Add interactive gallery preview before applying tilt-shift effect

Instead of immediately processing gallery images, show a preview where
users can adjust blur parameters before committing. Adds Cancel/Apply
buttons and hides camera-only controls during gallery preview mode.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

README.md

@@ -18,7 +18,7 @@ A dedicated Android camera app for tilt-shift photography with real-time preview
 
 ## Requirements
 
-- Android 8.0 (API 26) or higher
+- Android 15 (API 35) or higher
 - Device with camera
 - OpenGL ES 2.0 support
 
@@ -66,8 +66,7 @@ app/src/main/java/no/naiv/tiltshift/
 │   ├── ZoomControl.kt        # Zoom UI component
 │   └── LensSwitcher.kt       # Lens selection UI
 ├── storage/
-│   ├── PhotoSaver.kt         # MediaStore integration
+│   └── PhotoSaver.kt         # MediaStore integration & EXIF handling
-│   └── ExifWriter.kt         # EXIF metadata handling
 └── util/
     ├── OrientationDetector.kt
     ├── LocationProvider.kt

app/src/main/java/no/naiv/tiltshift/camera/CameraManager.kt

@@ -2,6 +2,7 @@ package no.naiv.tiltshift.camera
 
 import android.content.Context
 import android.graphics.SurfaceTexture
+import android.util.Log
 import android.util.Size
 import android.view.Surface
 import androidx.camera.core.Camera
@@ -24,6 +25,10 @@ import java.util.concurrent.Executor
  */
 class CameraManager(private val context: Context) {
 
+    companion object {
+        private const val TAG = "CameraManager"
+    }
+
     private var cameraProvider: ProcessCameraProvider? = null
     private var camera: Camera? = null
     private var preview: Preview? = null
@@ -32,6 +37,13 @@ class CameraManager(private val context: Context) {
 
     val lensController = LensController()
 
+    private val _error = MutableStateFlow<String?>(null)
+    val error: StateFlow<String?> = _error.asStateFlow()
+
+    fun clearError() {
+        _error.value = null
+    }
+
     private val _zoomRatio = MutableStateFlow(1.0f)
     val zoomRatio: StateFlow<Float> = _zoomRatio.asStateFlow()
 
@@ -82,10 +94,11 @@ class CameraManager(private val context: Context) {
             .setResolutionSelector(resolutionSelector)
             .build()
 
-        // Image capture use case for high-res photos
+        // Image capture use case
-        imageCapture = ImageCapture.Builder()
+        val captureBuilder = ImageCapture.Builder()
             .setCaptureMode(ImageCapture.CAPTURE_MODE_MAXIMIZE_QUALITY)
-            .build()
+
+        imageCapture = captureBuilder.build()
 
         // Select camera based on front/back preference
         val cameraSelector = if (_isFrontCamera.value) {
@@ -117,8 +130,8 @@ class CameraManager(private val context: Context) {
             }
 
         } catch (e: Exception) {
-            // Camera binding failed
+            Log.e(TAG, "Camera binding failed", e)
-            e.printStackTrace()
+            _error.value = "Camera failed: ${e.message}"
         }
     }
 

app/src/main/java/no/naiv/tiltshift/camera/ImageCaptureHandler.kt

@@ -5,11 +5,15 @@ import android.graphics.Bitmap
 import android.graphics.BitmapFactory
 import android.graphics.Matrix
 import android.location.Location
+import android.net.Uri
+import android.util.Log
 import androidx.camera.core.ImageCapture
 import androidx.camera.core.ImageCaptureException
 import androidx.camera.core.ImageProxy
 import androidx.exifinterface.media.ExifInterface
+import kotlinx.coroutines.Dispatchers
 import kotlinx.coroutines.suspendCancellableCoroutine
+import kotlinx.coroutines.withContext
 import no.naiv.tiltshift.effect.BlurMode
 import no.naiv.tiltshift.effect.BlurParameters
 import no.naiv.tiltshift.storage.PhotoSaver
@@ -28,12 +32,19 @@ class ImageCaptureHandler(
     private val photoSaver: PhotoSaver
 ) {
 
+    companion object {
+        private const val TAG = "ImageCaptureHandler"
+    }
+
     /**
      * Holds the processed bitmap ready for saving, produced inside the
      * camera callback (synchronous CPU work) and consumed afterwards
      * in the caller's coroutine context.
      */
-    private class ProcessedCapture(val bitmap: Bitmap)
+    private class ProcessedCapture(
+        val originalBitmap: Bitmap,
+        val processedBitmap: Bitmap
+    )
 
     /**
      * Captures a photo and applies the tilt-shift effect.
@@ -58,26 +69,31 @@ class ImageCaptureHandler(
                 executor,
                 object : ImageCapture.OnImageCapturedCallback() {
                     override fun onCaptureSuccess(imageProxy: ImageProxy) {
+                        var currentBitmap: Bitmap? = null
                         try {
                             val imageRotation = imageProxy.imageInfo.rotationDegrees
 
-                            var bitmap = imageProxyToBitmap(imageProxy)
+                            currentBitmap = imageProxyToBitmap(imageProxy)
                             imageProxy.close()
 
-                            if (bitmap == null) {
+                            if (currentBitmap == null) {
                                 continuation.resume(
                                     SaveResult.Error("Failed to convert image") as Any
                                 )
                                 return
                             }
 
-                            bitmap = rotateBitmap(bitmap, imageRotation, isFrontCamera)
+                            currentBitmap = rotateBitmap(currentBitmap, imageRotation, isFrontCamera)
 
-                            val processedBitmap = applyTiltShiftEffect(bitmap, blurParams)
+                            val processedBitmap = applyTiltShiftEffect(currentBitmap, blurParams)
-                            bitmap.recycle()
+                            // Keep originalBitmap alive — both are recycled after saving
+                            val original = currentBitmap
+                            currentBitmap = null
 
