Split MainViewModel: extract ExportViewModel

app/src/main/AndroidManifest.xml

@@ -15,6 +15,7 @@
         android:fullBackupContent="@xml/backup_rules"
         android:icon="@mipmap/ic_launcher"
         android:label="@string/app_name"
+        android:name=".FairScanApp"
         android:roundIcon="@mipmap/ic_launcher_round"
         android:supportsRtl="true"
         android:theme="@style/Theme.FairScan"

app/src/main/java/org/fairscan/app/FairScanApp.kt

@@ -0,0 +1,46 @@
+/*
+ * Copyright 2025 Pierre-Yves Nicolas
+ *
+ * This program is free software: you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the Free
+ * Software Foundation, either version 3 of the License, or (at your option)
+ * any later version.
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
+ * more details.
+ * You should have received a copy of the GNU General Public License along with
+ * this program. If not, see <https://www.gnu.org/licenses/>.
+ */
+package org.fairscan.app
+
+import android.app.Application
+import android.content.Context
+import android.os.Environment
+import org.fairscan.app.data.ImageRepository
+import org.fairscan.app.data.PdfFileManager
+import org.fairscan.app.platform.AndroidPdfWriter
+import org.fairscan.app.platform.OpenCvTransformations
+import java.io.File
+
+class FairScanApp : Application() {
+    lateinit var appContainer: AppContainer
+
+    override fun onCreate() {
+        super.onCreate()
+        appContainer = AppContainer(this)
+    }
+}
+
+const val THUMBNAIL_SIZE_DP = 120
+
+class AppContainer(context: Context) {
+    private val density = context.resources.displayMetrics.density
+    private val thumbnailSizePx = (THUMBNAIL_SIZE_DP * density).toInt()
+    val imageRepository = ImageRepository(context.filesDir, OpenCvTransformations(), thumbnailSizePx)
+    val pdfFileManager = PdfFileManager(
+        File(context.cacheDir, "pdfs"),
+        Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DOWNLOADS),
+        AndroidPdfWriter()
+    )
+}

app/src/main/java/org/fairscan/app/MainActivity.kt

@@ -51,15 +51,17 @@ import org.fairscan.app.data.GeneratedPdf
 import org.fairscan.app.ui.Navigation
 import org.fairscan.app.ui.Screen
 import org.fairscan.app.ui.components.rememberCameraPermissionState
-import org.fairscan.app.ui.theme.FairScanTheme
 import org.fairscan.app.ui.screens.AboutScreen
-import org.fairscan.app.ui.screens.camera.CameraScreen
 import org.fairscan.app.ui.screens.DocumentScreen
-import org.fairscan.app.ui.screens.ExportScreenWrapper
 import org.fairscan.app.ui.screens.HomeScreen
 import org.fairscan.app.ui.screens.LibrariesScreen
 import org.fairscan.app.ui.screens.camera.CameraEvent
+import org.fairscan.app.ui.screens.camera.CameraScreen
 import org.fairscan.app.ui.screens.camera.CameraViewModel
+import org.fairscan.app.ui.screens.export.ExportScreenWrapper
+import org.fairscan.app.ui.screens.export.ExportViewModel
+import org.fairscan.app.ui.screens.export.PdfGenerationActions
+import org.fairscan.app.ui.theme.FairScanTheme
 import org.opencv.android.OpenCVLoader
 
