perf(legacy): skip the native bounds read when setBounds gets a full Rect

lib/src/legacy/window_manager.dart

@@ -4,7 +4,8 @@ import 'dart:async';
 import 'dart:io';
 import 'dart:ui' show Brightness, Color, Offset, PlatformDispatcher, Rect, Size;
 
-import 'package:flutter/foundation.dart' show ObserverList, VoidCallback;
+import 'package:flutter/foundation.dart'
+    show ObserverList, VoidCallback, visibleForTesting;
 import 'package:flutter/painting.dart' show Alignment;
 import 'package:nativeapi/nativeapi.dart' as nativeapi;
 import 'package:nativeapi_flutter/nativeapi_flutter.dart'
@@ -66,6 +67,15 @@ class WindowManager {
   nativeapi.Window? _window;
   nativeapi.ListenerId? _nativeListenerId;
 
+  /// Addresses [window] instead of the platform's current window, or goes
+  /// back to the current window with null. For tests of this bridge only.
+  @visibleForTesting
+  void debugBindWindow(nativeapi.Window? window) {
+    _unwireNativeEvents();
+    _window = window;
+    if (_listeners.isNotEmpty || _isPreventClose) _wireNativeEvents();
+  }
+
   bool _isPreventClose = false;
   bool _isDestroying = false;
   bool _isMaximized = false;
@@ -397,15 +407,20 @@ class WindowManager {
     final window = _target;
     if (window == null) return;
     if (bounds == null && position == null && size == null) return;
-    final current = window.bounds.toRect();
-    final target =
-        bounds ??
-        Rect.fromLTWH(
-          position?.dx ?? current.left,
-          position?.dy ?? current.top,
-          size?.width ?? current.width,
-          size?.height ?? current.height,
-        );
+    // Full bounds are already known: reading them again through nativeapi
+    // performs an unnecessary synchronous FFI call on every restore/move.
+    Rect target;
+    if (bounds != null) {
+      target = bounds;
+    } else {
+      final current = window.bounds.toRect();
+      target = Rect.fromLTWH(
+        position?.dx ?? current.left,
+        position?.dy ?? current.top,
+        size?.width ?? current.width,
+        size?.height ?? current.height,
+      );
+    }
     if (!animate || !window.animateBounds(target.toNative())) {
       window.bounds = target.toNative();
     }

test/legacy_set_bounds_test.dart

@@ -0,0 +1,113 @@
+// ignore_for_file: deprecated_member_use_from_same_package
+
+import 'dart:ui' show Offset, Rect, Size;
+
+import 'package:flutter_test/flutter_test.dart';
+import 'package:nativeapi/nativeapi.dart' as nativeapi;
+import 'package:window_manager/legacy.dart';
+
+// A nativeapi window simulated in Dart; no native window is created.
+class _FakeNativeWindow extends nativeapi.Window {
+  _FakeNativeWindow() : super.borrowed(0);
+
+  int boundsReads = 0;
+  nativeapi.Rectangle currentBounds = const nativeapi.Rectangle(
+    x: 1,
+    y: 2,
+    width: 300,
+    height: 200,
+  );
+
+  @override
+  nativeapi.Rectangle get bounds {
+    boundsReads++;
+    return currentBounds;
+  }
+
+  @override
+  set bounds(nativeapi.Rectangle value) {
+    currentBounds = value;
+  }
+
+  // Simulates a platform without native bounds animation (Windows/Linux).
+  final List<nativeapi.Rectangle> animateRequests = [];
+
+  @override
+  bool animateBounds(nativeapi.Rectangle bounds) {
+    animateRequests.add(bounds);
+    return false;
+  }
+}
+
+void main() {
+  late _FakeNativeWindow native;
+
+  setUp(() {
+    native = _FakeNativeWindow();
+    windowManager.debugBindWindow(native);
+  });
+
+  tearDown(() => windowManager.debugBindWindow(null));
+
+  test('full bounds are applied without reading the window bounds', () async {
+    await windowManager.setBounds(const Rect.fromLTWH(40, 70, 800, 600));
+    expect(native.boundsReads, 0);
+    expect(
+      native.currentBounds,
+      const nativeapi.Rectangle(x: 40, y: 70, width: 800, height: 600),
+    );
+  });
+
+  test('partial updates still read the omitted dimensions', () async {
+    await windowManager.setBounds(null, position: const Offset(25, 35));
+    expect(native.boundsReads, 1);
+    expect(
+      native.currentBounds,
+      const nativeapi.Rectangle(x: 25, y: 35, width: 300, height: 200),
+    );
+
+    await windowManager.setBounds(null, size: const Size(640, 480));
+    expect(native.boundsReads, 2);
+    expect(
+      native.currentBounds,
+      const nativeapi.Rectangle(x: 25, y: 35, width: 640, height: 480),
+    );
+  });
+
+  test('full bounds win over position and size', () async {
+    await windowManager.setBounds(
+      const Rect.fromLTWH(5, 6, 700, 500),
+      position: const Offset(99, 99),
+      size: const Size(1, 1),
+    );
+    expect(native.boundsReads, 0);
+    expect(
+      native.currentBounds,
+      const nativeapi.Rectangle(x: 5, y: 6, width: 700, height: 500),
+    );
+  });
+
+  test('animate falls back to a plain set when refused', () async {
+    await windowManager.setBounds(
+      const Rect.fromLTWH(10, 20, 900, 650),
+      animate: true,
+    );
+    expect(native.boundsReads, 0);
+    expect(native.animateRequests, [
+      const nativeapi.Rectangle(x: 10, y: 20, width: 900, height: 650),
+    ]);
+    expect(
+      native.currentBounds,
+      const nativeapi.Rectangle(x: 10, y: 20, width: 900, height: 650),
+    );
+  });
+
+  test('an empty request is a no-op', () async {
+    await windowManager.setBounds(null);
+    expect(native.boundsReads, 0);
+    expect(
+      native.currentBounds,
+      const nativeapi.Rectangle(x: 1, y: 2, width: 300, height: 200),
+    );
+  });
+}