Avoid swallowing errors during export preparation

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

@@ -134,8 +134,15 @@ class MainActivity : ComponentActivity() {
                 val onExportClick = if (launchMode == LaunchMode.EXTERNAL_SCAN_TO_PDF) {
                     {
                         lifecycleScope.launch {
-                            val result = exportViewModel.generatePdfForExternalCall()
-                            sendActivityResult(result)
+                            try {
+                                val result = exportViewModel.generatePdfForExternalCall()
+                                sendActivityResult(result)
+                            } catch (e: Exception) {
+                                val message = "Export failed"
+                                showToast(message)
+                                appContainer.logger.e("MainActivity", message, e)
+                                return@launch
+                            }
                             viewModel.startNewDocument()
                             finish()
                         }
@@ -229,6 +236,10 @@ class MainActivity : ComponentActivity() {
         }
     }
 
+    private fun showToast(text: String) {
+        Toast.makeText(this, text, Toast.LENGTH_SHORT).show()
+    }
+
     @Composable
     private fun SettingsScreenWrapper(
         settingsViewModel: SettingsViewModel,
@@ -246,8 +257,7 @@ class MainActivity : ComponentActivity() {
                     settingsViewModel.setExportDirUri(uri.toString())
                 } catch (e: Exception) {
                     logger.e("Settings", "Failed to set export dir to $uri", e)
-                    val text = getString(R.string.error_file_picker_result)
-                    Toast.makeText(this, text, Toast.LENGTH_SHORT).show()
+                    showToast(this.getString(R.string.error_file_picker_result))
                 }
             }
         }
@@ -263,7 +273,7 @@ class MainActivity : ComponentActivity() {
                 } catch (e: Exception) {
                     val message = getString(R.string.error_file_picker_launch)
                     logger.e("Settings", message, e)
-                    Toast.makeText(this, message, Toast.LENGTH_SHORT).show()
+                    showToast(message)
                 }
             },
             onResetExportDirClick = { settingsViewModel.setExportDirUri(null) },
@@ -288,7 +298,7 @@ class MainActivity : ComponentActivity() {
                         clipboard.setClipEntry(
                             ClipData.newPlainText("FairScan logs", event.logs).toClipEntry()
                         )
-                        Toast.makeText(context, msgCopiedLogs, Toast.LENGTH_SHORT).show()
+                        showToast(msgCopiedLogs)
                     }
                     is AboutEvent.PrepareEmailWithLastImage -> {
                         val file = imageRepository.lastAddedSourceFile()
@@ -312,8 +322,7 @@ class MainActivity : ComponentActivity() {
             if (isGranted) {
                 exportViewModel.onSaveClicked()
             } else {
-                val message = getString(R.string.storage_permission_denied)
-                Toast.makeText(context, message, Toast.LENGTH_SHORT).show()
+                showToast(this.getString(R.string.storage_permission_denied))
             }
         }
         LaunchedEffect(Unit) {
@@ -423,7 +432,7 @@ class MainActivity : ComponentActivity() {
         try {
             startActivity(chooser)
         } catch (_: ActivityNotFoundException) {
-            Toast.makeText(this, getString(R.string.error_no_app), Toast.LENGTH_SHORT).show()
+            showToast(getString(R.string.error_no_app))
         }
     }
 

app/src/main/java/org/fairscan/app/domain/ExportPreparation.kt

@@ -15,6 +15,7 @@
 package org.fairscan.app.domain
 
 import org.fairscan.app.data.ImageRepository
+import org.fairscan.imageprocessing.encodeJpeg
 import org.fairscan.imageprocessing.extractDocument
 import org.fairscan.imageprocessing.resizeForMaxPixels
 import org.fairscan.imageprocessing.scaledTo
@@ -29,85 +30,84 @@ suspend fun jpegsForExport(
 
     val pages = imageRepository.pages().asSequence()
     return when (exportQuality) {
-        ExportQuality.BALANCED -> pages.mapNotNull { imageRepository.jpegBytes(it.key()) }
+        ExportQuality.BALANCED -> pages.map { jpegBytes(it, imageRepository) }
 
-        ExportQuality.LOW -> pages.mapNotNull { page ->
-            imageRepository.jpegBytes(page.key())?.let { jpeg ->
-                resizeJpegBytesForMaxPixels(
-                    jpegBytes = jpeg,
-                    maxPixels = exportQuality.maxPixels.toDouble(),
-                    jpegQuality = exportQuality.jpegQuality
-                )
-            }
+        ExportQuality.LOW -> pages.map { page ->
+            resizeJpegBytesForMaxPixels(
+                jpegBytes = jpegBytes(page, imageRepository),
+                maxPixels = exportQuality.maxPixels.toDouble(),
+                jpegQuality = exportQuality.jpegQuality
+            )
         }
 
