Implement very basic grab pointer

This is definitely not correct with child windows but works with single
window apps (minecraft)

xbanan/Base.cpp

@@ -28,6 +28,8 @@ CARD16 g_keymask { 0 };
 CARD16 g_butmask { 0 };
 WINDOW g_focus_window { None };
 
+static WINDOW s_pointer_grab_wid = None;
+
 static const char* s_opcode_to_name[] {
 	[0] = "none",
 	[X_CreateWindow] = "X_CreateWindow",
@@ -1852,13 +1854,37 @@ BAN::ErrorOr<void> handle_packet(Client& client_info, BAN::ConstByteSpan packet)
 			dprintln("  cursor:       {}", request.cursor);
 			dprintln("  time:         {}", request.time);
 
-			xGrabPointerReply reply {
-				.type = X_Reply,
-				.status = Success,
-				.sequenceNumber = client_info.sequence,
-				.length = 0,
-			};
-			TRY(encode(client_info.output_buffer, reply));
+			auto& window = TRY_REF(get_window(client_info, request.grabWindow, X_GrabPointer));
+
+			if (s_pointer_grab_wid != None && !g_objects.contains(s_pointer_grab_wid))
+				s_pointer_grab_wid = None;
+
+			if (s_pointer_grab_wid == None)
+			{
+				xGrabPointerReply reply {
+					.type = X_Reply,
+					.status = Success,
+					.sequenceNumber = client_info.sequence,
+					.length = 0,
+				};
+				TRY(encode(client_info.output_buffer, reply));
+
+				if (g_platform_ops.set_pointer_grab)
+					if (auto* platform_window = get_platform_window(window))
+						g_platform_ops.set_pointer_grab(platform_window, true);
+
+				s_pointer_grab_wid = request.grabWindow;
+			}
+			else
+			{
+				xGrabPointerReply reply {
+					.type = X_Reply,
+					.status = AlreadyGrabbed,
+					.sequenceNumber = client_info.sequence,
+					.length = 0,
+				};
+				TRY(encode(client_info.output_buffer, reply));
+			}
 
 			break;
 		}
@@ -1869,6 +1895,16 @@ BAN::ErrorOr<void> handle_packet(Client& client_info, BAN::ConstByteSpan packet)
 			dprintln("UngrabPointer");
 			dprintln("  time: {}", time);
 
+			if (s_pointer_grab_wid == None)
+				break;
+
+			auto it = g_objects.find(s_pointer_grab_wid);
+			if (it != g_objects.end() && g_platform_ops.set_pointer_grab)
+				if (auto* platform_window = get_platform_window(it->value->object.get<Object::Window>()))
+					g_platform_ops.set_pointer_grab(platform_window, false);
+
+			s_pointer_grab_wid = None;
+
 			break;
 		}
 		case X_GrabKeyboard:

xbanan/Platform.h

@@ -63,6 +63,8 @@ struct PlatformOps
 	void (*warp_pointer)(int32_t x, int32_t y, bool relative);
 	/* Get global position of the pointer */
 	void (*query_pointer)(int32_t* x, int32_t* y);
+	/* Grab pointer events on window */
+	void (*set_pointer_grab)(PlatformWindow*, bool grabbed);
 	/* Create a system cursor */
 	BAN::ErrorOr<BAN::UniqPtr<PlatformCursor>> (*create_system_cursor)(SystemCursorType);
 	/* Create cursor from custom bitmap */

xbanan/SDL3/sdl3.cpp

@@ -356,6 +356,12 @@ static void sdl3_query_pointer(int32_t* x, int32_t* y)
 	*y = cy;
 }
 
+static void sdl3_set_pointer_grab(PlatformWindow* window, bool grabbed)
+{
+	auto& sdl_window = *static_cast<SDLWindow*>(window);
+	SDL_SetWindowMouseGrab(sdl_window.window, grabbed);
+}
+
 static BAN::ErrorOr<BAN::UniqPtr<PlatformCursor>> sdl3_create_system_cursor(SystemCursorType type)
 {
 	static constexpr SDL_SystemCursor cursor_type_map[] {
@@ -437,6 +443,7 @@ PlatformOps g_platform_ops = {
 	.request_fullscreen   = sdl3_request_fullscreen,
 	.warp_pointer         = sdl3_warp_pointer,
 	.query_pointer        = sdl3_query_pointer,
+	.set_pointer_grab     = sdl3_set_pointer_grab,
 	.create_system_cursor = sdl3_create_system_cursor,
 	.create_bitmap_cursor = sdl3_create_bitmap_cursor,
 	.set_cursor           = sdl3_set_cursor,

xbanan/banan-os/banan-os.cpp

@@ -160,6 +160,12 @@ static void bananos_query_pointer(int32_t* x, int32_t* y)
 	(void)y;
 }
 
+static void bananos_set_pointer_grab(PlatformWindow* window, bool grabbed)
+{
+	(void)window;
+	(void)grabbed;
+}
+
 static BAN::ErrorOr<BAN::UniqPtr<PlatformCursor>> bananos_create_system_cursor(SystemCursorType type)
 {
 	(void)type;
@@ -205,6 +211,7 @@ PlatformOps g_platform_ops = {
 	.request_fullscreen   = bananos_request_fullscreen,
 	.warp_pointer         = bananos_warp_pointer,
 	.query_pointer        = nullptr, /* bananos_query_pointer */
+	.set_pointer_grab     = bananos_set_pointer_grab,
 	.create_system_cursor = bananos_create_system_cursor,
 	.create_bitmap_cursor = bananos_create_bitmap_cursor,
 	.set_cursor           = bananos_set_cursor,