New feature: flashlight (#61)

app/src/main/java/org/fairscan/app/view/CameraPreview.kt

@@ -18,6 +18,7 @@ import android.graphics.Bitmap
 import android.util.Log
 import android.view.ViewGroup.LayoutParams.MATCH_PARENT
 import android.widget.LinearLayout
+import androidx.camera.core.CameraControl
 import androidx.camera.core.CameraSelector
 import androidx.camera.core.ImageAnalysis
 import androidx.camera.core.ImageCapture
@@ -136,7 +137,9 @@ fun bindCameraUseCases(
     captureController.imageCapture = imageCapture
 
     val cameraProvider = cameraProviderFuture.get()
-    cameraProvider.bindToLifecycle(lifecycleOwner, cameraSelector, imageAnalysis, preview, imageCapture)
+    val camera = cameraProvider.bindToLifecycle(lifecycleOwner, cameraSelector,
+        imageAnalysis, preview, imageCapture)
+    captureController.cameraControl = camera.cameraControl
 }
 
 @Composable
@@ -197,6 +200,7 @@ fun replaceColor(bitmap: Bitmap, toReplace: Color, replacement: Color): Bitmap {
 fun Point.toOffset() = Offset(x.toFloat(), y.toFloat())
 
 class CameraCaptureController {
+    var cameraControl: CameraControl? = null
     var imageCapture: ImageCapture? = null
     private val executor = Executors.newSingleThreadExecutor()
 

app/src/main/java/org/fairscan/app/view/CameraScreen.kt

@@ -45,6 +45,10 @@ import androidx.compose.foundation.shape.CircleShape
 import androidx.compose.foundation.shape.RoundedCornerShape
 import androidx.compose.material.icons.Icons
 import androidx.compose.material.icons.filled.Done
+import androidx.compose.material.icons.filled.FlashOff
+import androidx.compose.material.icons.filled.FlashOn
+import androidx.compose.material3.Icon
+import androidx.compose.material3.IconButton
 import androidx.compose.material3.MaterialTheme
 import androidx.compose.material3.Surface
 import androidx.compose.material3.Text
@@ -93,7 +97,8 @@ data class CameraUiState(
     val captureState: CaptureState,
     val showDetectionError: Boolean,
     val isLandscape: Boolean,
-    val isDebugMode: Boolean
+    val isDebugMode: Boolean,
+    val isTorchEnabled: Boolean,
 )
 
 const val CAPTURED_IMAGE_DISPLAY_DURATION = 1500L
@@ -112,6 +117,7 @@ fun CameraScreen(
     val document by viewModel.documentUiModel.collectAsStateWithLifecycle()
     val thumbnailCoords = remember { mutableStateOf(Offset.Zero) }
     var isDebugMode by remember { mutableStateOf(false) }
+    var isTorchEnabled by remember { mutableStateOf(false) }
 
     BackHandler { navigation.back() }
 
@@ -168,7 +174,8 @@ fun CameraScreen(
             captureState,
             showDetectionError,
             isLandscape = isLandscape,
-            isDebugMode),
+            isDebugMode,
+            isTorchEnabled),
         onCapture = {
             previewView?.bitmap?.let {
                 Log.i("FairScan", "Pressed <Capture>")
@@ -180,6 +187,9 @@ fun CameraScreen(
         },
         onFinalizePressed = onFinalizePressed,
         onDebugModeSwitched = { isDebugMode = !isDebugMode },
+        onTorchSwitched = {
+            isTorchEnabled = !isTorchEnabled
+            captureController.cameraControl?.enableTorch(isTorchEnabled) },
         thumbnailCoords = thumbnailCoords,
         navigation = navigation
     )
@@ -193,6 +203,7 @@ private fun CameraScreenScaffold(
     onCapture: () -> Unit,
     onFinalizePressed: () -> Unit,
     onDebugModeSwitched: () -> Unit,
+    onTorchSwitched: () -> Unit,
     thumbnailCoords: MutableState<Offset>,
     navigation: Navigation,
 ) {
@@ -225,6 +236,7 @@ private fun CameraScreenScaffold(
                     cameraPreview,
                     cameraUiState,
                     onCapture,
+                    onTorchSwitched,
                     modifier.clickable(onClick = onPageCountClick))
         }
         if (cameraUiState.captureState is CaptureState.CapturePreview) {
@@ -238,6 +250,7 @@ private fun CameraPreviewBox(
     cameraPreview: @Composable (() -> Unit),
     cameraUiState: CameraUiState,
     onCapture: () -> Unit,
+    onTorchSwitched: () -> Unit,
     modifier: Modifier,
 ) {
     Box(
@@ -257,6 +270,20 @@ private fun CameraPreviewBox(
                 .align(Alignment.BottomCenter)
                 .padding(16.dp)
         )
+        IconButton(
+            onClick = onTorchSwitched,
+            modifier = Modifier.align(Alignment.BottomStart)
+        ) {
+            val torchEnabled = cameraUiState.isTorchEnabled
+            val icon = if (torchEnabled) Icons.Default.FlashOn else Icons.Default.FlashOff
+            Icon(
+                imageVector = icon,
+                contentDescription =
+                    stringResource(
+                        if (torchEnabled) R.string.turn_off_torch else R.string.turn_on_torch),
+                tint = Color.White
+            )
+        }
     }
 }
 
