fix: More stable scroll up to event

lib/pages/chat/chat.dart

@@ -275,9 +275,19 @@ class ChatController extends State<ChatPageWithRoom> {
     if (timeline?.allowNewEvent == false ||
         scrollController.position.pixels > 0 && _scrolledUp == false) {
       setState(() => _scrolledUp = true);
-    } else if (scrollController.position.pixels == 0 && _scrolledUp == true) {
+    } else if (scrollController.position.pixels <= 0 && _scrolledUp == true) {
       setState(() => _scrolledUp = false);
     }
+
+    if (scrollController.position.pixels == 0 ||
+        scrollController.position.pixels == 64) {
+      requestFuture();
+    } else if (scrollController.position.pixels ==
+            scrollController.position.maxScrollExtent ||
+        scrollController.position.pixels + 64 ==
+            scrollController.position.maxScrollExtent) {
+      requestHistory();
+    }
   }
 
   void _loadDraft() async {
@@ -904,7 +914,7 @@ class ChatController extends State<ChatPageWithRoom> {
     }
     await scrollController.scrollToIndex(
       eventIndex,
-      preferPosition: AutoScrollPosition.end,
+      preferPosition: AutoScrollPosition.middle,
     );
     _updateScrollController();
   }

lib/pages/chat/chat_event_list.dart

@@ -53,18 +53,11 @@ class ChatEventList extends StatelessWidget {
               );
             }
             if (controller.timeline!.canRequestFuture) {
-              return Builder(
-                builder: (context) {
-                  WidgetsBinding.instance.addPostFrameCallback(
-                    (_) => controller.requestFuture(),
-                  );
-                  return Center(
-                    child: IconButton(
-                      onPressed: controller.requestFuture,
-                      icon: const Icon(Icons.refresh_outlined),
-                    ),
-                  );
-                },
+              return Center(
+                child: IconButton(
+                  onPressed: controller.requestFuture,
+                  icon: const Icon(Icons.refresh_outlined),
+                ),
               );
             }
             return Column(
@@ -84,18 +77,11 @@ class ChatEventList extends StatelessWidget {
               );
             }
             if (controller.timeline!.canRequestHistory) {
-              return Builder(
-                builder: (context) {
-                  WidgetsBinding.instance.addPostFrameCallback(
-                    (_) => controller.requestHistory(),
-                  );
-                  return Center(
-                    child: IconButton(
-                      onPressed: controller.requestHistory,
-                      icon: const Icon(Icons.refresh_outlined),
-                    ),
-                  );
-                },
+              return Center(
+                child: IconButton(
+                  onPressed: controller.requestHistory,
+                  icon: const Icon(Icons.refresh_outlined),
+                ),
               );
             }
             return const SizedBox.shrink();