-                            continuation.resume(ProcessedCapture(processedBitmap))
+                            continuation.resume(ProcessedCapture(original, processedBitmap))
                         } catch (e: Exception) {
+                            Log.e(TAG, "Image processing failed", e)
+                            currentBitmap?.recycle()
                             continuation.resume(
                                 SaveResult.Error("Capture failed: ${e.message}", e) as Any
                             )
@@ -95,22 +111,46 @@ class ImageCaptureHandler(
             )
         }
 
-        // Phase 2: save to disk in the caller's coroutine context (suspend-safe)
+        // Phase 2: save both original and processed to disk (suspend-safe)
         if (captureResult is ProcessedCapture) {
             return try {
-                photoSaver.saveBitmap(
+                val thumbnail = createThumbnail(captureResult.processedBitmap)
-                    captureResult.bitmap,
+                val result = photoSaver.saveBitmapPair(
-                    ExifInterface.ORIENTATION_NORMAL,
+                    original = captureResult.originalBitmap,
-                    location
+                    processed = captureResult.processedBitmap,
+                    orientation = ExifInterface.ORIENTATION_NORMAL,
+                    location = location
                 )
+                if (result is SaveResult.Success) {
+                    result.copy(thumbnail = thumbnail)
+                } else {
+                    thumbnail?.recycle()
+                    result
+                }
             } finally {
-                captureResult.bitmap.recycle()
+                captureResult.originalBitmap.recycle()
+                captureResult.processedBitmap.recycle()
             }
         }
 
         return captureResult as SaveResult
     }
 
+    /**
+     * Creates a small thumbnail copy of a bitmap for in-app preview.
+     */
+    private fun createThumbnail(source: Bitmap, maxSize: Int = 160): Bitmap? {
+        return try {
+            val scale = maxSize.toFloat() / maxOf(source.width, source.height)
+            val width = (source.width * scale).toInt()
+            val height = (source.height * scale).toInt()
+            Bitmap.createScaledBitmap(source, width, height, true)
+        } catch (e: Exception) {
+            Log.w(TAG, "Failed to create thumbnail", e)
+            null
+        }
+    }
+
     /**
      * Rotates a bitmap to the correct orientation.
      */
@@ -149,35 +189,157 @@ class ImageCaptureHandler(
         return BitmapFactory.decodeByteArray(bytes, 0, bytes.size)
     }
 
+    /**
+     * Loads a gallery image and applies EXIF rotation, returning the bitmap for preview.
+     * The caller owns the returned bitmap and is responsible for recycling it.
+     */
+    suspend fun loadGalleryImage(imageUri: Uri): Bitmap? = withContext(Dispatchers.IO) {
+        try {
+            val bitmap = loadBitmapFromUri(imageUri)
+                ?: return@withContext null
+            applyExifRotation(imageUri, bitmap)
+        } catch (e: Exception) {
+            Log.e(TAG, "Failed to load gallery image for preview", e)
+            null
+        }
+    }
+
+    /**
+     * Processes an existing image from the gallery through the tilt-shift pipeline.
+     * Loads the image, applies EXIF rotation, processes the effect, and saves both versions.
+     */
+    suspend fun processExistingImage(
+        imageUri: Uri,
+        blurParams: BlurParameters,
+        location: Location?
+    ): SaveResult = withContext(Dispatchers.IO) {
+        var originalBitmap: Bitmap? = null
+        var processedBitmap: Bitmap? = null
+        try {
+            originalBitmap = loadBitmapFromUri(imageUri)
+                ?: return@withContext SaveResult.Error("Failed to load image")
+
+            originalBitmap = applyExifRotation(imageUri, originalBitmap)
+
+            processedBitmap = applyTiltShiftEffect(originalBitmap, blurParams)
+
+            val thumbnail = createThumbnail(processedBitmap)
+
+            val result = photoSaver.saveBitmapPair(
+                original = originalBitmap,
+                processed = processedBitmap,
+                orientation = ExifInterface.ORIENTATION_NORMAL,
+                location = location
+            )
+
+            if (result is SaveResult.Success) {
+                result.copy(thumbnail = thumbnail)
+            } else {
+                thumbnail?.recycle()
+                result
+            }
+        } catch (e: Exception) {
+            Log.e(TAG, "Gallery image processing failed", e)
+            SaveResult.Error("Processing failed: ${e.message}", e)
+        } finally {
+            originalBitmap?.recycle()
+            processedBitmap?.recycle()
+        }
+    }
+
+    /**
+     * Loads a bitmap from a content URI.
+     */
+    private fun loadBitmapFromUri(uri: Uri): Bitmap? {
+        return try {
+            context.contentResolver.openInputStream(uri)?.use { stream ->
+                BitmapFactory.decodeStream(stream)
+            }
+        } catch (e: Exception) {
+            Log.e(TAG, "Failed to load bitmap from URI", e)
+            null
+        }
+    }
+
+    /**
+     * Reads EXIF orientation from a content URI and applies the
+     * required rotation/flip to the bitmap.
+     */
+    private fun applyExifRotation(uri: Uri, bitmap: Bitmap): Bitmap {
+        val orientation = try {
+            context.contentResolver.openInputStream(uri)?.use { stream ->
+                ExifInterface(stream).getAttributeInt(
+                    ExifInterface.TAG_ORIENTATION,
+                    ExifInterface.ORIENTATION_NORMAL
+                )
+            } ?: ExifInterface.ORIENTATION_NORMAL
+        } catch (e: Exception) {
+            Log.w(TAG, "Failed to read EXIF orientation", e)
+            ExifInterface.ORIENTATION_NORMAL
+        }
+
+        val matrix = Matrix()
+        when (orientation) {
+            ExifInterface.ORIENTATION_ROTATE_90 -> matrix.postRotate(90f)
+            ExifInterface.ORIENTATION_ROTATE_180 -> matrix.postRotate(180f)
+            ExifInterface.ORIENTATION_ROTATE_270 -> matrix.postRotate(270f)
+            ExifInterface.ORIENTATION_FLIP_HORIZONTAL -> matrix.postScale(-1f, 1f)
+            ExifInterface.ORIENTATION_FLIP_VERTICAL -> matrix.postScale(1f, -1f)
+            ExifInterface.ORIENTATION_TRANSPOSE -> {
+                matrix.postRotate(90f)
+                matrix.postScale(-1f, 1f)
+            }
+            ExifInterface.ORIENTATION_TRANSVERSE -> {
+                matrix.postRotate(270f)
+                matrix.postScale(-1f, 1f)
+            }
+            else -> return bitmap
+        }
+
+        val rotated = Bitmap.createBitmap(
+            bitmap, 0, 0, bitmap.width, bitmap.height, matrix, true
+        )
+        if (rotated != bitmap) {
+            bitmap.recycle()
+        }
+        return rotated
+    }
+
     /**
      * Applies tilt-shift blur effect to a bitmap.
      * Supports both linear and radial modes.
+     *
+     * All intermediate bitmaps are tracked and recycled in a finally block
+     * so that an OOM or other exception does not leak native memory.
      */
     private fun applyTiltShiftEffect(source: Bitmap, params: BlurParameters): Bitmap {
         val width = source.width
         val height = source.height
 
