[macos] Optimize sub-window feature

Author: lijy91

example/lib/pages/home.dart

@@ -447,6 +447,16 @@ class _HomePageState extends State<HomePage> with WindowListener {
                 setState(() {});
               },
             ),
+            PreferenceListItem(
+              title: Text('createSubWindow'),
+              onTap: () async {
+                SubWindow subWindow = await SubWindow.create(
+                  size: Size(800, 600),
+                  center: true,
+                  title: 'title',
+                );
+              },
+            ),
           ],
         ),
       ],

example/macos/Podfile.lock

@@ -1,6 +1,6 @@
 PODS:
   - FlutterMacOS (1.0.0)
-  - window_manager (0.1.0):
+  - window_manager (0.1.2):
     - FlutterMacOS
 
 DEPENDENCIES:
@@ -15,7 +15,7 @@ EXTERNAL SOURCES:
 
 SPEC CHECKSUMS:
   FlutterMacOS: 57701585bf7de1b3fc2bb61f6378d73bbdea8424
-  window_manager: db713621c322d52e96064336a4ba2b7e4e30c94f
+  window_manager: 8c227608c115dbd132510c023d3644274aaec8a8
 
 PODFILE CHECKSUM: 6eac6b3292e5142cfc23bdeb71848a40ec51c14c
 

example/macos/Runner/MainFlutterWindow.swift

@@ -11,6 +11,8 @@ class MainFlutterWindow: NSWindow {
 
         RegisterGeneratedPlugins(registry: flutterViewController)
 
+        WindowManagerPlugin.RegisterGeneratedPlugins = RegisterGeneratedPlugins
+        
         super.awakeFromNib()
     }
 

lib/src/sub_window.dart

@@ -0,0 +1,21 @@
+import 'dart:ui';
+
+import 'window_manager.dart';
+
+class SubWindow {
+  static Future<SubWindow> create({
+    Size? size,
+    Offset? position,
+    bool center = true,
+    required String title,
+  }) async {
+    SubWindow subWindow = SubWindow();
+    windowManager.createSubWindow(
+      size: size,
+      position: position,
+      center: center,
+      title: title,
+    );
+    return subWindow;
+  }
+}

lib/src/window_manager.dart

@@ -358,17 +358,19 @@ class WindowManager {
   }
 
   Future<void> createSubWindow({
+    Size? size,
+    Offset? position,
+    bool center = true,
     required String title,
-    required Offset position,
-    required Size size,
   }) async {
     final Map<String, dynamic> arguments = {
+      'width': size?.width,
+      'height': size?.height,
+      'x': position?.dx,
+      'y': position?.dy,
+      'center': center,
       'title': title,
-      'x': position.dx,
-      'y': position.dy,
-      'width': size.width,
-      'height': size.height,
-    };
+    }..removeWhere((key, value) => value == null);
     await _channel.invokeMethod('createSubWindow', arguments);
   }
 }

lib/window_manager.dart

@@ -1,3 +1,4 @@
 export 'src/drag_to_move_area.dart';
+export 'src/sub_window.dart';
 export 'src/window_listener.dart';
 export 'src/window_manager.dart';

macos/Classes/SubWindow.swift

@@ -8,5 +8,4 @@ public class SubWindow: NSWindow {
 
         super.awakeFromNib()
     }
-    
 }

macos/Classes/WindowManager.swift

@@ -361,16 +361,24 @@ public class WindowManager: NSObject, NSWindowDelegate {
     }
 
     public func createSubWindow(_ args: [String: Any]) {
-        let title: String = args["title"] as! String
+        let visibleFrame = NSScreen.main!.visibleFrame
 
         var frameRect: NSRect = NSRect.zero
+        if (args["width"] != nil && args["width"] != nil) {
+            frameRect.size.width = CGFloat(args["width"] as! Float)
+            frameRect.size.height = CGFloat(args["height"] as! Float)
+        }
         if (args["x"] != nil && args["y"] != nil) {
             frameRect.topLeft.x = CGFloat(args["x"] as! Float)
             frameRect.topLeft.y = CGFloat(args["y"] as! Float)
         }
-        if (args["width"] != nil && args["width"] != nil) {
-            frameRect.size.width = CGFloat(args["width"] as! Float)
-            frameRect.size.height = CGFloat(args["height"] as! Float)
+        
+        let center: Bool = args["center"] as! Bool
+        let title: String = args["title"] as! String
+        
+        if (center) {
+            frameRect.origin.x = (visibleFrame.width / 2) - (frameRect.size.width / 2)
+            frameRect.origin.y = (visibleFrame.height / 2) + (frameRect.size.height / 2)
         }
 
         let flutterViewController = FlutterViewController.init()