Use XCB to check if an application is fullscreen

man/compton.1.asciidoc

@@ -256,6 +256,9 @@ May also be one of the predefined kernels: `3x3box` (default), `5x5box`, `7x7box
 *--benchmark-wid* 'WINDOW_ID'::
 	Specify window ID to repaint in benchmark mode. If omitted or is 0, the whole screen is repainted.
 
+*--no-ewmh-fullscreen*::
+	Do not use EWMH to detect fullscreen windows. Reverts to checking if a window is fullscreen based only on its size and coordinates.
+
 FORMAT OF CONDITIONS
 --------------------
 Some options accept a condition string to match certain windows. A condition string is formed by one or more conditions, joined by logical operators.

src/atom.h

@@ -34,7 +34,9 @@
 	_NET_WM_WINDOW_TYPE_TOOLTIP, \
 	_NET_WM_WINDOW_TYPE_NOTIFICATION, \
 	_NET_WM_WINDOW_TYPE_COMBO, \
-	_NET_WM_WINDOW_TYPE_DND
+	_NET_WM_WINDOW_TYPE_DND, \
+	_NET_WM_STATE, \
+	_NET_WM_STATE_FULLSCREEN
 
 #define ATOM_DEF(x) xcb_atom_t a##x
 

src/config.c

@@ -554,6 +554,7 @@ char *parse_config(options_t *opt, const char *config_file, bool *shadow_enable,
 	    .focus_blacklist = NULL,
 	    .detect_transient = false,
 	    .detect_client_leader = false,
+	    .no_ewmh_fullscreen = false,
 
 	    .track_wdata = false,
 	    .track_leader = false,

src/config.h

@@ -224,6 +224,9 @@ typedef struct options {
 	bool track_wdata;
 	/// Whether compton needs to track window leaders.
 	bool track_leader;
+
+	// Don't use EWMH to detect fullscreen applications
+	bool no_ewmh_fullscreen;
 } options_t;
 
 extern const char *const BACKEND_STRS[NUM_BKEND + 1];

src/config_libconfig.c

@@ -355,6 +355,8 @@ char *parse_config_libconfig(options_t *opt, const char *config_file, bool *shad
 	lcfg_lookup_bool(&cfg, "detect-transient", &opt->detect_transient);
 	// --detect-client-leader
 	lcfg_lookup_bool(&cfg, "detect-client-leader", &opt->detect_client_leader);
+	// --no-ewmh-fullscreen
+	lcfg_lookup_bool(&cfg, "no-ewmh-fullscreen", &opt->no_ewmh_fullscreen);
 	// --shadow-exclude
 	parse_cfg_condlst(&cfg, &opt->shadow_blacklist, "shadow-exclude");
 	// --fade-exclude

src/options.c

@@ -315,7 +315,11 @@ static void usage(int ret) {
 	    "\n"
 	    "--debug-mode\n"
 	    "  Render into a separate window, and don't take over the screen. Useful\n"
-	    "  when you want to attach a debugger to compton\n";
+	    "  when you want to attach a debugger to compton\n"
+	    "\n"
+	    "--no-ewmh-fullscreen\n"
+	    "  Do not use EWMH to detect fullscreen windows. Reverts to checking\n"
+	    "  if a window is fullscreen based only on its size and coordinates.\n";
 	FILE *f = (ret ? stderr : stdout);
 	fputs(usage_text, f);
 #undef WARNING_DISABLED
@@ -412,6 +416,7 @@ static const struct option longopts[] = {
     {"monitor-repaint", no_argument, NULL, 800},
     {"diagnostics", no_argument, NULL, 801},
     {"debug-mode", no_argument, NULL, 802},
+    {"no-ewmh-fullscreen", no_argument, NULL, 803},
     // Must terminate with a NULL entry
     {NULL, 0, NULL, 0},
 };
@@ -784,6 +789,7 @@ void get_cfg(options_t *opt, int argc, char *const *argv, bool shadow_enable,
 		P_CASEBOOL(800, monitor_repaint);
 		case 801: opt->print_diagnostics = true; break;
 		P_CASEBOOL(802, debug_mode);
+		P_CASEBOOL(803, no_ewmh_fullscreen);
 		default: usage(1); break;
 #undef P_CASEBOOL
 		}

src/win.c

@@ -2151,12 +2151,36 @@ static inline bool rect_is_fullscreen(const session_t *ps, int x, int y, int wid
 	return (x <= 0 && y <= 0 && (x + wid) >= ps->root_width && (y + hei) >= ps->root_height);
 }
 
+/**
+ * Check if a window is fulscreen using EWMH
+ */
+static inline bool win_is_fullscreen_xcb(xcb_connection_t *c, const struct atom *a, const xcb_window_t w) {
+	xcb_get_property_cookie_t prop = xcb_get_property(c, 0, w, a->a_NET_WM_STATE, XCB_ATOM_ATOM, 0, 12);
+	xcb_get_property_reply_t *reply = xcb_get_property_reply(c, prop, NULL);
+	if(!reply)
+		return false;
+
+	if(reply->length) {
+		xcb_atom_t *val = xcb_get_property_value(reply);
+		for(uint32_t i = 0; i < reply->length; i++) {
+			if(val[i] != a->a_NET_WM_STATE_FULLSCREEN)
+				continue;
+			free(reply);
+			return true;
+		}
+	}
+	free(reply);
+	return false;
+}
+
 /**
  * Check if a window is a fullscreen window.
  *
  * It's not using w->border_size for performance measures.
  */
 bool win_is_fullscreen(const session_t *ps, const struct managed_win *w) {
+	if(!ps->o.no_ewmh_fullscreen && win_is_fullscreen_xcb(ps->c, ps->atoms, w->client_win))
+		return true;
 	return rect_is_fullscreen(ps, w->g.x, w->g.y, w->widthb, w->heightb) &&
 	       (!w->bounding_shaped || w->rounded_corners);
 }