refactor: More reliable request history/future timeline mechanism

lib/pages/chat/chat.dart

@@ -204,6 +204,7 @@ class ChatController extends State<ChatPageWithRoom> {
 
   void requestHistory() async {
     if (!timeline!.canRequestHistory) return;
+    Logs().v('Requesting history...');
     try {
       await timeline!.requestHistory(historyCount: _loadHistoryCount);
     } catch (err) {
@@ -222,6 +223,7 @@ class ChatController extends State<ChatPageWithRoom> {
     final timeline = this.timeline;
     if (timeline == null) return;
     if (!timeline.canRequestFuture) return;
+    Logs().v('Requesting future...');
     try {
       final mostRecentEventId = timeline.events.first.eventId;
       await timeline.requestFuture(historyCount: _loadHistoryCount);
@@ -244,12 +246,6 @@ class ChatController extends State<ChatPageWithRoom> {
     }
     setReadMarker();
     if (!scrollController.hasClients) return;
-    if (scrollController.position.pixels ==
-        scrollController.position.maxScrollExtent) {
-      requestHistory();
-    } else if (scrollController.position.pixels == 0) {
-      requestFuture();
-    }
     if (timeline?.allowNewEvent == false ||
         scrollController.position.pixels > 0 && _scrolledUp == false) {
       setState(() => _scrolledUp = true);

lib/pages/chat/chat_event_list.dart

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