Add window centering functionality

Introduces a new method to center windows on the primary display in the Dart API, updates native bindings to expose `native_window_center`, and includes necessary C++ implementation files in iOS and macOS builds. This improves window management and user experience by allowing easy window centering.

Author: lijy91

packages/cnativeapi/cxx_impl

@@ -47,3 +47,4 @@
 #include "../../../../cxx_impl/src/secure_storage.cpp"
 #include "../../../../cxx_impl/src/tray_manager.cpp"
 #include "../../../../cxx_impl/src/window_manager.cpp"
+#include "../../../../cxx_impl/src/window_registry.cpp"

packages/cnativeapi/ios/cnativeapi/Sources/cnativeapi/cnativeapi.mm

@@ -14,6 +14,7 @@
 #include "../../../../../cxx_impl/src/foundation/geometry.h"
 #include "../../../../../cxx_impl/src/foundation/id_allocator.h"
 #include "../../../../../cxx_impl/src/foundation/native_object_provider.h"
+#include "../../../../../cxx_impl/src/foundation/object_registry.h"
 #include "../../../../../cxx_impl/src/image.h"
 #include "../../../../../cxx_impl/src/keyboard_event.h"
 #include "../../../../../cxx_impl/src/keyboard_monitor.h"
@@ -31,6 +32,7 @@
 #include "../../../../../cxx_impl/src/window.h"
 #include "../../../../../cxx_impl/src/window_event.h"
 #include "../../../../../cxx_impl/src/window_manager.h"
+#include "../../../../../cxx_impl/src/window_registry.h"
 #endif
 
 // C API headers (available for both C and C++)

packages/cnativeapi/ios/cnativeapi/Sources/cnativeapi/include/cnativeapi.h

@@ -586,6 +586,17 @@ class CNativeApiBindings {
   late final _native_window_get_position = _native_window_get_positionPtr
       .asFunction<native_point_t Function(native_window_t)>();
 
+  void native_window_center(native_window_t window) {
+    return _native_window_center(window);
+  }
+
+  late final _native_window_centerPtr =
+      _lookup<ffi.NativeFunction<ffi.Void Function(native_window_t)>>(
+        'native_window_center',
+      );
+  late final _native_window_center = _native_window_centerPtr
+      .asFunction<void Function(native_window_t)>();
+
   /// Window properties
   void native_window_set_resizable(native_window_t window, bool resizable) {
     return _native_window_set_resizable(window, resizable);
@@ -3823,7 +3834,8 @@ class CNativeApiBindings {
       _native_window_manager_shutdownPtr.asFunction<void Function()>();
 
   /// Set (or clear) the "will show" hook.
-  /// @param callback Function called before window is shown (e.g., makeKeyAndOrderFront: on macOS). NULL to clear.
+  /// @param callback Function called before window is shown (e.g., makeKeyAndOrderFront: on macOS).
+  /// NULL to clear.
   /// @param user_data Opaque pointer passed back to callback.
   void native_window_manager_set_will_show_hook(
     native_window_will_show_callback_t callback,
@@ -3851,7 +3863,8 @@ class CNativeApiBindings {
           >();
 
   /// Set (or clear) the "will hide" hook.
-  /// @param callback Function called before window is hidden (e.g., orderOut: on macOS). NULL to clear.
+  /// @param callback Function called before window is hidden (e.g., orderOut: on macOS). NULL to
+  /// clear.
   /// @param user_data Opaque pointer passed back to callback.
   void native_window_manager_set_will_hide_hook(
     native_window_will_hide_callback_t callback,

packages/cnativeapi/lib/src/bindings_generated.dart

@@ -46,3 +46,4 @@
 #include "../../../../cxx_impl/src/secure_storage.cpp"
 #include "../../../../cxx_impl/src/tray_manager.cpp"
 #include "../../../../cxx_impl/src/window_manager.cpp"
+#include "../../../../cxx_impl/src/window_registry.cpp"

packages/cnativeapi/macos/cnativeapi/Sources/cnativeapi/cnativeapi.mm

@@ -14,6 +14,7 @@
 #include "../../../../../cxx_impl/src/foundation/geometry.h"
 #include "../../../../../cxx_impl/src/foundation/id_allocator.h"
 #include "../../../../../cxx_impl/src/foundation/native_object_provider.h"
+#include "../../../../../cxx_impl/src/foundation/object_registry.h"
 #include "../../../../../cxx_impl/src/image.h"
 #include "../../../../../cxx_impl/src/keyboard_event.h"
 #include "../../../../../cxx_impl/src/keyboard_monitor.h"
@@ -31,6 +32,7 @@
 #include "../../../../../cxx_impl/src/window.h"
 #include "../../../../../cxx_impl/src/window_event.h"
 #include "../../../../../cxx_impl/src/window_manager.h"
+#include "../../../../../cxx_impl/src/window_registry.h"
 #endif
 
 // C API headers (available for both C and C++)

packages/cnativeapi/macos/cnativeapi/Sources/cnativeapi/include/cnativeapi.h

@@ -1,5 +1,6 @@
 import 'dart:ffi' hide Size;
 import 'package:ffi/ffi.dart' as ffi;
+import 'package:nativeapi/src/display_manager.dart';
 import 'package:nativeapi/src/foundation/cnativeapi_bindings_mixin.dart';
 import 'package:nativeapi/src/foundation/geometry.dart';
 import 'package:nativeapi/src/foundation/native_handle_wrapper.dart';
@@ -236,6 +237,25 @@ class Window
     return Offset(nativePoint.x, nativePoint.y);
   }
 
+  /// Centers the window on the primary screen.
+  ///
+  /// This method calculates the center position based on the primary display's
+  /// size and the window's current size, then sets the window position accordingly.
+  void center() {
+    final primaryDisplay = DisplayManager.instance.getPrimary();
+    if (primaryDisplay == null) {
+      return;
+    }
+
+    final screenSize = primaryDisplay.size;
+    final windowSize = size;
+
+    final centerX = (screenSize.width - windowSize.width) / 2;
+    final centerY = (screenSize.height - windowSize.height) / 2;
+
+    setPosition(centerX, centerY);
+  }
+
   // === Window Properties ===
 
   /// Sets whether the window can be resized.