Use lifecycle-scoped IO for screen work

app/src/main/java/se/ajpanton/notificationlog/ImageViewerDialogFragment.kt

@@ -19,7 +19,11 @@ import androidx.core.view.WindowCompat
 import androidx.core.view.WindowInsetsCompat
 import androidx.core.view.WindowInsetsControllerCompat
 import androidx.fragment.app.DialogFragment
+import androidx.lifecycle.lifecycleScope
 import se.ajpanton.notificationlog.data.EncryptedImageStore
+import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.launch
+import kotlinx.coroutines.withContext
 
 /** Full-screen image viewer kept within MainActivity so opening it does not re-lock the app. */
 class ImageViewerDialogFragment : DialogFragment() {
@@ -67,27 +71,25 @@ class ImageViewerDialogFragment : DialogFragment() {
         val targetWidth = resources.displayMetrics.widthPixels
         val targetHeight = resources.displayMetrics.heightPixels
         val appContext = requireContext().applicationContext
-        Thread {
-            val bitmap = runCatching {
+        lifecycleScope.launch {
+            val bitmap = withContext(Dispatchers.IO) { runCatching {
                 EncryptedImageStore(appContext).read(imageId)?.let { bytes ->
                     decodeForViewer(bytes, targetWidth, targetHeight)
                 }
-            }.getOrNull()
-            activity?.runOnUiThread {
-                if (!isAdded) return@runOnUiThread
-                progress.visibility = View.GONE
-                if (bitmap == null) {
-                    root.addView(TextView(requireContext()).apply {
-                        text = "[image]"
-                        setTextColor(Color.WHITE)
-                        textSize = 18f
-                    }, FrameLayout.LayoutParams(ViewGroup.LayoutParams.WRAP_CONTENT, ViewGroup.LayoutParams.WRAP_CONTENT, Gravity.CENTER))
-                } else {
-                    image.setImageBitmap(bitmap)
-                    image.visibility = View.VISIBLE
-                }
+            }.getOrNull() }
+            if (!isAdded) return@launch
+            progress.visibility = View.GONE
+            if (bitmap == null) {
+                root.addView(TextView(requireContext()).apply {
+                    text = "[image]"
+                    setTextColor(Color.WHITE)
+                    textSize = 18f
+                }, FrameLayout.LayoutParams(ViewGroup.LayoutParams.WRAP_CONTENT, ViewGroup.LayoutParams.WRAP_CONTENT, Gravity.CENTER))
+            } else {
+                image.setImageBitmap(bitmap)
+                image.visibility = View.VISIBLE
             }
-        }.start()
+        }
     }
 
     private fun decodeForViewer(bytes: ByteArray, targetWidth: Int, targetHeight: Int): Bitmap? {