android: Implement play time tacking

Co-Authored-By: Reg Tiangha <rtiangha@users.noreply.github.com>

src/android/app/src/main/java/org/citra/citra_emu/activities/EmulationActivity.kt

@@ -45,6 +45,9 @@ import org.citra.citra_emu.utils.EmulationLifecycleUtil
 import org.citra.citra_emu.utils.EmulationMenuSettings
 import org.citra.citra_emu.utils.ThemeUtil
 import org.citra.citra_emu.viewmodel.EmulationViewModel
+import androidx.core.os.BundleCompat
+import org.citra.citra_emu.utils.PlayTimeTracker
+import org.citra.citra_emu.model.Game
 
 class EmulationActivity : AppCompatActivity() {
     private val preferences: SharedPreferences
@@ -66,6 +69,8 @@ class EmulationActivity : AppCompatActivity() {
 
     private var isEmulationRunning: Boolean = false
 
+    private var emulationStartTime: Long = 0
+
     override fun onCreate(savedInstanceState: Bundle?) {
         ThemeUtil.setTheme(this)
 
@@ -105,6 +110,8 @@ class EmulationActivity : AppCompatActivity() {
         isEmulationRunning = true
         instance = this
 
+        emulationStartTime = System.currentTimeMillis()
+
         applyOrientationSettings() // Check for orientation settings at startup
     }
 
@@ -139,6 +146,17 @@ class EmulationActivity : AppCompatActivity() {
 
     override fun onDestroy() {
         EmulationLifecycleUtil.clear()
+        val sessionTime = System.currentTimeMillis() - emulationStartTime
+
+        val game = try {
+            intent.extras?.let { extras ->
+                BundleCompat.getParcelable(extras, "game", Game::class.java)
+            } ?: throw IllegalStateException("Missing game data in intent extras")
+        } catch (e: Exception) {
+            throw IllegalStateException("Failed to retrieve game data: ${e.message}", e)
+        }
+
+        PlayTimeTracker.addPlayTime(game, sessionTime)
         isEmulationRunning = false
         instance = null
         super.onDestroy()

src/android/app/src/main/java/org/citra/citra_emu/adapters/GameAdapter.kt

@@ -47,6 +47,7 @@ import org.citra.citra_emu.features.settings.utils.SettingsFile
 import org.citra.citra_emu.model.Game
 import org.citra.citra_emu.utils.GameIconUtils
 import org.citra.citra_emu.viewmodel.GamesViewModel
+import org.citra.citra_emu.utils.PlayTimeTracker
 
 class GameAdapter(private val activity: AppCompatActivity, private val inflater: LayoutInflater) :
     ListAdapter<Game, GameViewHolder>(AsyncDifferConfig.Builder(DiffCallback()).build()),
@@ -221,6 +222,12 @@ class GameAdapter(private val activity: AppCompatActivity, private val inflater:
             view.findNavController().navigate(action)
         }
 
+        bottomSheetView.findViewById<TextView>(R.id.about_game_playtime).text =
+            buildString {
+                append("Playtime: ")
+                append(PlayTimeTracker.getPlayTime(game.titleId))
+            }
+
         bottomSheetView.findViewById<MaterialButton>(R.id.game_shortcut).setOnClickListener {
             val shortcutManager = activity.getSystemService(ShortcutManager::class.java)
 