-        // Create output bitmap
+        var result: Bitmap? = null
-        val result = Bitmap.createBitmap(width, height, Bitmap.Config.ARGB_8888)
+        var scaled: Bitmap? = null
+        var blurred: Bitmap? = null
+        var blurredFullSize: Bitmap? = null
+        var mask: Bitmap? = null
 
-        // For performance, we use a scaled-down version for blur and composite
+        try {
-        val scaleFactor = 4 // Blur a 1/4 size image for speed
+            result = Bitmap.createBitmap(width, height, Bitmap.Config.ARGB_8888)
+
+            val scaleFactor = 4
             val blurredWidth = width / scaleFactor
             val blurredHeight = height / scaleFactor
 
-        // Create scaled bitmap for blur
+            scaled = Bitmap.createScaledBitmap(source, blurredWidth, blurredHeight, true)
-        val scaled = Bitmap.createScaledBitmap(source, blurredWidth, blurredHeight, true)
 
-        // Apply stack blur (fast approximation)
+            blurred = stackBlur(scaled, (params.blurAmount * 25).toInt().coerceIn(1, 25))
-        val blurred = stackBlur(scaled, (params.blurAmount * 25).toInt().coerceIn(1, 25))
             scaled.recycle()
+            scaled = null
 
-        // Scale blurred back up
+            blurredFullSize = Bitmap.createScaledBitmap(blurred, width, height, true)
-        val blurredFullSize = Bitmap.createScaledBitmap(blurred, width, height, true)
             blurred.recycle()
+            blurred = null
 
-        // Create gradient mask based on tilt-shift parameters
+            mask = createGradientMask(width, height, params)
-        val mask = createGradientMask(width, height, params)
 
             // Composite: blend original with blurred based on mask
             val pixels = IntArray(width * height)
@@ -189,7 +351,9 @@ class ImageCaptureHandler(
             mask.getPixels(maskPixels, 0, width, 0, 0, width, height)
 
             blurredFullSize.recycle()
+            blurredFullSize = null
             mask.recycle()
+            mask = null
 
             for (i in pixels.indices) {
                 val maskAlpha = (maskPixels[i] and 0xFF) / 255f
@@ -208,7 +372,17 @@ class ImageCaptureHandler(
             }
 
             result.setPixels(pixels, 0, width, 0, 0, width, height)
-        return result
+
+            val output = result
+            result = null // prevent finally from recycling the returned bitmap
+            return output
+        } finally {
+            result?.recycle()
+            scaled?.recycle()
+            blurred?.recycle()
+            blurredFullSize?.recycle()
+            mask?.recycle()
+        }
     }
 
     /**

app/src/main/java/no/naiv/tiltshift/camera/LensController.kt

@@ -88,11 +88,4 @@ class LensController {
         return availableLenses[currentLensIndex]
     }
 
-    /**
-     * Common zoom levels that can be achieved through digital zoom.
-     * These are presented as quick-select buttons.
-     */
-    fun getZoomPresets(): List<Float> {
-        return listOf(0.5f, 1.0f, 2.0f, 5.0f)
-    }
 }