-        ExportQuality.HIGH -> pages.mapNotNull { page ->
+        ExportQuality.HIGH -> pages.map { page ->
             val sourceJpegBytes = imageRepository.sourceJpegBytes(page.id)
             val pageMetadata = page.metadata
             val manualRotation = page.manualRotation
             if (sourceJpegBytes != null && pageMetadata != null)
                 prepareJpegForHigh(sourceJpegBytes, pageMetadata, manualRotation, exportQuality)
             else
-                imageRepository.jpegBytes(page.key())
+                jpegBytes(page, imageRepository)
         }
     }
 }
 
-fun resizeJpegBytesForMaxPixels(
+private fun jpegBytes(page: ScanPage, imageRepository: ImageRepository): ByteArray {
+    val key = page.key()
+    return imageRepository.jpegBytes(key)
+        ?: throw IllegalArgumentException("JPEG not found for $key")
+}
+
+private fun resizeJpegBytesForMaxPixels(
     jpegBytes: ByteArray,
     maxPixels: Double,
     jpegQuality: Int
-): ByteArray? {
-    val decoded = decodeJpeg(jpegBytes)
-    if (decoded == null)
-        return null
-
-    val resized = resizeForMaxPixels(decoded, maxPixels)
-    val outJpegBytes = encodeJpeg(resized, jpegQuality)
-
-    decoded.release()
-    resized.release()
-    return outJpegBytes
+): ByteArray {
+    var decoded: Mat? = null
+    var resized: Mat? = null
+    try {
+        decoded = decodeJpeg(jpegBytes)
+        resized = resizeForMaxPixels(decoded, maxPixels)
+        return encodeJpeg(resized, jpegQuality)
+    } finally {
+        decoded?.release()
+        resized?.release()
+    }
 }
 
-fun prepareJpegForHigh(
+private fun prepareJpegForHigh(
     sourceJpegBytes: ByteArray,
     pageMetadata: PageMetadata,
     manualRotation: Rotation,
     exportQuality: ExportQuality,
-): ByteArray? {
+): ByteArray {
 
-    val decoded = decodeJpeg(sourceJpegBytes)
-    if (decoded == null)
-        return null
-
-    val quad = pageMetadata.normalizedQuad.scaledTo(1,1,decoded.width(), decoded.height())
-    val page = extractDocument(
-        decoded,
-        quad,
-        pageMetadata.baseRotation.add(manualRotation).degrees,
-        pageMetadata.isColored,
-        exportQuality.maxPixels)
-    val outJpegBytes = encodeJpeg(page, exportQuality.jpegQuality)
-
-    decoded.release()
-    page.release()
-    return outJpegBytes
+    var decoded: Mat? = null
+    var page: Mat? = null
+    try {
+        decoded = decodeJpeg(sourceJpegBytes)
+        val quad = pageMetadata.normalizedQuad.scaledTo(1, 1, decoded.width(), decoded.height())
+        page = extractDocument(
+            decoded,
+            quad,
+            pageMetadata.baseRotation.add(manualRotation).degrees,
+            pageMetadata.isColored,
+            exportQuality.maxPixels
+        )
+        return encodeJpeg(page, exportQuality.jpegQuality)
+    } finally {
+        decoded?.release()
+        page?.release()
+    }
 }
 
-fun decodeJpeg(jpegBytes: ByteArray): Mat? {
+private fun decodeJpeg(jpegBytes: ByteArray): Mat {
     val src = MatOfByte(*jpegBytes)
     val decoded = Imgcodecs.imdecode(src, Imgcodecs.IMREAD_COLOR)
     src.release()
     if (decoded.empty()) {
         decoded.release()
-        return null
+        throw IllegalStateException("Failed to decode JPEG")
     }
     return decoded
 }
-
-fun encodeJpeg(mat: Mat, jpegQuality: Int): ByteArray? {
-    return runCatching {
-        org.fairscan.imageprocessing.encodeJpeg(mat, jpegQuality)
-    }.getOrNull()
-}

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

@@ -276,7 +276,7 @@ class ExportViewModel(container: AppContainer, val imageRepository: ImageReposit
     }
 
     private suspend fun save(context: Context, saveDir: SaveDir?, exportFormat: ExportFormat) {
-        val result = applyRenaming() ?: return
+        val result = applyRenaming()
         val savedItems = mutableListOf<SavedItem>()
         val filesForMediaScan = mutableListOf<File>()