@@ -479,10 +506,11 @@ private fun ScreenPreview(captureState: CaptureState, rotationDegrees: Float = 0
                     listState = LazyListState(),
                 ),
             cameraUiState = CameraUiState(pageCount = 4, LiveAnalysisState(), captureState,
-                false, rotationDegrees > 0, false),
+                false, rotationDegrees > 0, false, false),
             onCapture = {},
             onFinalizePressed = {},
             onDebugModeSwitched = {},
+            onTorchSwitched = {},
             thumbnailCoords = thumbnailCoords,
             navigation = dummyNavigation()
         )

app/src/main/res/values-cs/strings.xml

@@ -40,6 +40,8 @@
     <string name="share">Sdílet</string>
     <string name="share_pdf">Sdílet PDF</string>
     <string name="storage_permission_denied">Nelze uložit PDF: přístup zakázán</string>
+    <string name="turn_off_torch">Vypnout svítilnu</string>
+    <string name="turn_on_torch">Zapnout svítilnu</string>
     <string name="unknown_size">Neznámá velikost</string>
     <string name="version">Verze</string>
     <string name="view_the_full_license">Zobrazit úplnou licenci</string>

app/src/main/res/values-de/strings.xml

@@ -39,6 +39,8 @@
     <string name="share">Teilen</string>
     <string name="share_pdf">PDF teilen</string>
     <string name="storage_permission_denied">PDF-Datei kann nicht gespeichert werden: Berechtigung verweigert</string>
+    <string name="turn_off_torch">Taschenlampe ausschalten</string>
+    <string name="turn_on_torch">Taschenlampe einschalten</string>
     <string name="unknown_size">Unbekannte Größe</string>
     <string name="version">Version</string>
     <string name="view_the_full_license">Vollständige Lizenz anzeigen</string>

app/src/main/res/values-es/strings.xml

@@ -39,6 +39,8 @@
     <string name="share">Compartir</string>
     <string name="share_pdf">Compartir PDF</string>
     <string name="storage_permission_denied">No se puede guardar el archivo PDF: permiso denegado</string>
+    <string name="turn_off_torch">Apagar linterna</string>
+    <string name="turn_on_torch">Encender linterna</string>
     <string name="unknown_size">Tamaño desconocido</string>
     <string name="version">Versión</string>
     <string name="view_the_full_license">Ver la licencia completa</string>

app/src/main/res/values-fr/strings.xml

@@ -39,6 +39,8 @@
     <string name="share">Partager</string>
     <string name="share_pdf">Partager le PDF</string>
     <string name="storage_permission_denied">Impossible d’enregistrer le fichier PDF : permission refusée</string>
+    <string name="turn_off_torch">Éteindre la torche</string>
+    <string name="turn_on_torch">Allumer la torche</string>
     <string name="unknown_size">Taille inconnue</string>
     <string name="version">Version</string>
     <string name="view_the_full_license">Voir la licence complète</string>

app/src/main/res/values-it/strings.xml

@@ -39,6 +39,8 @@
     <string name="share">Condividi</string>
     <string name="share_pdf">Condividi PDF</string>
     <string name="storage_permission_denied">Impossibile salvare il file PDF: autorizzazione negata</string>
+    <string name="turn_off_torch">Spegni la torcia</string>
+    <string name="turn_on_torch">Accendi la torcia</string>
     <string name="unknown_size">Dimensione sconosciuta</string>
     <string name="version">Versione</string>
     <string name="view_the_full_license">Vedi la licenza completa</string>

app/src/main/res/values-pt-rBR/strings.xml

@@ -39,6 +39,8 @@
     <string name="share">Compartilhar</string>
     <string name="share_pdf">Compartilhar PDF</string>
     <string name="storage_permission_denied">Não foi possível salvar o arquivo PDF: permissão negada</string>
+    <string name="turn_off_torch">Desligar lanterna</string>
+    <string name="turn_on_torch">Ligar lanterna</string>
     <string name="unknown_size">Tamanho desconhecido</string>
     <string name="version">Versão</string>
     <string name="view_the_full_license">Ver licença completa</string>

app/src/main/res/values-ru/strings.xml

@@ -39,6 +39,8 @@
     <string name="share">Поделиться</string>
     <string name="share_pdf">Поделиться PDF</string>
     <string name="storage_permission_denied">Не удается сохранить файл PDF: в разрешении отказано</string>
+    <string name="turn_off_torch">Выключить фонарик</string>
+    <string name="turn_on_torch">Включить фонарик</string>
     <string name="unknown_size">Неизвестный размер</string>
     <string name="version">Версия</string>
     <string name="view_the_full_license">Просмотреть полную лицензию</string>

app/src/main/res/values-zh/strings.xml

@@ -39,6 +39,8 @@
     <string name="share">共享</string>
     <string name="share_pdf">共享 PDF</string>
     <string name="storage_permission_denied">无法保存PDF文件：权限被拒绝</string>
+    <string name="turn_off_torch">关闭手电筒</string>
+    <string name="turn_on_torch">打开手电筒</string>
     <string name="unknown_size">未知大小</string>
     <string name="version">版本</string>
     <string name="view_the_full_license">查看完整许可证</string>

app/src/main/res/values/strings.xml

@@ -40,6 +40,8 @@
     <string name="share">Share</string>
     <string name="share_pdf">Share PDF</string>
     <string name="storage_permission_denied">Cannot save PDF file: permission was denied</string>
+    <string name="turn_off_torch">Turn off torch</string>
+    <string name="turn_on_torch">Turn on torch</string>
     <string name="unknown_size">Unknown size</string>
     <string name="version">Version</string>
     <string name="view_the_full_license">View the full license</string>