app/src/main/java/no/naiv/tiltshift/storage/ExifWriter.kt

@@ -1,96 +0,0 @@
-package no.naiv.tiltshift.storage
-
-import android.location.Location
-import androidx.exifinterface.media.ExifInterface
-import java.io.File
-import java.text.SimpleDateFormat
-import java.util.Date
-import java.util.Locale
-
-/**
- * Writes EXIF metadata to captured images.
- */
-class ExifWriter {
-
-    private val dateTimeFormat = SimpleDateFormat("yyyy:MM:dd HH:mm:ss", Locale.US)
-
-    /**
-     * Writes EXIF data to the specified image file.
-     */
-    fun writeExifData(
-        file: File,
-        orientation: Int,
-        location: Location?,
-        make: String = "Android",
-        model: String = android.os.Build.MODEL
-    ) {
-        try {
-            val exif = ExifInterface(file)
-
-            // Orientation
-            exif.setAttribute(ExifInterface.TAG_ORIENTATION, orientation.toString())
-
-            // Date/time
-            val dateTime = dateTimeFormat.format(Date())
-            exif.setAttribute(ExifInterface.TAG_DATETIME, dateTime)
-            exif.setAttribute(ExifInterface.TAG_DATETIME_ORIGINAL, dateTime)
-            exif.setAttribute(ExifInterface.TAG_DATETIME_DIGITIZED, dateTime)
-
-            // Camera info
-            exif.setAttribute(ExifInterface.TAG_MAKE, make)
-            exif.setAttribute(ExifInterface.TAG_MODEL, model)
-            exif.setAttribute(ExifInterface.TAG_SOFTWARE, "Tilt-Shift Camera")
-
-            // GPS location
-            if (location != null) {
-                setLocationExif(exif, location)
-            }
-
-            exif.saveAttributes()
-        } catch (e: Exception) {
-            e.printStackTrace()
-        }
-    }
-
-    private fun setLocationExif(exif: ExifInterface, location: Location) {
-        // Latitude
-        val latitude = location.latitude
-        val latRef = if (latitude >= 0) "N" else "S"
-        exif.setAttribute(ExifInterface.TAG_GPS_LATITUDE, convertToDMS(Math.abs(latitude)))
-        exif.setAttribute(ExifInterface.TAG_GPS_LATITUDE_REF, latRef)
-
-        // Longitude
-        val longitude = location.longitude
-        val lonRef = if (longitude >= 0) "E" else "W"
-        exif.setAttribute(ExifInterface.TAG_GPS_LONGITUDE, convertToDMS(Math.abs(longitude)))
-        exif.setAttribute(ExifInterface.TAG_GPS_LONGITUDE_REF, lonRef)
-
-        // Altitude
-        if (location.hasAltitude()) {
-            val altitude = location.altitude
-            val altRef = if (altitude >= 0) "0" else "1"
-            exif.setAttribute(ExifInterface.TAG_GPS_ALTITUDE, "${Math.abs(altitude).toLong()}/1")
-            exif.setAttribute(ExifInterface.TAG_GPS_ALTITUDE_REF, altRef)
-        }
-
-        // Timestamp
-        val gpsTimeFormat = SimpleDateFormat("HH:mm:ss", Locale.US)
-        val gpsDateFormat = SimpleDateFormat("yyyy:MM:dd", Locale.US)
-        val timestamp = Date(location.time)
-        exif.setAttribute(ExifInterface.TAG_GPS_TIMESTAMP, gpsTimeFormat.format(timestamp))
-        exif.setAttribute(ExifInterface.TAG_GPS_DATESTAMP, gpsDateFormat.format(timestamp))
-    }
-
-    /**
-     * Converts decimal degrees to DMS (degrees/minutes/seconds) format for EXIF.
-     */
-    private fun convertToDMS(coordinate: Double): String {
-        val degrees = coordinate.toInt()
-        val minutesDecimal = (coordinate - degrees) * 60
-        val minutes = minutesDecimal.toInt()
-        val seconds = (minutesDecimal - minutes) * 60
-
-        // EXIF format: "degrees/1,minutes/1,seconds/1000"
-        return "$degrees/1,$minutes/1,${(seconds * 1000).toLong()}/1000"
-    }
-}

app/src/main/java/no/naiv/tiltshift/storage/PhotoSaver.kt

@@ -3,28 +3,30 @@ package no.naiv.tiltshift.storage
 import android.content.ContentValues
 import android.content.Context
 import android.graphics.Bitmap
-import android.graphics.BitmapFactory
-import android.graphics.Canvas
-import android.graphics.Paint
 import android.location.Location
 import android.net.Uri
 import android.os.Build
 import android.os.Environment
 import android.provider.MediaStore
+import android.util.Log
 import androidx.exifinterface.media.ExifInterface
 import kotlinx.coroutines.Dispatchers
 import kotlinx.coroutines.withContext
-import java.io.File
-import java.io.FileOutputStream
 import java.text.SimpleDateFormat
 import java.util.Date
 import java.util.Locale
 
+
 /**
  * Result of a photo save operation.
  */
 sealed class SaveResult {
-    data class Success(val uri: Uri, val path: String) : SaveResult()
+    data class Success(
+        val uri: Uri,
+        val path: String,
+        val originalUri: Uri? = null,
+        val thumbnail: android.graphics.Bitmap? = null
+    ) : SaveResult()
     data class Error(val message: String, val exception: Exception? = null) : SaveResult()
 }
 
@@ -33,7 +35,9 @@ sealed class SaveResult {
  */
 class PhotoSaver(private val context: Context) {
 
-    private val exifWriter = ExifWriter()
+    companion object {
+        private const val TAG = "PhotoSaver"
+    }
 
     private val fileNameFormat = SimpleDateFormat("yyyyMMdd_HHmmss", Locale.US)
 
@@ -45,100 +49,68 @@ class PhotoSaver(private val context: Context) {
         orientation: Int,
         location: Location?
     ): SaveResult = withContext(Dispatchers.IO) {
-        try {
         val fileName = "TILTSHIFT_${fileNameFormat.format(Date())}.jpg"
-
+        saveSingleBitmap(fileName, bitmap, orientation, location)
-            // Create content values for MediaStore
-            val contentValues = ContentValues().apply {
-                put(MediaStore.Images.Media.DISPLAY_NAME, fileName)
-                put(MediaStore.Images.Media.MIME_TYPE, "image/jpeg")
-                put(MediaStore.Images.Media.DATE_ADDED, System.currentTimeMillis() / 1000)
-                put(MediaStore.Images.Media.DATE_TAKEN, System.currentTimeMillis())
-
-                if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.Q) {
-                    put(MediaStore.Images.Media.RELATIVE_PATH, "${Environment.DIRECTORY_PICTURES}/TiltShift")
-                    put(MediaStore.Images.Media.IS_PENDING, 1)
-                }
-            }
-
-            // Insert into MediaStore
-            val contentResolver = context.contentResolver
-            val uri = contentResolver.insert(
-                MediaStore.Images.Media.EXTERNAL_CONTENT_URI,
-                contentValues
-            ) ?: return@withContext SaveResult.Error("Failed to create MediaStore entry")
-
-            // Write bitmap to output stream
-            contentResolver.openOutputStream(uri)?.use { outputStream ->
-                bitmap.compress(Bitmap.CompressFormat.JPEG, 95, outputStream)
-            } ?: return@withContext SaveResult.Error("Failed to open output stream")
-
-            // Write EXIF data
-            writeExifToUri(uri, orientation, location)
-
-            // Mark as complete (API 29+)
-            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.Q) {
-                contentValues.clear()
-                contentValues.put(MediaStore.Images.Media.IS_PENDING, 0)
-                contentResolver.update(uri, contentValues, null, null)
-            }
-
-            // Get the file path for display
-            val path = getPathFromUri(uri)
-
-            SaveResult.Success(uri, path)
-        } catch (e: Exception) {
-            SaveResult.Error("Failed to save photo: ${e.message}", e)
-        }
     }
 
