From 89224744e51ea4fee198f7922d755f9a6ba27eb3 Mon Sep 17 00:00:00 2001
From: Benoit Marty <benoit@matrix.org>
Date: Wed, 23 Nov 2022 17:00:16 +0100
Subject: [PATCH 1/3] Optimize lazy column

---
 .../x/features/messages/MessagesScreen.kt     | 22 +++++++++++++++++--
 .../x/features/roomlist/RoomListScreen.kt     |  9 +++++++-
 2 files changed, 28 insertions(+), 3 deletions(-)

diff --git a/features/messages/src/main/java/io/element/android/x/features/messages/MessagesScreen.kt b/features/messages/src/main/java/io/element/android/x/features/messages/MessagesScreen.kt
index eaef076c63..f354dce2b6 100644
--- a/features/messages/src/main/java/io/element/android/x/features/messages/MessagesScreen.kt
+++ b/features/messages/src/main/java/io/element/android/x/features/messages/MessagesScreen.kt
@@ -10,7 +10,7 @@ import androidx.compose.foundation.interaction.MutableInteractionSource
 import androidx.compose.foundation.layout.*
 import androidx.compose.foundation.lazy.LazyColumn
 import androidx.compose.foundation.lazy.LazyListState
-import androidx.compose.foundation.lazy.itemsIndexed
+import androidx.compose.foundation.lazy.items
 import androidx.compose.foundation.lazy.rememberLazyListState
 import androidx.compose.foundation.shape.RoundedCornerShape
 import androidx.compose.material.ExperimentalMaterialApi
@@ -230,7 +230,11 @@ fun TimelineItems(
         verticalArrangement = Arrangement.Bottom,
         reverseLayout = true
     ) {
-        itemsIndexed(timelineItems) { index, timelineItem ->
+        items(
+            items = timelineItems,
+            contentType = { timelineItem -> timelineItem.contentType() },
+            key = { timelineItem -> timelineItem.key() },
+        ) { timelineItem ->
             TimelineItemRow(
                 timelineItem = timelineItem,
                 onClick = onClick,
@@ -245,6 +249,20 @@ fun TimelineItems(
     }
 }
 
+private fun MessagesTimelineItemState.key(): String {
+    return when (this) {
+        is MessagesTimelineItemState.MessageEvent -> id
+        is MessagesTimelineItemState.Virtual -> id
+    }
+}
+
+private fun MessagesTimelineItemState.contentType(): Int {
+    return when (this) {
+        is MessagesTimelineItemState.MessageEvent -> 0
+        is MessagesTimelineItemState.Virtual -> 1
+    }
+}
+
 
 @Composable
 fun TimelineItemRow(
diff --git a/features/roomlist/src/main/java/io/element/android/x/features/roomlist/RoomListScreen.kt b/features/roomlist/src/main/java/io/element/android/x/features/roomlist/RoomListScreen.kt
index 3880339503..fa9ef08a23 100644
--- a/features/roomlist/src/main/java/io/element/android/x/features/roomlist/RoomListScreen.kt
+++ b/features/roomlist/src/main/java/io/element/android/x/features/roomlist/RoomListScreen.kt
@@ -122,7 +122,11 @@ fun RoomListContent(
                         .nestedScroll(nestedScrollConnection),
                     state = lazyListState,
                 ) {
-                    items(roomSummaries) { room ->
+                    items(
+                        items = roomSummaries,
+                        contentType = { room -> room.contentType() },
+                        key = { room -> room.key() },
+                    ) { room ->
                         RoomSummaryRow(room = room, onClick = ::onRoomClicked)
                     }
                 }
@@ -134,6 +138,9 @@ fun RoomListContent(
     }
 }
 
+private fun RoomListRoomSummary.key() = id
+private fun RoomListRoomSummary.contentType() = isPlaceholder
+
 private fun LazyListState.isScrolled(): Boolean {
     return firstVisibleItemIndex > 0 || firstVisibleItemScrollOffset > 0
 }

From 1e4cacb35ba630eb1406b724a59f2ccca3285d25 Mon Sep 17 00:00:00 2001
From: Benoit Marty <benoit@matrix.org>
Date: Wed, 23 Nov 2022 17:30:44 +0100
Subject: [PATCH 2/3] Add small list of links.

---
 docs/usefulLinks.md | 6 ++++++
 1 file changed, 6 insertions(+)
 create mode 100644 docs/usefulLinks.md

diff --git a/docs/usefulLinks.md b/docs/usefulLinks.md
new file mode 100644
index 0000000000..533184e21f
--- /dev/null
+++ b/docs/usefulLinks.md
@@ -0,0 +1,6 @@
+
+### Jetpack Compose
+
+https://developer.android.com/jetpack/compose/mental-model
+    
+https://android.googlesource.com/platform/frameworks/support/+/androidx-main/compose/docs/compose-api-guidelines.md#api-guidelines-for-jetpack-compose
\ No newline at end of file

From c15b625d94d333f927d1a1d1e2d6ef593c61d1fc Mon Sep 17 00:00:00 2001
From: Benoit Marty <benoit@matrix.org>
Date: Wed, 23 Nov 2022 17:33:06 +0100
Subject: [PATCH 3/3] Do not use key to ensure that the list scroll if a room
 appears at the top

---
 .../io/element/android/x/features/roomlist/RoomListScreen.kt    | 2 --
 1 file changed, 2 deletions(-)

diff --git a/features/roomlist/src/main/java/io/element/android/x/features/roomlist/RoomListScreen.kt b/features/roomlist/src/main/java/io/element/android/x/features/roomlist/RoomListScreen.kt
index fa9ef08a23..85fd887373 100644
--- a/features/roomlist/src/main/java/io/element/android/x/features/roomlist/RoomListScreen.kt
+++ b/features/roomlist/src/main/java/io/element/android/x/features/roomlist/RoomListScreen.kt
@@ -125,7 +125,6 @@ fun RoomListContent(
                     items(
                         items = roomSummaries,
                         contentType = { room -> room.contentType() },
-                        key = { room -> room.key() },
                     ) { room ->
                         RoomSummaryRow(room = room, onClick = ::onRoomClicked)
                     }
@@ -138,7 +137,6 @@ fun RoomListContent(
     }
 }
 
-private fun RoomListRoomSummary.key() = id
 private fun RoomListRoomSummary.contentType() = isPlaceholder
 
 private fun LazyListState.isScrolled(): Boolean {