From f3dfc4ad4e8e103802e4f791ea2215a286812668 Mon Sep 17 00:00:00 2001
From: Susko3 <Susko3@protonmail.com>
Date: Mon, 22 Apr 2024 21:06:27 +0200
Subject: [PATCH] Bring back borderless mode for macOS and Linux

This partially reverts 0e78180d07a828fdad8655ea34efa89ff4744678
---
 osu.Framework/Platform/SDL/SDL3Extensions.cs   |  5 +++--
 osu.Framework/Platform/SDL3Window_Windowing.cs | 18 ++++++++++++------
 2 files changed, 15 insertions(+), 8 deletions(-)

diff --git a/osu.Framework/Platform/SDL/SDL3Extensions.cs b/osu.Framework/Platform/SDL/SDL3Extensions.cs
index abf451ce40..3c75634ba3 100644
--- a/osu.Framework/Platform/SDL/SDL3Extensions.cs
+++ b/osu.Framework/Platform/SDL/SDL3Extensions.cs
@@ -859,8 +859,9 @@ public static SDL_Scancode ToScancode(this InputKey inputKey)
             }
         }
 
-        public static WindowState ToWindowState(this SDL_WindowFlags windowFlags)
+        public static WindowState ToWindowState(this SDL_WindowFlags windowFlags, bool isFullscreenBorderless)
         {
+            // for windows
             if (windowFlags.HasFlagFast(SDL_WindowFlags.SDL_WINDOW_BORDERLESS))
                 return WindowState.FullscreenBorderless;
 
@@ -868,7 +869,7 @@ public static WindowState ToWindowState(this SDL_WindowFlags windowFlags)
                 return WindowState.Minimised;
 
             if (windowFlags.HasFlagFast(SDL_WindowFlags.SDL_WINDOW_FULLSCREEN))
-                return WindowState.Fullscreen;
+                return isFullscreenBorderless ? WindowState.FullscreenBorderless : WindowState.Fullscreen;
 
             if (windowFlags.HasFlagFast(SDL_WindowFlags.SDL_WINDOW_MAXIMIZED))
                 return WindowState.Maximised;
diff --git a/osu.Framework/Platform/SDL3Window_Windowing.cs b/osu.Framework/Platform/SDL3Window_Windowing.cs
index 12150fda19..ad31c39f6e 100644
--- a/osu.Framework/Platform/SDL3Window_Windowing.cs
+++ b/osu.Framework/Platform/SDL3Window_Windowing.cs
@@ -146,10 +146,7 @@ public virtual IEnumerable<WindowMode> SupportedWindowModes
                 if (RuntimeInfo.IsMobile)
                     return new[] { Configuration.WindowMode.Fullscreen };
 
-                if (RuntimeInfo.OS == RuntimeInfo.Platform.Windows)
-                    return Enum.GetValues<WindowMode>();
-
-                return new[] { Configuration.WindowMode.Windowed, Configuration.WindowMode.Fullscreen };
+                return Enum.GetValues<WindowMode>();
             }
         }
 
@@ -577,7 +574,7 @@ private unsafe void updateAndFetchWindowSpecifics()
             }
             else
             {
-                windowState = SDL3.SDL_GetWindowFlags(SDLWindowHandle).ToWindowState();
+                windowState = SDL3.SDL_GetWindowFlags(SDLWindowHandle).ToWindowState(SDL3.SDL_GetWindowFullscreenMode(SDLWindowHandle) == null);
             }
 
             if (windowState != stateBefore)
@@ -799,7 +796,16 @@ private void storeWindowSizeToConfig()
         /// <returns>
         /// The size of the borderless window's draw area.
         /// </returns>
-        protected virtual Size SetBorderless(Display display) => throw new PlatformNotSupportedException();
+        protected virtual unsafe Size SetBorderless(Display display)
+        {
+            ensureWindowOnDisplay(display);
+
+            // this is a generally sane method of handling borderless, and works well on macOS and linux.
+            SDL3.SDL_SetWindowFullscreenMode(SDLWindowHandle, null);
+            SDL3.SDL_SetWindowFullscreen(SDLWindowHandle, SDL_bool.SDL_TRUE);
+
+            return display.Bounds.Size;
+        }
 
         #endregion