 private const val PDF_MIME_TYPE = "application/pdf"
@@ -70,10 +72,11 @@ class MainActivity : ComponentActivity() {
         super.onCreate(savedInstanceState)
         initLibraries()
         val viewModel: MainViewModel by viewModels { MainViewModel.getFactory(this) }
-        lifecycleScope.launch(Dispatchers.IO) {
-            viewModel.cleanUpOldPdfs(1000 * 3600)
-        }
         val cameraViewModel: CameraViewModel by viewModels { CameraViewModel.getFactory(this) }
+        val exportViewModel: ExportViewModel by viewModels { ExportViewModel.getFactory(this) }
+        lifecycleScope.launch(Dispatchers.IO) {
+            exportViewModel.cleanUpOldPdfs(1000 * 3600)
+        }
         enableEdgeToEdge()
         setContent {
             LaunchedEffect(Unit) {
@@ -88,7 +91,7 @@ class MainActivity : ComponentActivity() {
             val liveAnalysisState by cameraViewModel.liveAnalysisState.collectAsStateWithLifecycle()
             val document by viewModel.documentUiModel.collectAsStateWithLifecycle()
             val cameraPermission = rememberCameraPermissionState()
-            val savePdf = { savePdf(viewModel.getFinalPdf(), viewModel) }
+            val savePdf = { savePdf(exportViewModel.getFinalPdf(), viewModel, exportViewModel) }
             val storagePermissionLauncher = rememberLauncherForActivityResult(
                 ActivityResultContracts.RequestPermission()
             ) { isGranted ->
@@ -146,12 +149,12 @@ class MainActivity : ComponentActivity() {
                         ExportScreenWrapper(
                             navigation = navigation,
                             pdfActions = PdfGenerationActions(
-                                startGeneration = viewModel::startPdfGeneration,
+                                startGeneration = exportViewModel::startPdfGeneration,
-                                setFilename = viewModel::setFilename,
+                                setFilename = exportViewModel::setFilename,
-                                uiStateFlow = viewModel.pdfUiState,
+                                uiStateFlow = exportViewModel.pdfUiState,
-                                sharePdf = { sharePdf(viewModel.getFinalPdf(), viewModel) },
+                                sharePdf = { sharePdf(exportViewModel.getFinalPdf(), exportViewModel) },
                                 savePdf = { checkPermissionThen(storagePermissionLauncher, savePdf) },
-                                openPdf = { openPdf(viewModel.pdfUiState.value.savedFileUri) }
+                                openPdf = { openPdf(exportViewModel.pdfUiState.value.savedFileUri) }
                             ),
                             onCloseScan = {
                                 viewModel.startNewDocument()
@@ -170,7 +173,7 @@ class MainActivity : ComponentActivity() {
         }
     }
 
-    private fun sharePdf(generatedPdf: GeneratedPdf?, viewModel: MainViewModel) {
+    private fun sharePdf(generatedPdf: GeneratedPdf?, viewModel: ExportViewModel) {
         if (generatedPdf == null)
             return
         viewModel.setPdfAsShared()
@@ -205,14 +208,18 @@ class MainActivity : ComponentActivity() {
         }
     }
 
-    private fun savePdf(generatedPdf: GeneratedPdf?, viewModel: MainViewModel) {
+    private fun savePdf(
+        generatedPdf: GeneratedPdf?,
+        viewModel: MainViewModel,
+        exportViewModel: ExportViewModel
+    ) {
         if (generatedPdf == null)
             return
         val appScope = CoroutineScope(Dispatchers.IO)
         val context = this
         appScope.launch {
             try {
-                val targetFile = viewModel.saveFile(generatedPdf.file)
+                val targetFile = exportViewModel.saveFile(generatedPdf.file)
                 viewModel.addRecentDocument(targetFile.absolutePath, generatedPdf.pageCount)
 
                 suspendCancellableCoroutine { continuation ->

app/src/main/java/org/fairscan/app/MainViewModel.kt

@@ -17,44 +17,29 @@ package org.fairscan.app
 import android.content.Context
 import android.graphics.Bitmap
 import android.graphics.BitmapFactory
-import android.os.Environment
-import android.util.Log
-import androidx.core.net.toUri
 import androidx.datastore.core.DataStore
 import androidx.lifecycle.ViewModel
 import androidx.lifecycle.ViewModelProvider
 import androidx.lifecycle.viewModelScope
 import androidx.lifecycle.viewmodel.CreationExtras
 import kotlinx.collections.immutable.persistentListOf
-import kotlinx.coroutines.Dispatchers
-import kotlinx.coroutines.Job
 import kotlinx.coroutines.flow.MutableStateFlow
 import kotlinx.coroutines.flow.SharingStarted
 import kotlinx.coroutines.flow.StateFlow
-import kotlinx.coroutines.flow.asStateFlow
 import kotlinx.coroutines.flow.map
 import kotlinx.coroutines.flow.stateIn
 import kotlinx.coroutines.flow.update
 import kotlinx.coroutines.launch
-import kotlinx.coroutines.withContext
-import org.fairscan.app.data.GeneratedPdf
 import org.fairscan.app.data.ImageRepository
-import org.fairscan.app.data.PdfFileManager
 import org.fairscan.app.data.recentDocumentsDataStore
-import org.fairscan.app.platform.AndroidPdfWriter
-import org.fairscan.app.platform.OpenCvTransformations
 import org.fairscan.app.ui.NavigationState
 import org.fairscan.app.ui.Screen
 import org.fairscan.app.ui.state.DocumentUiModel
-import org.fairscan.app.ui.state.PdfGenerationUiState
 import org.fairscan.app.ui.state.RecentDocumentUiState
 import java.io.File
 