src/android/app/src/main/java/org/citra/citra_emu/utils/PlayTimeTracker.kt

@@ -0,0 +1,102 @@
+// Copyright 2025 Mandarine Project
+// Licensed under GPLv2 or any later version
+// Refer to the license.txt file included.
+
+package org.citra.citra_emu.utils
+
+import androidx.documentfile.provider.DocumentFile
+import org.citra.citra_emu.model.Game
+import org.citra.citra_emu.CitraApplication
+import kotlinx.serialization.Serializable
+import kotlinx.serialization.encodeToString
+import kotlinx.serialization.json.Json
+import java.io.BufferedReader
+import java.io.InputStreamReader
+
+@Serializable
+data class PlayTimeData(
+    val titleId: Long,
+    val title: String,
+    var totalPlayTimeMs: Long = 0
+)
+
+object PlayTimeTracker {
+    private const val PLAYTIME_FILENAME = "playtime.json"
+    private val playTimes = mutableMapOf<Long, PlayTimeData>()
+
+    init {
+        loadPlayTimes()
+    }
+
+    fun addPlayTime(game: Game, sessionTimeMs: Long) {
+        val data = playTimes.getOrPut(game.titleId) {
+            PlayTimeData(game.titleId, game.title)
+        }
+        data.totalPlayTimeMs += sessionTimeMs
+        savePlayTimes()
+    }
+
+    fun getPlayTime(titleId: Long): String {
+        // Reload playtime in case of manual file editing
+        loadPlayTimes()
+
+        val totalSeconds = (playTimes[titleId]?.totalPlayTimeMs ?: 0) / 1000
+        val hours = totalSeconds / 3600
+        val minutes = (totalSeconds % 3600) / 60
+        val seconds = totalSeconds % 60
+
+        return when {
+            hours > 0 -> "${hours}h ${minutes}m ${seconds}s"
+            minutes > 0 -> "${minutes}m ${seconds}s"
+            else -> "${seconds}s"
+        }
+    }
+
+    private fun loadPlayTimes() {
+        try {
+            val root = DocumentFile.fromTreeUri(CitraApplication.appContext, PermissionsHandler.citraDirectory)
+            val logDir = root?.findFile("log") ?: return
+            val playTimeFile = logDir.findFile(PLAYTIME_FILENAME) ?: return
+
+            val context = CitraApplication.appContext
+            val inputStream = context.contentResolver.openInputStream(playTimeFile.uri) ?: return
+            val reader = BufferedReader(InputStreamReader(inputStream))
+            val jsonString = reader.readText()
+
+            val loadedData = Json.decodeFromString<List<PlayTimeData>>(jsonString)
+            playTimes.clear()
+            loadedData.forEach { playTimes[it.titleId] = it }
+
+            reader.close()
+        } catch (e: Exception) {
+            Log.error("Failed to load play times: ${e.message}")
+        }
+    }
+
+    private fun savePlayTimes() {
+        try {
+            val root = DocumentFile.fromTreeUri(CitraApplication.appContext, PermissionsHandler.citraDirectory)
+            val logDir = root?.findFile("log")
+                ?: root?.createDirectory("log")
+                ?: return
+
+            var playTimeFile = logDir.findFile(PLAYTIME_FILENAME)
+            if (playTimeFile == null) {
+                playTimeFile = logDir.createFile("application/json", PLAYTIME_FILENAME) ?: return
+            }
+
+            val jsonString = Json.encodeToString(playTimes.values.toList())
+            val outputStream = CitraApplication.appContext.contentResolver.openOutputStream(playTimeFile.uri) ?: return
+            outputStream.write(jsonString.toByteArray())
+            outputStream.close()
+        } catch (e: Exception) {
+            Log.error("Failed to save play times: ${e.message}")
+        }
+    }
+
+    // Will be used on a later PR
+    fun deletePlayTime(titleId: Long) {
+        playTimes.remove(titleId)
+        savePlayTimes()
+    }
+}

src/android/app/src/main/res/layout/dialog_about_game.xml

@@ -44,8 +44,8 @@
                 android:layout_width="wrap_content"
                 android:layout_height="wrap_content"
                 android:textAlignment="viewStart"
-                android:textSize="20sp"
-                app:layout_constraintStart_toStartOf="parent"
+                android:textSize="15sp"
+                android:textStyle="bold"                app:layout_constraintStart_toStartOf="parent"
                 app:layout_constraintTop_toTopOf="parent"
                 tools:text="Application Title" />
 
@@ -85,6 +85,15 @@
                 app:layout_constraintTop_toBottomOf="@+id/about_game_id"
                 tools:text="Application Filename" />
 
+            <TextView
+                android:id="@+id/about_game_playtime"
+                style="?attr/textAppearanceBodyMedium"
+                android:layout_width="wrap_content"
+                android:layout_height="wrap_content"
+                app:layout_constraintStart_toStartOf="@id/about_game_title"
+                app:layout_constraintTop_toBottomOf="@+id/about_game_filename"
+                tools:text="Game Playtime" />
+
         </androidx.constraintlayout.widget.ConstraintLayout>
 
         <LinearLayout