Create the LocalMedia off the main thread when picking or sharing media

LocalMediaFactory.createFromUri queries the ContentResolver and can decode the media, it was called on the main thread from the picker callbacks and when sharing a file.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

features/messages/impl/src/main/kotlin/io/element/android/features/messages/impl/messagecomposer/MessageComposerPresenter.kt

@@ -43,6 +43,7 @@ import io.element.android.features.messages.impl.timeline.TimelineController
 import io.element.android.features.messages.impl.utils.TextPillificationHelper
 import io.element.android.libraries.architecture.AsyncAction
 import io.element.android.libraries.architecture.Presenter
+import io.element.android.libraries.core.coroutine.CoroutineDispatchers
 import io.element.android.libraries.core.extensions.runCatchingExceptions
 import io.element.android.libraries.core.mimetype.MimeTypes
 import io.element.android.libraries.designsystem.utils.snackbar.SnackbarDispatcher
@@ -110,6 +111,7 @@ import kotlinx.coroutines.flow.map
 import kotlinx.coroutines.flow.merge
 import kotlinx.coroutines.flow.stateIn
 import kotlinx.coroutines.launch
+import kotlinx.coroutines.withContext
 import timber.log.Timber
 import kotlin.time.Duration.Companion.seconds
 import io.element.android.libraries.core.mimetype.MimeTypes.Any as AnyMimeTypes
@@ -145,6 +147,7 @@ class MessageComposerPresenter(
     private val featureFlagService: FeatureFlagService,
     private val contentScannerService: ContentScannerService,
     private val contentValidationCache: EventContentValidationCache,
+    private val dispatchers: CoroutineDispatchers,
 ) : Presenter<MessageComposerState> {
     @AssistedFactory
     interface Factory {
@@ -193,22 +196,22 @@ class MessageComposerPresenter(
             .collectAsState(initial = false)
 
         val galleryMediaPicker = mediaPickerProvider.registerGalleryPicker { uri, mimeType ->
-            handlePickedMedia(uri, mimeType)
+            localCoroutineScope.handlePickedMedia(uri, mimeType)
         }
         val galleryMultiMediaPicker = mediaPickerProvider.registerGalleryMultiPicker { uris ->
-            handlePickedMediaList(uris)
+            localCoroutineScope.handlePickedMediaList(uris)
         }
         val filesPicker = mediaPickerProvider.registerFileMultiPicker(AnyMimeTypes) { uris ->
-            handlePickedMediaList(uris, sendAsFile = true)
+            localCoroutineScope.handlePickedMediaList(uris, sendAsFile = true)
         }
         val fileSinglePicker = mediaPickerProvider.registerFilePicker(AnyMimeTypes) { uri, mimeType ->
-            handlePickedMedia(uri, mimeType ?: MimeTypes.OctetStream, sendAsFile = true)
+            localCoroutineScope.handlePickedMedia(uri, mimeType ?: MimeTypes.OctetStream, sendAsFile = true)
         }
         val cameraPhotoPicker = mediaPickerProvider.registerCameraPhotoPicker { uri ->
-            handlePickedMedia(uri, MimeTypes.Jpeg)
+            localCoroutineScope.handlePickedMedia(uri, MimeTypes.Jpeg)
         }
         val cameraVideoPicker = mediaPickerProvider.registerCameraVideoPicker { uri ->
-            handlePickedMedia(uri, MimeTypes.Mp4)
+            localCoroutineScope.handlePickedMedia(uri, MimeTypes.Mp4)
         }
         val isFullScreen = rememberSaveable {
             mutableStateOf(false)
@@ -286,17 +289,16 @@ class MessageComposerPresenter(
                 }
                 is MessageComposerEvent.SendUri -> {
                     val inReplyToEventId = (messageComposerContext.composerMode as? MessageComposerMode.Reply)?.eventId
-                    sessionCoroutineScope.sendAttachment(
-                        attachment = Attachment.Media(
-                            localMedia = localMediaFactory.createFromUri(
-                                uri = event.uri,
-                                mimeType = null,
-                                name = null,
-                                formattedFileSize = null
-                            ),
-                        ),
-                        inReplyToEventId = inReplyToEventId,
-                    )
+                    sessionCoroutineScope.launch {
+                        val localMedia = createLocalMedia(
+                            uri = event.uri,
+                            mimeType = null,
+                        )
+                        sendAttachment(
+                            attachment = Attachment.Media(localMedia),
+                            inReplyToEventId = inReplyToEventId,
+                        )
+                    }
 
                     resetComposerModeAfterAttaching()
                 }
@@ -640,17 +642,28 @@ class MessageComposerPresenter(
         }
     }
 