-const val THUMBNAIL_SIZE_DP = 120
-
 class MainViewModel(
     private val imageRepository: ImageRepository,
-    private val pdfFileManager: PdfFileManager,
     private val recentDocumentsDataStore: DataStore<RecentDocuments>,
 ): ViewModel() {
 
@@ -62,15 +47,9 @@ class MainViewModel(
         fun getFactory(context: Context) = object : ViewModelProvider.Factory {
             @Suppress("UNCHECKED_CAST")
             override fun <T : ViewModel> create(modelClass: Class<T>, extras: CreationExtras): T {
-                val density = context.resources.displayMetrics.density
+                val app = context.applicationContext as FairScanApp
-                val thumbnailSizePx = (THUMBNAIL_SIZE_DP * density).toInt()
                 return MainViewModel(
-                    ImageRepository(context.filesDir, OpenCvTransformations(), thumbnailSizePx),
+                    app.appContainer.imageRepository,
-                    PdfFileManager(
-                        File(context.cacheDir, "pdfs"),
-                        Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DOWNLOADS),
-                        AndroidPdfWriter()
-                    ),
                     context.recentDocumentsDataStore,
                 ) as T
             }
@@ -137,85 +116,6 @@ class MainViewModel(
         return bytes?.let { BitmapFactory.decodeByteArray(it, 0, it.size) }
     }
 
-    private suspend fun generatePdf(): GeneratedPdf = withContext(Dispatchers.IO) {
-        val imageIds = imageRepository.imageIds()
-        val jpegs = imageIds.asSequence()
-            .map { id -> imageRepository.getContent(id) }
-            .filterNotNull()
-        return@withContext pdfFileManager.generatePdf(jpegs)
-    }
-
-    private val _pdfUiState = MutableStateFlow(PdfGenerationUiState())
-    val pdfUiState: StateFlow<PdfGenerationUiState> = _pdfUiState.asStateFlow()
-
-    private var generationJob: Job? = null
-    private var desiredFilename: String = ""
-
-    fun setFilename(name: String) {
-        desiredFilename = name
-    }
-
-    fun startPdfGeneration() {
-        cancelPdfGeneration()
-        generationJob = viewModelScope.launch {
-            try {
-                val result = generatePdf()
-                _pdfUiState.update {
-                    it.copy(
-                        isGenerating = false,
-                        generatedPdf = result
-                    )
-                }
-            } catch (e: Exception) {
-                Log.e("FairScan", "PDF generation failed", e)
-                _pdfUiState.update {
-                    it.copy(
-                        isGenerating = false,
-                        errorMessage = "PDF generation failed"
-                    )
-                }
-            }
-        }
-    }
-
-    fun cancelPdfGeneration() {
-        generationJob?.cancel()
-        _pdfUiState.value = PdfGenerationUiState()
-    }
-
-    fun setPdfAsShared() {
-        _pdfUiState.update { it.copy(hasSharedPdf = true) }
-    }
-
-    fun getFinalPdf(): GeneratedPdf? {
-        val tempPdf = _pdfUiState.value.generatedPdf ?: return null
-        val tempFile = tempPdf.file
-        val fileName = PdfFileManager.addExtensionIfMissing(desiredFilename)
-        val newFile = File(tempFile.parentFile, fileName)
-        if (tempFile.absolutePath != newFile.absolutePath) {
-            if (newFile.exists()) newFile.delete()
-            val success = tempFile.renameTo(newFile)
-            if (!success) return null
-            _pdfUiState.update {
-                it.copy(generatedPdf = GeneratedPdf(
-                    newFile, tempPdf.sizeInBytes, tempPdf.pageCount)
-                )
-            }
-        }
-        return _pdfUiState.value.generatedPdf
-    }
-
-    fun saveFile(pdfFile: File): File {
-        val copiedFile = pdfFileManager.copyToExternalDir(pdfFile)
-        _pdfUiState.update { it.copy(savedFileUri = copiedFile.toUri()) }
-        return copiedFile
-    }
-
-    fun cleanUpOldPdfs(thresholdInMillis: Int) {
-        pdfFileManager.cleanUpOldFiles(thresholdInMillis)
-    }
-
-
     val recentDocuments: StateFlow<List<RecentDocumentUiState>> =
         recentDocumentsDataStore.data.map {
             it.documentsList.map {
@@ -256,13 +156,3 @@ class MainViewModel(
         _pageIds.value = imageRepository.imageIds()
     }
 }
-
-// TODO Move somewhere else: ViewModel should not depend on that
-data class PdfGenerationActions(
-    val startGeneration: () -> Unit,
-    val setFilename: (String) -> Unit,
-    val uiStateFlow: StateFlow<PdfGenerationUiState>,// TODO is it ok to have that here?
-    val sharePdf: () -> Unit,
-    val savePdf: () -> Unit,
-    val openPdf: () -> Unit,
-)

