Added OS::center_window to center the window precisely on desktop platforms

core/bind/core_bind.cpp

@@ -261,6 +261,10 @@ Size2 _OS::get_window_size() const {
 	return OS::get_singleton()->get_window_size();
 }
 
+Size2 _OS::get_real_window_size() const {
+	return OS::get_singleton()->get_real_window_size();
+}
+
 void _OS::set_window_size(const Size2 &p_size) {
 	OS::get_singleton()->set_window_size(p_size);
 }
@@ -935,6 +939,11 @@ void _OS::request_attention() {
 	OS::get_singleton()->request_attention();
 }
 
+void _OS::center_window() {
+
+	OS::get_singleton()->center_window();
+}
+
 bool _OS::is_debug_build() const {
 
 #ifdef DEBUG_ENABLED
@@ -1032,6 +1041,8 @@ void _OS::_bind_methods() {
 	ObjectTypeDB::bind_method(_MD("set_window_maximized", "enabled"), &_OS::set_window_maximized);
 	ObjectTypeDB::bind_method(_MD("is_window_maximized"), &_OS::is_window_maximized);
 	ObjectTypeDB::bind_method(_MD("request_attention"), &_OS::request_attention);
+	ObjectTypeDB::bind_method(_MD("get_real_window_size"), &_OS::get_real_window_size);
+	ObjectTypeDB::bind_method(_MD("center_window"), &_OS::center_window);
 
 	ObjectTypeDB::bind_method(_MD("set_borderless_window", "borderless"), &_OS::set_borderless_window);
 	ObjectTypeDB::bind_method(_MD("get_borderless_window"), &_OS::get_borderless_window);

core/bind/core_bind.h

@@ -142,6 +142,7 @@ public:
 	virtual Point2 get_window_position() const;
 	virtual void set_window_position(const Point2 &p_position);
 	virtual Size2 get_window_size() const;
+	virtual Size2 get_real_window_size() const;
 	virtual void set_window_size(const Size2 &p_size);
 	virtual void set_window_fullscreen(bool p_enabled);
 	virtual bool is_window_fullscreen() const;
@@ -152,6 +153,7 @@ public:
 	virtual void set_window_maximized(bool p_enabled);
 	virtual bool is_window_maximized() const;
 	virtual void request_attention();
+	virtual void center_window();
 
 	virtual void set_borderless_window(bool p_borderless);
 	virtual bool get_borderless_window() const;

core/os/os.cpp

@@ -546,6 +546,17 @@ Dictionary OS::get_engine_version() const {
 	return dict;
 }
 
+void OS::center_window() {
+
+	if (is_window_fullscreen()) return;
+
+	Size2 scr = get_screen_size(get_current_screen());
+	Size2 wnd = get_real_window_size();
+	int x = scr.width / 2 - wnd.width / 2;
+	int y = scr.height / 2 - wnd.height / 2;
+	set_window_position(Vector2(x, y));
+}
+
 OS::OS() {
 	last_error = NULL;
 	frames_drawn = 0;

core/os/os.h

@@ -168,6 +168,7 @@ public:
 	virtual Point2 get_window_position() const { return Vector2(); }
 	virtual void set_window_position(const Point2 &p_position) {}
 	virtual Size2 get_window_size() const = 0;
+	virtual Size2 get_real_window_size() const { return get_window_size(); }
 	virtual void set_window_size(const Size2 p_size) {}
 	virtual void set_window_fullscreen(bool p_enabled) {}
 	virtual bool is_window_fullscreen() const { return true; }
@@ -178,6 +179,7 @@ public:
 	virtual void set_window_maximized(bool p_enabled) {}
 	virtual bool is_window_maximized() const { return true; }
 	virtual void request_attention() {}
+	virtual void center_window();
 
 	virtual void set_borderless_window(int p_borderless) {}
 	virtual bool get_borderless_window() { return 0; }

platform/osx/os_osx.h

@@ -159,6 +159,7 @@ public:
 	virtual void set_window_title(const String &p_title);
 
 	virtual Size2 get_window_size() const;
+	virtual Size2 get_real_window_size() const;
 
 	virtual void set_icon(const Image &p_icon);
 

platform/osx/os_osx.mm

@@ -1549,6 +1549,12 @@ Size2 OS_OSX::get_window_size() const {
 	return window_size;
 };
 
+Size2 OS_OSX::get_real_window_size() const {
+
+	NSRect frame = [window_object frame];
+	return Size2(frame.size.width, frame.size.height);
+}
+
 void OS_OSX::set_window_size(const Size2 p_size) {
 
 	Size2 size = p_size;

platform/windows/os_windows.cpp

@@ -1486,6 +1486,12 @@ Size2 OS_Windows::get_window_size() const {
 	GetClientRect(hWnd, &r);
 	return Vector2(r.right - r.left, r.bottom - r.top);
 }
+Size2 OS_Windows::get_real_window_size() const {
+
+	RECT r;
+	GetWindowRect(hWnd, &r);
+	return Vector2(r.right - r.left, r.bottom - r.top);
+}
 void OS_Windows::set_window_size(const Size2 p_size) {
 
 	video_mode.width = p_size.width;

platform/windows/os_windows.h

@@ -211,6 +211,7 @@ public:
 	virtual Point2 get_window_position() const;
 	virtual void set_window_position(const Point2 &p_position);
 	virtual Size2 get_window_size() const;
+	virtual Size2 get_real_window_size() const;
 	virtual void set_window_size(const Size2 p_size);
 	virtual void set_window_fullscreen(bool p_enabled);
 	virtual bool is_window_fullscreen() const;

platform/x11/os_x11.cpp

@@ -801,6 +801,26 @@ Size2 OS_X11::get_window_size() const {
 	return Size2i(current_videomode.width, current_videomode.height);
 }
 
+Size2 OS_X11::get_real_window_size() const {
+	XWindowAttributes xwa;
+	XSync(x11_display, False);
+	XGetWindowAttributes(x11_display, x11_window, &xwa);
+	int w = xwa.width;
+	int h = xwa.height;
+	Atom prop = XInternAtom(x11_display, "_NET_FRAME_EXTENTS", True);
+	Atom type;
+	int format;
+	unsigned long len;
+	unsigned long remaining;
+	unsigned char *data = NULL;
+	if (XGetWindowProperty(x11_display, x11_window, prop, 0, 4, False, AnyPropertyType, &type, &format, &len, &remaining, &data) == Success) {
+		long *extents = (long*) data;
+		w += extents[0] + extents[1]; // left, right
+		h += extents[2] + extents[3]; // top, bottom
+	}
+	return Size2(w, h);
+}
+
 void OS_X11::set_window_size(const Size2 p_size) {
 	// If window resizable is disabled we need to update the attributes first
 	if (is_window_resizable() == false) {

platform/x11/os_x11.h

@@ -246,6 +246,7 @@ public:
 	virtual Point2 get_window_position() const;
 	virtual void set_window_position(const Point2 &p_position);
 	virtual Size2 get_window_size() const;
+	virtual Size2 get_real_window_size() const;
 	virtual void set_window_size(const Size2 p_size);
 	virtual void set_window_fullscreen(bool p_enabled);
 	virtual bool is_window_fullscreen() const;