     /**
-     * Saves a JPEG file (from CameraX ImageCapture) to the gallery.
+     * Saves both original and processed bitmaps to the gallery.
+     * Uses a shared timestamp so paired files sort together.
+     * Returns the processed image's URI as the primary result.
      */
-    suspend fun saveJpegFile(
+    suspend fun saveBitmapPair(
-        sourceFile: File,
+        original: Bitmap,
+        processed: Bitmap,
         orientation: Int,
         location: Location?
     ): SaveResult = withContext(Dispatchers.IO) {
-        try {
+        val timestamp = fileNameFormat.format(Date())
-            val fileName = "TILTSHIFT_${fileNameFormat.format(Date())}.jpg"
+        val processedFileName = "TILTSHIFT_${timestamp}.jpg"
+        val originalFileName = "ORIGINAL_${timestamp}.jpg"
 
+        val processedResult = saveSingleBitmap(processedFileName, processed, orientation, location)
+        if (processedResult is SaveResult.Error) return@withContext processedResult
+
+        val originalResult = saveSingleBitmap(originalFileName, original, orientation, location)
+        val originalUri = (originalResult as? SaveResult.Success)?.uri
+
+        (processedResult as SaveResult.Success).copy(originalUri = originalUri)
+    }
+
+    /**
+     * Core save logic: writes a single bitmap to MediaStore with EXIF data.
+     */
+    private fun saveSingleBitmap(
+        fileName: String,
+        bitmap: Bitmap,
+        orientation: Int,
+        location: Location?
+    ): SaveResult {
+        return try {
             val contentValues = ContentValues().apply {
                 put(MediaStore.Images.Media.DISPLAY_NAME, fileName)
                 put(MediaStore.Images.Media.MIME_TYPE, "image/jpeg")
                 put(MediaStore.Images.Media.DATE_ADDED, System.currentTimeMillis() / 1000)
                 put(MediaStore.Images.Media.DATE_TAKEN, System.currentTimeMillis())
-
-                if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.Q) {
                 put(MediaStore.Images.Media.RELATIVE_PATH, "${Environment.DIRECTORY_PICTURES}/TiltShift")
                 put(MediaStore.Images.Media.IS_PENDING, 1)
             }
-            }
 
             val contentResolver = context.contentResolver
             val uri = contentResolver.insert(
                 MediaStore.Images.Media.EXTERNAL_CONTENT_URI,
                 contentValues
-            ) ?: return@withContext SaveResult.Error("Failed to create MediaStore entry")
+            ) ?: return SaveResult.Error("Failed to create MediaStore entry")
 
-            // Copy file to MediaStore
             contentResolver.openOutputStream(uri)?.use { outputStream ->
-                sourceFile.inputStream().use { inputStream ->
+                bitmap.compress(Bitmap.CompressFormat.JPEG, 95, outputStream)
-                    inputStream.copyTo(outputStream)
+            } ?: return SaveResult.Error("Failed to open output stream")
-                }
-            } ?: return@withContext SaveResult.Error("Failed to open output stream")
 
-            // Write EXIF data
             writeExifToUri(uri, orientation, location)
 
-            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.Q) {
             contentValues.clear()
             contentValues.put(MediaStore.Images.Media.IS_PENDING, 0)
             contentResolver.update(uri, contentValues, null, null)
-            }
-
-            // Clean up source file
-            sourceFile.delete()
 
             val path = getPathFromUri(uri)
             SaveResult.Success(uri, path)
@@ -169,7 +141,7 @@ class PhotoSaver(private val context: Context) {
                 exif.saveAttributes()
             }
         } catch (e: Exception) {
-            e.printStackTrace()
+            Log.w(TAG, "Failed to write EXIF data", e)
         }
     }
 

