[macos] Implement getTitleBarHeight methods #34

Author: lijy91

macos/Classes/WindowManager.swift

@@ -333,6 +333,12 @@ public class WindowManager: NSObject, NSWindowDelegate {
         mainWindow.standardWindowButton(.zoomButton)?.isHidden = !windowButtonVisibility
     }
 
+    public func getTitleBarHeight() -> Int {
+        let frame = mainWindow.frame;
+        let windowHeight: CGFloat = mainWindow.frame.height
+        return Int(windowHeight - mainWindow.contentRect(forFrameRect: frame).height)
+    }
+    
     public func setSkipTaskbar(_ args: [String: Any]) {
         let isSkipTaskbar: Bool = args["isSkipTaskbar"] as! Bool
         NSApplication.shared.setActivationPolicy(isSkipTaskbar ? .accessory : .regular)
@@ -342,7 +348,7 @@ public class WindowManager: NSObject, NSWindowDelegate {
         let progress: CGFloat = CGFloat(truncating: args["progress"] as! NSNumber)
 
         let dockTile: NSDockTile = NSApp.dockTile;
-    
+        
         let firstTime = dockTile.contentView == nil || dockTile.contentView?.subviews.count == 0
 
         if (firstTime) {

macos/Classes/WindowManagerPlugin.swift

@@ -176,6 +176,9 @@ public class WindowManagerPlugin: NSObject, FlutterPlugin {
             windowManager.setTitleBarStyle(args)
             result(true)
             break
+        case "getTitleBarHeight":
+            result(windowManager.getTitleBarHeight())
+            break
         case "setSkipTaskbar":
             windowManager.setSkipTaskbar(args)
             result(true)