Add bitmap safety in applyTiltShiftEffect()

Track all intermediate bitmaps with nullable variables and recycle
them in a finally block. This prevents native memory leaks when an
OOM or other exception occurs mid-processing. Variables are set to
null after recycle or handoff to the caller.

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

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

@@ -152,63 +152,81 @@ class ImageCaptureHandler(
     /**
      * 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
-        val result = Bitmap.createBitmap(width, height, Bitmap.Config.ARGB_8888)
+        var result: Bitmap? = null
+        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
-        val scaleFactor = 4 // Blur a 1/4 size image for speed
-        val blurredWidth = width / scaleFactor
-        val blurredHeight = height / scaleFactor
+        try {
+            result = Bitmap.createBitmap(width, height, Bitmap.Config.ARGB_8888)
 
-        // Create scaled bitmap for blur
-        val scaled = Bitmap.createScaledBitmap(source, blurredWidth, blurredHeight, true)
+            val scaleFactor = 4
+            val blurredWidth = width / scaleFactor
+            val blurredHeight = height / scaleFactor
 
-        // Apply stack blur (fast approximation)
-        val blurred = stackBlur(scaled, (params.blurAmount * 25).toInt().coerceIn(1, 25))
-        scaled.recycle()
+            scaled = Bitmap.createScaledBitmap(source, blurredWidth, blurredHeight, true)
 
-        // Scale blurred back up
-        val blurredFullSize = Bitmap.createScaledBitmap(blurred, width, height, true)
-        blurred.recycle()
+            blurred = stackBlur(scaled, (params.blurAmount * 25).toInt().coerceIn(1, 25))
+            scaled.recycle()
+            scaled = null
 
-        // Create gradient mask based on tilt-shift parameters
-        val mask = createGradientMask(width, height, params)
+            blurredFullSize = Bitmap.createScaledBitmap(blurred, width, height, true)
+            blurred.recycle()
+            blurred = null
 
-        // Composite: blend original with blurred based on mask
-        val pixels = IntArray(width * height)
-        val blurredPixels = IntArray(width * height)
-        val maskPixels = IntArray(width * height)
+            mask = createGradientMask(width, height, params)
 
-        source.getPixels(pixels, 0, width, 0, 0, width, height)
-        blurredFullSize.getPixels(blurredPixels, 0, width, 0, 0, width, height)
-        mask.getPixels(maskPixels, 0, width, 0, 0, width, height)
+            // Composite: blend original with blurred based on mask
+            val pixels = IntArray(width * height)
+            val blurredPixels = IntArray(width * height)
+            val maskPixels = IntArray(width * height)
 
-        blurredFullSize.recycle()
-        mask.recycle()
+            source.getPixels(pixels, 0, width, 0, 0, width, height)
+            blurredFullSize.getPixels(blurredPixels, 0, width, 0, 0, width, height)
+            mask.getPixels(maskPixels, 0, width, 0, 0, width, height)
 
-        for (i in pixels.indices) {
-            val maskAlpha = (maskPixels[i] and 0xFF) / 255f
-            val origR = (pixels[i] shr 16) and 0xFF
-            val origG = (pixels[i] shr 8) and 0xFF
-            val origB = pixels[i] and 0xFF
-            val blurR = (blurredPixels[i] shr 16) and 0xFF
-            val blurG = (blurredPixels[i] shr 8) and 0xFF
-            val blurB = blurredPixels[i] and 0xFF
+            blurredFullSize.recycle()
+            blurredFullSize = null
+            mask.recycle()
+            mask = null
 
-            val r = (origR * (1 - maskAlpha) + blurR * maskAlpha).toInt()
-            val g = (origG * (1 - maskAlpha) + blurG * maskAlpha).toInt()
-            val b = (origB * (1 - maskAlpha) + blurB * maskAlpha).toInt()
+            for (i in pixels.indices) {
+                val maskAlpha = (maskPixels[i] and 0xFF) / 255f
+                val origR = (pixels[i] shr 16) and 0xFF
+                val origG = (pixels[i] shr 8) and 0xFF
+                val origB = pixels[i] and 0xFF
+                val blurR = (blurredPixels[i] shr 16) and 0xFF
+                val blurG = (blurredPixels[i] shr 8) and 0xFF
+                val blurB = blurredPixels[i] and 0xFF
 
-            pixels[i] = (0xFF shl 24) or (r shl 16) or (g shl 8) or b
+                val r = (origR * (1 - maskAlpha) + blurR * maskAlpha).toInt()
+                val g = (origG * (1 - maskAlpha) + blurG * maskAlpha).toInt()
+                val b = (origB * (1 - maskAlpha) + blurB * maskAlpha).toInt()
+
+                pixels[i] = (0xFF shl 24) or (r shl 16) or (g shl 8) or b
+            }
+
+            result.setPixels(pixels, 0, width, 0, 0, width, height)
+
+            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()
         }
-
-        result.setPixels(pixels, 0, width, 0, 0, width, height)
-        return result
     }
 
     /**