lazy build perf improvements: build extent from screen size + factor in scaling + refactor

2025-07-05 21:48:32 +00:00
parent b81b99c55c
commit f01363e72d
3 changed files with 72 additions and 19 deletions
@@ -0,0 +1,39 @@
+import 'package:flutter/material.dart';
+import 'package:flutter/scheduler.dart';
+
+class Fps extends StatefulWidget {
+  const Fps({super.key});
+
+  @override
+  State<Fps> createState() => _FpsState();
+}
+
+class _FpsState extends State<Fps> {
+  @override
+  void initState() {
+    SchedulerBinding.instance.addPersistentFrameCallback(_frame);
+    super.initState();
+  }
+
+  int _lastFrameTime = 0;
+  String _frameRate = "0 fps";
+  void _frame(Duration elapsed) {
+    int elapsedMicroseconds = elapsed.inMicroseconds;
+    double elapsedSeconds = (elapsedMicroseconds - _lastFrameTime) * 1e-6;
+    if (elapsedSeconds != 0) {
+      _lastFrameTime = elapsedMicroseconds;
+      setState(() {
+        _frameRate = '${(1.0 / elapsedSeconds).toStringAsFixed(2)} fps';
+      });
+    }
+    // redraw if mounted
+    if (mounted) {
+      SchedulerBinding.instance.scheduleFrame();
+    }
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    return Text(_frameRate);
+  }
+}