app/src/main/java/no/naiv/tiltshift/ui/CameraScreen.kt

@@ -1,15 +1,20 @@
 package no.naiv.tiltshift.ui
 
+import android.content.Intent
+import android.graphics.Bitmap
 import android.graphics.SurfaceTexture
 import android.location.Location
+import android.net.Uri
 import android.opengl.GLSurfaceView
 import android.view.Surface
 import androidx.compose.animation.AnimatedVisibility
 import androidx.compose.animation.fadeIn
 import androidx.compose.animation.fadeOut
+import androidx.compose.animation.scaleIn
 import androidx.compose.foundation.background
 import androidx.compose.foundation.border
 import androidx.compose.foundation.clickable
+import androidx.compose.foundation.systemGestureExclusion
 import androidx.compose.foundation.layout.Arrangement
 import androidx.compose.foundation.layout.Box
 import androidx.compose.foundation.layout.Column
@@ -25,10 +30,14 @@ import androidx.compose.foundation.layout.statusBarsPadding
 import androidx.compose.foundation.layout.width
 import androidx.compose.foundation.shape.CircleShape
 import androidx.compose.foundation.shape.RoundedCornerShape
+import androidx.activity.compose.rememberLauncherForActivityResult
+import androidx.activity.result.PickVisualMediaRequest
+import androidx.activity.result.contract.ActivityResultContracts
 import androidx.compose.material.icons.Icons
 import androidx.compose.material.icons.filled.Check
 import androidx.compose.material.icons.filled.Close
 import androidx.compose.material.icons.filled.FlipCameraAndroid
+import androidx.compose.material.icons.filled.PhotoLibrary
 import androidx.compose.material3.Icon
 import androidx.compose.material3.IconButton
 import androidx.compose.material3.Slider
@@ -46,8 +55,11 @@ import androidx.compose.runtime.rememberUpdatedState
 import androidx.compose.runtime.setValue
 import androidx.compose.ui.Alignment
 import androidx.compose.ui.Modifier
+import androidx.compose.foundation.Image
 import androidx.compose.ui.draw.clip
 import androidx.compose.ui.graphics.Color
+import androidx.compose.ui.graphics.asImageBitmap
+import androidx.compose.ui.layout.ContentScale
 import androidx.compose.ui.platform.LocalContext
 import androidx.lifecycle.compose.LocalLifecycleOwner
 import androidx.compose.ui.unit.dp
@@ -97,13 +109,53 @@ fun CameraScreen(
     var showSaveError by remember { mutableStateOf<String?>(null) }
     var showControls by remember { mutableStateOf(false) }
 
+    // Thumbnail state for last captured photo
+    var lastSavedUri by remember { mutableStateOf<Uri?>(null) }
+    var lastThumbnailBitmap by remember { mutableStateOf<Bitmap?>(null) }
+
+    // Gallery preview mode: non-null means we're previewing a gallery image
+    var galleryBitmap by remember { mutableStateOf<Bitmap?>(null) }
+    var galleryImageUri by remember { mutableStateOf<Uri?>(null) }
+    val isGalleryPreview = galleryBitmap != null
+
     var currentRotation by remember { mutableStateOf(Surface.ROTATION_0) }
     var currentLocation by remember { mutableStateOf<Location?>(null) }
 
+    // Gallery picker: load image for interactive preview before processing
+    val galleryLauncher = rememberLauncherForActivityResult(
+        contract = ActivityResultContracts.PickVisualMedia()
+    ) { uri ->
+        if (uri != null && !isCapturing && !isGalleryPreview) {
+            scope.launch {
+                val bitmap = captureHandler.loadGalleryImage(uri)
+                if (bitmap != null) {
+                    galleryBitmap = bitmap
+                    galleryImageUri = uri
+                } else {
+                    haptics.error()
+                    showSaveError = "Failed to load image"
+                    delay(2000)
+                    showSaveError = null
+                }
+            }
+        }
+    }
+
     val zoomRatio by cameraManager.zoomRatio.collectAsState()
     val minZoom by cameraManager.minZoomRatio.collectAsState()
     val maxZoom by cameraManager.maxZoomRatio.collectAsState()
     val isFrontCamera by cameraManager.isFrontCamera.collectAsState()
+    val cameraError by cameraManager.error.collectAsState()
+
+    // Show camera errors via the existing error UI
+    LaunchedEffect(cameraError) {
+        cameraError?.let { message ->
+            showSaveError = message
+            cameraManager.clearError()
+            delay(2000)
+            showSaveError = null
+        }
+    }
 
     // Collect orientation updates
     LaunchedEffect(Unit) {
@@ -143,6 +195,8 @@ fun CameraScreen(
         onDispose {
             cameraManager.release()
             renderer?.release()
+            lastThumbnailBitmap?.recycle()
+            galleryBitmap?.recycle()
         }
     }
 
@@ -151,6 +205,19 @@ fun CameraScreen(
             .fillMaxSize()
             .background(Color.Black)
     ) {
+        // Main view: gallery preview image or camera GL surface
+        if (isGalleryPreview) {
+            galleryBitmap?.let { bmp ->
+                Image(
+                    bitmap = bmp.asImageBitmap(),
+                    contentDescription = "Gallery preview",
+                    contentScale = ContentScale.Fit,
+                    modifier = Modifier
+                        .fillMaxSize()
+                        .background(Color.Black)
+                )
+            }
+        } else {
             // OpenGL Surface for camera preview with effect
             AndroidView(
                 factory = { ctx ->
@@ -170,6 +237,7 @@ fun CameraScreen(
                 },
                 modifier = Modifier.fillMaxSize()
             )
+        }
 
         // Tilt-shift overlay (gesture handling + visualization)
         TiltShiftOverlay(
@@ -179,8 +247,10 @@ fun CameraScreen(
                 haptics.tick()
             },
             onZoomChange = { zoomDelta ->
+                if (!isGalleryPreview) {
                     val newZoom = (zoomRatio * zoomDelta).coerceIn(minZoom, maxZoom)
                     cameraManager.setZoom(newZoom)
+                }
             },
             modifier = Modifier.fillMaxSize()
         )
@@ -197,10 +267,15 @@ fun CameraScreen(
                 horizontalArrangement = Arrangement.SpaceBetween,
                 verticalAlignment = Alignment.CenterVertically
             ) {
+                if (!isGalleryPreview) {
                     // Zoom indicator
                     ZoomIndicator(currentZoom = zoomRatio)
+                } else {
+                    Spacer(modifier = Modifier.width(1.dp))
+                }
 
                 Row(verticalAlignment = Alignment.CenterVertically) {
+                    if (!isGalleryPreview) {
                         // Camera flip button
                         IconButton(
                             onClick = {
@@ -214,6 +289,7 @@ fun CameraScreen(
                                 tint = Color.White
                             )
                         }
+                    }
 
