win: remember calculated fullscreen state for window

Signed-off-by: Yuxuan Shui <yshuiv7@gmail.com>

src/c2.c

@@ -1380,9 +1380,7 @@ static inline void c2_match_once_leaf(session_t *ps, const struct managed_win *w
 			case C2_L_PWIDTHB: predef_target = w->widthb; break;
 			case C2_L_PHEIGHTB: predef_target = w->heightb; break;
 			case C2_L_PBDW: predef_target = w->g.border_width; break;
-			case C2_L_PFULLSCREEN:
-				predef_target = win_is_fullscreen(ps, w);
-				break;
+			case C2_L_PFULLSCREEN: predef_target = w->is_fullscreen; break;
 			case C2_L_POVREDIR: predef_target = w->a.override_redirect; break;
 			case C2_L_PARGB: predef_target = win_has_alpha(w); break;
 			case C2_L_PFOCUSED:

src/picom.c

@@ -791,6 +791,8 @@ err:
 
 /// Handle configure event of the root window
 static void configure_root(session_t *ps) {
+	// TODO(yshui) re-initializing backend should be done outside of the
+	// critical section. Probably set a flag and do it in draw_callback_impl.
 	auto r = XCB_AWAIT(xcb_get_geometry, ps->c.c, ps->c.screen_info->root);
 	if (!r) {
 		log_fatal("Failed to fetch root geometry");
@@ -830,6 +832,13 @@ static void configure_root(session_t *ps) {
 		top_w->reg_ignore_valid = false;
 	}
 
+	// Whether a window is fullscreen depends on the new screen
+	// size. So we need to refresh the fullscreen state of all
+	// windows.
+	win_stack_foreach_managed(w, &ps->window_stack) {
+		win_update_is_fullscreen(ps, w);
+	}
+
 	if (ps->redirected) {
 		for (int i = 0; i < ps->ndamage; i++) {
 			pixman_region32_clear(&ps->damage_ring[i]);
@@ -1072,7 +1081,7 @@ static bool paint_preprocess(session_t *ps, bool *fade_running, bool *animation,
 		// is not correctly set.
 		if (ps->o.unredir_if_possible && is_highest) {
 			if (w->mode == WMODE_SOLID && !ps->o.force_win_blend &&
-			    win_is_fullscreen(ps, w) && !w->unredir_if_possible_excluded) {
+			    w->is_fullscreen && !w->unredir_if_possible_excluded) {
 				unredir_possible = true;
 			}
 		}

src/win.c

@@ -520,6 +520,9 @@ void win_process_update_flags(session_t *ps, struct managed_win *w) {
 		// Update window geometry
 		w->g = w->pending_g;
 
+		// Whether a window is fullscreen changes based on its geometry
+		win_update_is_fullscreen(ps, w);
+
 		if (win_check_flags_all(w, WIN_FLAGS_SIZE_STALE)) {
 			win_on_win_size_change(ps, w);
 			win_update_bounding_shape(ps, w);
@@ -1187,7 +1190,7 @@ static void win_determine_rounded_corners(session_t *ps, struct managed_win *w)
 
 	// Don't round full screen windows & excluded windows,
 	// unless we find a corner override in corner_radius_rules
-	if (!radius_override && ((w && win_is_fullscreen(ps, w)) ||
+	if (!radius_override && ((w && w->is_fullscreen) ||
 	                         c2_match(ps, w, ps->o.rounded_corners_blacklist, NULL))) {
 		w->corner_radius = 0;
 		log_debug("Not rounding corners for window %#010x", w->base.id);
@@ -1254,9 +1257,10 @@ void win_update_opacity_rule(session_t *ps, struct managed_win *w) {
  */
 void win_on_factor_change(session_t *ps, struct managed_win *w) {
 	log_debug("Window %#010x (%s) factor change", w->base.id, w->name);
-	// Focus needs to be updated first, as other rules might depend on the
-	// focused state of the window
+	// Focus and is_fullscreen needs to be updated first, as other rules might depend
+	// on the focused state of the window
 	win_update_focused(ps, w);
+	win_update_is_fullscreen(ps, w);
 
 	win_determine_shadow(ps, w);
 	win_determine_clip_shadow_above(ps, w);
@@ -2746,13 +2750,6 @@ struct managed_win *find_managed_window_or_parent(session_t *ps, xcb_window_t wi
 	return (struct managed_win *)w;
 }
 
-/**
- * Check if a rectangle includes the whole screen.
- */
-static inline bool rect_is_fullscreen(const session_t *ps, int x, int y, int wid, int hei) {
-	return (x <= 0 && y <= 0 && (x + wid) >= ps->root_width && (y + hei) >= ps->root_height);
-}
-
 /// Set flags on a window. Some sanity checks are performed
 void win_set_flags(struct managed_win *w, uint64_t flags) {
 	log_debug("Set flags %" PRIu64 " to window %#010x (%s)", flags, w->base.id, w->name);
@@ -2837,12 +2834,15 @@ bool win_check_flags_all(struct managed_win *w, uint64_t flags) {
  *
  * It's not using w->border_size for performance measures.
  */
-bool win_is_fullscreen(const session_t *ps, const struct managed_win *w) {
+void win_update_is_fullscreen(const session_t *ps, struct managed_win *w) {
 	if (!ps->o.no_ewmh_fullscreen && w->is_ewmh_fullscreen) {
-		return true;
+		w->is_fullscreen = true;
+		return;
 	}
-	return rect_is_fullscreen(ps, w->g.x, w->g.y, w->widthb, w->heightb) &&
-	       (!w->bounding_shaped || w->rounded_corners);
+	w->is_fullscreen = w->g.x <= 0 && w->g.y <= 0 &&
+	                   (w->g.x + w->widthb) >= ps->root_width &&
+	                   (w->g.y + w->heightb) >= ps->root_height &&
+	                   (!w->bounding_shaped || w->rounded_corners);
 }
 
 /**

src/win.h

@@ -201,6 +201,10 @@ struct managed_win {
 	char *role;
 	/// Whether the window sets the EWMH fullscreen property.
 	bool is_ewmh_fullscreen;
+	/// Whether the window should be considered fullscreen. Based on
+	/// `is_ewmh_fullscreen`, or the windows spatial relation with the
+	/// root window. Which one is used is determined by user configuration.
+	bool is_fullscreen;
 
 	// Opacity-related members
 	/// Current window opacity.
@@ -351,6 +355,8 @@ void win_update_monitor(struct x_monitors *monitors, struct managed_win *mw);
  */
 // XXX was win_border_size
 void win_update_bounding_shape(session_t *ps, struct managed_win *w);
+/// Recheck if a window is fullscreen
+void win_update_is_fullscreen(const session_t *ps, struct managed_win *w);
 /**
  * Check if a window has BYPASS_COMPOSITOR property set
  */
@@ -426,13 +432,6 @@ struct managed_win *find_toplevel(session_t *ps, xcb_window_t id);
  */
 struct managed_win *find_managed_window_or_parent(session_t *ps, xcb_window_t wid);
 
-/**
- * Check if a window is a fullscreen window.
- *
- * It's not using w->border_size for performance measures.
- */
-bool attr_pure win_is_fullscreen(const session_t *ps, const struct managed_win *w);
-
 /**
  * Check if a window is focused, without using any focus rules or forced focus settings
  */