app/src/main/java/org/fairscan/app/ui/screens/export/ExportScreen.kt

@@ -12,7 +12,7 @@
  * You should have received a copy of the GNU General Public License along with
  * this program. If not, see <https://www.gnu.org/licenses/>.
  */
-package org.fairscan.app.ui.screens
+package org.fairscan.app.ui.screens.export
 
 import android.content.Context
 import android.text.format.Formatter
@@ -66,11 +66,9 @@ import androidx.compose.ui.text.font.FontStyle
 import androidx.compose.ui.tooling.preview.Preview
 import androidx.compose.ui.unit.dp
 import androidx.core.net.toUri
+import org.fairscan.app.R
 import org.fairscan.app.data.GeneratedPdf
 import org.fairscan.app.ui.Navigation
-import org.fairscan.app.PdfGenerationActions
-import org.fairscan.app.R
-import org.fairscan.app.ui.state.PdfGenerationUiState
 import org.fairscan.app.ui.components.AboutScreenNavButton
 import org.fairscan.app.ui.components.BackButton
 import org.fairscan.app.ui.components.MainActionButton
@@ -78,6 +76,7 @@ import org.fairscan.app.ui.components.NewDocumentDialog
 import org.fairscan.app.ui.components.isLandscape
 import org.fairscan.app.ui.components.pageCountText
 import org.fairscan.app.ui.dummyNavigation
+import org.fairscan.app.ui.state.PdfGenerationUiState
 import org.fairscan.app.ui.theme.FairScanTheme
 import java.io.File
 import java.text.SimpleDateFormat