                     // Toggle controls button
                     IconButton(
@@ -270,9 +346,89 @@ fun CameraScreen(
             modifier = Modifier
                 .align(Alignment.BottomCenter)
                 .navigationBarsPadding()
-                .padding(bottom = 24.dp),
+                .padding(bottom = 48.dp)
+                .systemGestureExclusion(),
             horizontalAlignment = Alignment.CenterHorizontally
         ) {
+            if (isGalleryPreview) {
+                // Gallery preview mode: Cancel | Apply
+                Row(
+                    verticalAlignment = Alignment.CenterVertically,
+                    horizontalArrangement = Arrangement.spacedBy(48.dp)
+                ) {
+                    // Cancel button
+                    IconButton(
+                        onClick = {
+                            galleryBitmap?.recycle()
+                            galleryBitmap = null
+                            galleryImageUri = null
+                        },
+                        modifier = Modifier
+                            .size(56.dp)
+                            .clip(CircleShape)
+                            .background(Color(0x80000000))
+                    ) {
+                        Icon(
+                            imageVector = Icons.Default.Close,
+                            contentDescription = "Cancel",
+                            tint = Color.White,
+                            modifier = Modifier.size(28.dp)
+                        )
+                    }
+
+                    // Apply button
+                    IconButton(
+                        onClick = {
+                            val uri = galleryImageUri ?: return@IconButton
+                            if (!isCapturing) {
+                                isCapturing = true
+                                haptics.heavyClick()
+                                scope.launch {
+                                    val result = captureHandler.processExistingImage(
+                                        imageUri = uri,
+                                        blurParams = blurParams,
+                                        location = currentLocation
+                                    )
+                                    when (result) {
+                                        is SaveResult.Success -> {
+                                            haptics.success()
+                                            lastThumbnailBitmap?.recycle()
+                                            lastThumbnailBitmap = result.thumbnail
+                                            lastSavedUri = result.uri
+                                            showSaveSuccess = true
+                                            delay(1500)
+                                            showSaveSuccess = false
+                                        }
+                                        is SaveResult.Error -> {
+                                            haptics.error()
+                                            showSaveError = result.message
+                                            delay(2000)
+                                            showSaveError = null
+                                        }
+                                    }
+                                    galleryBitmap?.recycle()
+                                    galleryBitmap = null
+                                    galleryImageUri = null
+                                    isCapturing = false
+                                }
+                            }
+                        },
+                        enabled = !isCapturing,
+                        modifier = Modifier
+                            .size(56.dp)
+                            .clip(CircleShape)
+                            .background(Color(0xFFFFB300))
+                    ) {
+                        Icon(
+                            imageVector = Icons.Default.Check,
+                            contentDescription = "Apply effect",
+                            tint = Color.Black,
+                            modifier = Modifier.size(28.dp)
+                        )
+                    }
+                }
+            } else {
+                // Camera mode: Zoom presets + Gallery | Capture | Spacer
                 // Zoom presets (only show for back camera)
                 if (!isFrontCamera) {
                     ZoomControl(
@@ -288,6 +444,31 @@ fun CameraScreen(
                     Spacer(modifier = Modifier.height(24.dp))
                 }
 
+                // Gallery button | Capture button | Spacer for symmetry
+                Row(
+                    verticalAlignment = Alignment.CenterVertically,
+                    horizontalArrangement = Arrangement.spacedBy(24.dp)
+                ) {
+                    // Gallery picker button
+                    IconButton(
+                        onClick = {
+                            if (!isCapturing) {
+                                galleryLauncher.launch(
+                                    PickVisualMediaRequest(ActivityResultContracts.PickVisualMedia.ImageOnly)
+                                )
+                            }
+                        },
+                        enabled = !isCapturing,
+                        modifier = Modifier.size(52.dp)
+                    ) {
+                        Icon(
+                            imageVector = Icons.Default.PhotoLibrary,
+                            contentDescription = "Pick from gallery",
+                            tint = Color.White,
+                            modifier = Modifier.size(28.dp)
+                        )
+                    }
+
                     // Capture button
                     CaptureButton(
                         isCapturing = isCapturing,
@@ -311,6 +492,9 @@ fun CameraScreen(
                                         when (result) {
                                             is SaveResult.Success -> {
                                                 haptics.success()
+                                                lastThumbnailBitmap?.recycle()
+                                                lastThumbnailBitmap = result.thumbnail
+                                                lastSavedUri = result.uri
                                                 showSaveSuccess = true
                                                 delay(1500)
                                                 showSaveSuccess = false
@@ -328,7 +512,30 @@ fun CameraScreen(
                             }
                         }
                     )
+
+                    // Spacer for visual symmetry with gallery button
+                    Spacer(modifier = Modifier.size(52.dp))
                 }
+            }
+        }
+
+        // Last captured photo thumbnail (hidden in gallery preview mode)
+        if (!isGalleryPreview) LastPhotoThumbnail(
+            thumbnail = lastThumbnailBitmap,
+            onTap = {
+                lastSavedUri?.let { uri ->
+                    val intent = Intent(Intent.ACTION_VIEW).apply {
+                        setDataAndType(uri, "image/jpeg")
+                        addFlags(Intent.FLAG_GRANT_READ_URI_PERMISSION)
+                    }
+                    context.startActivity(intent)
+                }
+            },
+            modifier = Modifier
+                .align(Alignment.BottomEnd)
+                .navigationBarsPadding()
+                .padding(bottom = 48.dp, end = 16.dp)
+        )
 
         // Success indicator
         AnimatedVisibility(
@@ -484,6 +691,7 @@ private fun ControlPanel(
                 onValueChange = { currentOnParamsChange(currentParams.copy(aspectRatio = it)) }
             )
         }
+
     }
 }
 
