEY_TV_STATUS)?.let { tvStatus.text = it }
b.getString(KEY_TV_CARD_ID)?.let { tvCardId.text = it }
layoutBeforeAfter.visibility = b.getInt(KEY_VIS_BEFORE_AFTER, View.GONE)
if (layoutBeforeAfter.visibility == View.VISIBLE) {
tvBalanceBefore.text = b.getString(KEY_TV_BALANCE_BEFORE, "")
tvBalanceAfter.text = b.getString(KEY_TV_BALANCE_AFTER, "")
}
tvActualBalance.visibility = b.getInt(KEY_VIS_ACTUAL_BALANCE, View.GONE)
if (tvActualBalance.visibility == View.VISIBLE) {
tvActualBalance.text = b.getString(KEY_TV_ACTUAL_BALANCE, "")
}
tvMinorIcon.visibility = b.getInt(KEY_VIS_MINOR_ICON, View.GONE)
layoutTransactionHistory.visibility = b.getInt(KEY_VIS_TX_HISTORY, View.GONE)
tvTx.forEachIndexed { i, tv ->
tv.text = b.getString("$KEY_TV_TX_PREFIX$i", "")
tv.visibility = b.getInt("$KEY_VIS_TX_PREFIX$i", View.GONE)
}
tvReplayAllow.visibility = b.getInt(KEY_VIS_REPLAY_ALLOW, View.GONE)

// Re-apply button selection styling on the freshly-built button views
if (selectedButtonIndex >= 0) {
applyButtonSelectionStyle(selectedButtonIndex, selected = true)
}

// Re-schedule auto-reset for actions that use it
when (pendingAction) {
PendingAction.FORMAT_CARD, PendingAction.RESET_CARD -> scheduleAutoReset()
else -> {}
}

invalidateOptionsMenu()
}

// -------------------------------------------------------------------------
// Keep-screen-on helpers
// -------------------------------------------------------------------------
Expand Down
2 changes: 1 addition & 1 deletion fastlane/metadata/android/en-US/changelogs/15.txt
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@@ -1 +1 @@
Add user-facing changes for the next release here.
- Fixed screen rotation resetting active operation