app/src/main/java/org/fairscan/app/ui/screens/export/ExportViewModel.kt

@@ -0,0 +1,143 @@
+/*
+ * Copyright 2025 Pierre-Yves Nicolas
+ *
+ * This program is free software: you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the Free
+ * Software Foundation, either version 3 of the License, or (at your option)
+ * any later version.
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
+ * more details.
+ * You should have received a copy of the GNU General Public License along with
+ * this program. If not, see <https://www.gnu.org/licenses/>.
+ */
+package org.fairscan.app.ui.screens.export
+
+import android.content.Context
+import android.util.Log
+import androidx.core.net.toUri
+import androidx.lifecycle.ViewModel
+import androidx.lifecycle.ViewModelProvider
+import androidx.lifecycle.viewModelScope
+import androidx.lifecycle.viewmodel.CreationExtras
+import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.Job
+import kotlinx.coroutines.flow.MutableStateFlow
+import kotlinx.coroutines.flow.StateFlow
+import kotlinx.coroutines.flow.asStateFlow
+import kotlinx.coroutines.flow.update
+import kotlinx.coroutines.launch
+import kotlinx.coroutines.withContext
+import org.fairscan.app.FairScanApp
+import org.fairscan.app.data.GeneratedPdf
+import org.fairscan.app.data.ImageRepository
+import org.fairscan.app.data.PdfFileManager
+import org.fairscan.app.ui.state.PdfGenerationUiState
+import java.io.File
+
+class ExportViewModel(
+    private val pdfFileManager: PdfFileManager,
+    private val imageRepository: ImageRepository,
+): ViewModel() {
+
+    companion object {
+        fun getFactory(context: Context) = object : ViewModelProvider.Factory {
+            @Suppress("UNCHECKED_CAST")
+            override fun <T : ViewModel> create(modelClass: Class<T>, extras: CreationExtras): T {
+                val app = context.applicationContext as FairScanApp
+                val pdfFileManager = app.appContainer.pdfFileManager
+                val imageRepository = app.appContainer.imageRepository
+                return ExportViewModel(pdfFileManager, imageRepository) as T
+            }
+        }
+    }
+
+    private suspend fun generatePdf(): GeneratedPdf = withContext(Dispatchers.IO) {
+        val imageIds = imageRepository.imageIds()
+        val jpegs = imageIds.asSequence()
+            .map { id -> imageRepository.getContent(id) }
+            .filterNotNull()
+        return@withContext pdfFileManager.generatePdf(jpegs)
+    }
+
+    private val _pdfUiState = MutableStateFlow(PdfGenerationUiState())
+    val pdfUiState: StateFlow<PdfGenerationUiState> = _pdfUiState.asStateFlow()
+
+    private var generationJob: Job? = null
+    private var desiredFilename: String = ""
+
+    fun setFilename(name: String) {
+        desiredFilename = name
+    }
+
+    fun startPdfGeneration() {
+        cancelPdfGeneration()
+        generationJob = viewModelScope.launch {
+            try {
+                val result = generatePdf()
+                _pdfUiState.update {
+                    it.copy(
+                        isGenerating = false,
+                        generatedPdf = result
+                    )
+                }
+            } catch (e: Exception) {
+                Log.e("FairScan", "PDF generation failed", e)
+                _pdfUiState.update {
+                    it.copy(
+                        isGenerating = false,
+                        errorMessage = "PDF generation failed"
+                    )
+                }
+            }
+        }
+    }
+
+    fun cancelPdfGeneration() {
+        generationJob?.cancel()
+        _pdfUiState.value = PdfGenerationUiState()
+    }
+
+    fun setPdfAsShared() {
+        _pdfUiState.update { it.copy(hasSharedPdf = true) }
+    }
+
+    fun getFinalPdf(): GeneratedPdf? {
+        val tempPdf = _pdfUiState.value.generatedPdf ?: return null
+        val tempFile = tempPdf.file
+        val fileName = PdfFileManager.addExtensionIfMissing(desiredFilename)
+        val newFile = File(tempFile.parentFile, fileName)
+        if (tempFile.absolutePath != newFile.absolutePath) {
+            if (newFile.exists()) newFile.delete()
+            val success = tempFile.renameTo(newFile)
+            if (!success) return null
+            _pdfUiState.update {
+                it.copy(generatedPdf = GeneratedPdf(
+                    newFile, tempPdf.sizeInBytes, tempPdf.pageCount)
+                )
+            }
+        }
+        return _pdfUiState.value.generatedPdf
+    }
+
+    fun saveFile(pdfFile: File): File {
+        val copiedFile = pdfFileManager.copyToExternalDir(pdfFile)
+        _pdfUiState.update { it.copy(savedFileUri = copiedFile.toUri()) }
+        return copiedFile
+    }
+
+    fun cleanUpOldPdfs(thresholdInMillis: Int) {
+        pdfFileManager.cleanUpOldFiles(thresholdInMillis)
+    }
+
+}
+
+data class PdfGenerationActions(
+    val startGeneration: () -> Unit,
+    val setFilename: (String) -> Unit,
+    val uiStateFlow: StateFlow<PdfGenerationUiState>,// TODO is it ok to have that here?
+    val sharePdf: () -> Unit,
+    val savePdf: () -> Unit,
+    val openPdf: () -> Unit,
+)