-    private fun handlePickedMedia(
-        uri: Uri?,
-        mimeType: String? = null,
-        sendAsFile: Boolean = false,
-    ) {
-        uri ?: return
-        val localMedia = localMediaFactory.createFromUri(
+    // Creating the LocalMedia queries the ContentResolver and can decode the media, so do it off the main thread
+    private suspend fun createLocalMedia(
+        uri: Uri,
+        mimeType: String?,
+    ) = withContext(dispatchers.io) {
+        localMediaFactory.createFromUri(
             uri = uri,
             mimeType = mimeType,
             name = null,
-            formattedFileSize = null
+            formattedFileSize = null,
+        )
+    }
+
+    private fun CoroutineScope.handlePickedMedia(
+        uri: Uri?,
+        mimeType: String? = null,
+        sendAsFile: Boolean = false,
+    ) = launch {
+        uri ?: return@launch
+        val localMedia = createLocalMedia(
+            uri = uri,
+            mimeType = mimeType,
         )
         val mediaAttachment = Attachment.Media(localMedia, sendAsFile = sendAsFile)
         val inReplyToEventId = (messageComposerContext.composerMode as? MessageComposerMode.Reply)?.eventId
@@ -659,7 +672,7 @@ class MessageComposerPresenter(
         resetComposerModeAfterAttaching()
     }
 
-    private fun handlePickedMediaList(
+    private fun CoroutineScope.handlePickedMediaList(
         uris: List<Uri>,
         sendAsFile: Boolean = false,
     ) {
@@ -668,19 +681,19 @@ class MessageComposerPresenter(
             handlePickedMedia(uris.first(), sendAsFile = sendAsFile)
             return
         }
-        val attachments = uris.map { uri ->
-            val localMedia = localMediaFactory.createFromUri(
-                uri = uri,
-                mimeType = null,
-                name = null,
-                formattedFileSize = null,
-            )
-            Attachment.Media(localMedia, sendAsFile = sendAsFile)
-        }.toImmutableList()
-        val inReplyToEventId = (messageComposerContext.composerMode as? MessageComposerMode.Reply)?.eventId
-        navigator.navigateToPreviewAttachments(attachments, inReplyToEventId)
+        launch {
+            val attachments = uris.map { uri ->
+                val localMedia = createLocalMedia(
+                    uri = uri,
+                    mimeType = null,
+                )
+                Attachment.Media(localMedia, sendAsFile = sendAsFile)
+            }.toImmutableList()
+            val inReplyToEventId = (messageComposerContext.composerMode as? MessageComposerMode.Reply)?.eventId
+            navigator.navigateToPreviewAttachments(attachments, inReplyToEventId)
 
-        resetComposerModeAfterAttaching()
+            resetComposerModeAfterAttaching()
+        }
     }
 
     private fun resetComposerModeAfterAttaching() {

features/messages/impl/src/test/kotlin/io/element/android/features/messages/impl/messagecomposer/MessageComposerPresenterSlashCommandTest.kt

@@ -324,6 +324,7 @@ class MessageComposerPresenterSlashCommandTest {
         featureFlagService = featureFlagService,
         contentScannerService = { _, _ -> },
         contentValidationCache = InMemoryEventContentValidationCache(),
+        dispatchers = testCoroutineDispatchers(useUnconfinedTestDispatcher = true),
     ).apply {
         isTesting = true
         showTextFormatting = isRichTextEditorEnabled

features/messages/impl/src/test/kotlin/io/element/android/features/messages/impl/messagecomposer/MessageComposerPresenterTest.kt

@@ -1723,6 +1723,7 @@ class MessageComposerPresenterTest : RobolectricTest() {
         featureFlagService = featureFlagService,
         contentScannerService = { _, _ -> },
         contentValidationCache = InMemoryEventContentValidationCache(),
+        dispatchers = testCoroutineDispatchers(useUnconfinedTestDispatcher = true),
     ).apply {
         isTesting = true
         showTextFormatting = isRichTextEditorEnabled