@@ -552,3 +760,34 @@ private fun CaptureButton(
         )
     }
 }
+
+/**
+ * Rounded thumbnail of the last captured photo.
+ * Tapping opens the image in the default photo viewer.
+ */
+@Composable
+private fun LastPhotoThumbnail(
+    thumbnail: Bitmap?,
+    onTap: () -> Unit,
+    modifier: Modifier = Modifier
+) {
+    AnimatedVisibility(
+        visible = thumbnail != null,
+        enter = fadeIn() + scaleIn(initialScale = 0.6f),
+        exit = fadeOut(),
+        modifier = modifier
+    ) {
+        thumbnail?.let { bmp ->
+            Image(
+                bitmap = bmp.asImageBitmap(),
+                contentDescription = "Last captured photo",
+                contentScale = ContentScale.Crop,
+                modifier = Modifier
+                    .size(52.dp)
+                    .clip(RoundedCornerShape(10.dp))
+                    .border(2.dp, Color.White, RoundedCornerShape(10.dp))
+                    .clickable(onClick = onTap)
+            )
+        }
+    }
+}

app/src/main/java/no/naiv/tiltshift/ui/LensSwitcher.kt

@@ -9,9 +9,6 @@ import androidx.compose.foundation.layout.Row
 import androidx.compose.foundation.layout.padding
 import androidx.compose.foundation.layout.size
 import androidx.compose.foundation.shape.CircleShape
-import androidx.compose.material.icons.Icons
-import androidx.compose.material.icons.filled.CameraRear
-import androidx.compose.material3.Icon
 import androidx.compose.material3.Text
 import androidx.compose.runtime.Composable
 import androidx.compose.runtime.getValue
@@ -90,28 +87,3 @@ private fun LensButton(
         )
     }
 }
-
-/**
- * Simple camera flip button (for future front camera support).
- */
-@Composable
-fun CameraFlipButton(
-    onClick: () -> Unit,
-    modifier: Modifier = Modifier
-) {
-    Box(
-        modifier = modifier
-            .size(48.dp)
-            .clip(CircleShape)
-            .background(Color(0x80000000))
-            .clickable(onClick = onClick),
-        contentAlignment = Alignment.Center
-    ) {
-        Icon(
-            imageVector = Icons.Default.CameraRear,
-            contentDescription = "Switch Camera",
-            tint = Color.White,
-            modifier = Modifier.size(24.dp)
-        )
-    }
-}

app/src/main/java/no/naiv/tiltshift/util/HapticFeedback.kt

@@ -1,98 +1,55 @@
 package no.naiv.tiltshift.util
 
 import android.content.Context
-import android.os.Build
 import android.os.VibrationEffect
-import android.os.Vibrator
 import android.os.VibratorManager
-import android.view.HapticFeedbackConstants
-import android.view.View
 
 /**
  * Provides haptic feedback for user interactions.
  */
 class HapticFeedback(private val context: Context) {
 
-    private val vibrator: Vibrator by lazy {
+    private val vibrator by lazy {
-        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.S) {
         val vibratorManager = context.getSystemService(Context.VIBRATOR_MANAGER_SERVICE) as VibratorManager
         vibratorManager.defaultVibrator
-        } else {
-            @Suppress("DEPRECATION")
-            context.getSystemService(Context.VIBRATOR_SERVICE) as Vibrator
-        }
     }
 
     /**
      * Light tick for UI feedback (button press, slider change).
      */
     fun tick() {
-        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.Q) {
         vibrator.vibrate(VibrationEffect.createPredefined(VibrationEffect.EFFECT_TICK))
-        } else {
-            @Suppress("DEPRECATION")
-            vibrator.vibrate(10L)
-        }
     }
 
     /**
      * Click feedback for confirmations.
      */
     fun click() {
-        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.Q) {
         vibrator.vibrate(VibrationEffect.createPredefined(VibrationEffect.EFFECT_CLICK))
-        } else {
-            @Suppress("DEPRECATION")
-            vibrator.vibrate(20L)
-        }
     }
 
     /**
      * Heavy click for important actions (photo capture).
      */
     fun heavyClick() {
-        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.Q) {
         vibrator.vibrate(VibrationEffect.createPredefined(VibrationEffect.EFFECT_HEAVY_CLICK))
-        } else {
-            @Suppress("DEPRECATION")
-            vibrator.vibrate(40L)
-        }
     }
 
     /**
      * Success feedback pattern.
      */
     fun success() {
-        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.Q) {
         val timings = longArrayOf(0, 30, 50, 30)
         val amplitudes = intArrayOf(0, 100, 0, 200)
         vibrator.vibrate(VibrationEffect.createWaveform(timings, amplitudes, -1))
-        } else {
-            @Suppress("DEPRECATION")
-            vibrator.vibrate(longArrayOf(0, 30, 50, 30), -1)
-        }
     }
 
     /**
      * Error feedback pattern.
      */
     fun error() {
-        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.Q) {
         val timings = longArrayOf(0, 50, 30, 50, 30, 50)
         val amplitudes = intArrayOf(0, 150, 0, 150, 0, 150)
         vibrator.vibrate(VibrationEffect.createWaveform(timings, amplitudes, -1))
-        } else {
-            @Suppress("DEPRECATION")
-            vibrator.vibrate(longArrayOf(0, 50, 30, 50, 30, 50), -1)
-        }
-    }
-
-    companion object {
-        /**
-         * Use system haptic feedback on a View for standard interactions.
-         */
-        fun performHapticFeedback(view: View, feedbackConstant: Int = HapticFeedbackConstants.VIRTUAL_KEY) {
-            view.performHapticFeedback(feedbackConstant)
-        }
     }
 }