Add ability to swipe between media when opened from the timeline.

libraries/matrix/api/src/main/kotlin/io/element/android/libraries/matrix/api/room/MatrixRoom.kt

@@ -118,8 +118,9 @@ interface MatrixRoom : Closeable {
 
     /**
      * Create a new timeline for the media events of the room.
+     * @param eventId The event to focus on, if any.
      */
-    suspend fun mediaTimeline(): Result<Timeline>
+    suspend fun mediaTimeline(eventId: EventId?): Result<Timeline>
 
     fun destroy()
 

libraries/matrix/impl/src/main/kotlin/io/element/android/libraries/matrix/impl/room/RustMatrixRoom.kt

@@ -253,11 +253,21 @@ class RustMatrixRoom(
         }
     }
 
-    override suspend fun mediaTimeline(): Result<Timeline> = withContext(roomDispatcher) {
+    override suspend fun mediaTimeline(
+        eventId: EventId?,
+    ): Result<Timeline> = withContext(roomDispatcher) {
+        val focus = if (eventId != null) {
+            TimelineFocus.Event(
+                eventId = eventId.value,
+                numContextEvents = 50u,
+            )
+        } else {
+            TimelineFocus.Live
+        }
         runCatching {
             innerRoom.timelineWithConfiguration(
                 configuration = TimelineConfiguration(
-                    focus = TimelineFocus.Live,
+                    focus = focus,
                     allowedMessageTypes = AllowedMessageTypes.Only(
                         types = listOf(
                             RoomMessageEventMessageType.FILE,
@@ -270,7 +280,7 @@ class RustMatrixRoom(
                     dateDividerMode = DateDividerMode.MONTHLY,
                 )
             ).let { inner ->
-                createTimeline(inner, mode = Timeline.Mode.MEDIA)
+                createTimeline(inner, mode = if (eventId != null) Timeline.Mode.FOCUSED_ON_EVENT else Timeline.Mode.MEDIA)
             }
         }.onFailure {
             if (it is CancellationException) {

libraries/matrix/test/src/main/kotlin/io/element/android/libraries/matrix/test/room/FakeMatrixRoom.kt

@@ -137,7 +137,7 @@ class FakeMatrixRoom(
     private val getMembersResult: (Int) -> Result<List<RoomMember>> = { lambdaError() },
     private val timelineFocusedOnEventResult: (EventId) -> Result<Timeline> = { lambdaError() },
     private val pinnedEventsTimelineResult: () -> Result<Timeline> = { lambdaError() },
-    private val mediaTimelineResult: () -> Result<Timeline> = { lambdaError() },
+    private val mediaTimelineResult: (EventId?) -> Result<Timeline> = { lambdaError() },
     private val setSendQueueEnabledLambda: (Boolean) -> Unit = { _: Boolean -> },
     private val saveComposerDraftLambda: (ComposerDraft) -> Result<Unit> = { _: ComposerDraft -> Result.success(Unit) },
     private val loadComposerDraftLambda: () -> Result<ComposerDraft?> = { Result.success<ComposerDraft?>(null) },
@@ -215,8 +215,8 @@ class FakeMatrixRoom(
         pinnedEventsTimelineResult()
     }
 
-    override suspend fun mediaTimeline(): Result<Timeline> = simulateLongTask {
-        mediaTimelineResult()
+    override suspend fun mediaTimeline(eventId: EventId?): Result<Timeline> = simulateLongTask {
+        mediaTimelineResult(eventId)
     }
 
     override suspend fun subscribeToSync() {