fix: reduce rebuild for online state (#9331)

* fix: reduce rebuild for online state

Signed-off-by: fufesou <linlong1266@gmail.com>

* Query online, update  on focus changed

Signed-off-by: fufesou <linlong1266@gmail.com>

* Use  to ensure  is right

Signed-off-by: fufesou <linlong1266@gmail.com>

* refact, window events on peer view

Signed-off-by: fufesou <linlong1266@gmail.com>

* chore

Signed-off-by: fufesou <linlong1266@gmail.com>

* Remove unused code

Signed-off-by: fufesou <linlong1266@gmail.com>

---------

Signed-off-by: fufesou <linlong1266@gmail.com>

flutter/lib/common/widgets/peers_view.dart

@@ -89,6 +89,7 @@ class _PeersViewState extends State<_PeersView>
   var _lastChangeTime = DateTime.now();
   var _lastQueryPeers = <String>{};
   var _lastQueryTime = DateTime.now();
+  var _lastWindowRestoreTime = DateTime.now();
   var _queryCount = 0;
   var _exit = false;
   bool _isActive = true;
@@ -117,11 +118,37 @@ class _PeersViewState extends State<_PeersView>
   @override
   void onWindowFocus() {
     _queryCount = 0;
+    _isActive = true;
+  }
+
+  @override
+  void onWindowBlur() {
+    // We need this comparison because window restore (on Windows) also triggers `onWindowBlur()`.
+    // Maybe it's a bug of the window manager, but the source code seems to be correct.
+    //
+    // Although `onWindowRestore()` is called after `onWindowBlur()` in my test,
+    // we need the following comparison to ensure that `_isActive` is true in the end.
+    if (isWindows && DateTime.now().difference(_lastWindowRestoreTime) <
+        const Duration(milliseconds: 300)) {
+      return;
+    }
+    _queryCount = _maxQueryCount;
+    _isActive = false;
+  }
+
+  @override
+  void onWindowRestore() {
+    // Window restore (on MacOS and Linux) also triggers `onWindowFocus()`.
+    // But on Windows, it triggers `onWindowBlur()`, mybe it's a bug of the window manager.
+    if (!isWindows) return;
+    _queryCount = 0;
+    _isActive = true;
+    _lastWindowRestoreTime = DateTime.now();
   }
 
   @override
   void onWindowMinimize() {
-    _queryCount = _maxQueryCount;
+    // Window minimize also triggers `onWindowBlur()`.
   }
 
   // This function is required for mobile.
@@ -234,7 +261,8 @@ class _PeersViewState extends State<_PeersView>
                             physics: DraggableNeverScrollableScrollPhysics(),
                             itemCount: peers.length,
                             itemBuilder: (BuildContext context, int index) {
-                              return buildOnePeer(peers[index], false).marginOnly(
+                              return buildOnePeer(peers[index], false)
+                                  .marginOnly(
                                       right: space,
                                       top: index == 0 ? 0 : space / 2,
                                       bottom: space / 2);

flutter/lib/models/peer_model.dart

@@ -194,25 +194,34 @@ class Peers extends ChangeNotifier {
   }
 
   void _updateOnlineState(Map<String, dynamic> evt) {
+    int changedCount = 0;
     evt['onlines'].split(',').forEach((online) {
       for (var i = 0; i < peers.length; i++) {
         if (peers[i].id == online) {
+          if (!peers[i].online) {
+            changedCount += 1;
             peers[i].online = true;
           }
         }
+      }
     });
 
     evt['offlines'].split(',').forEach((offline) {
       for (var i = 0; i < peers.length; i++) {
         if (peers[i].id == offline) {
+          if (peers[i].online) {
+            changedCount += 1;
             peers[i].online = false;
           }
         }
+      }
     });
 
+    if (changedCount > 0) {
       event = UpdateEvent.online;
       notifyListeners();
     }
+  }
 
   void _updatePeers(Map<String, dynamic> evt) {
     final onlineStates = _getOnlineStates();