Add smart_gaps inverse_outer command

Add a subcommand for `smart_gaps` that enables outer gaps only
on workspaces with exactly one visible child.
Also add documentation for `smart_gaps toggle`.

include/sway/config.h

@@ -283,6 +283,12 @@ struct side_gaps {
 	int left;
 };
 
+enum smart_gaps_mode {
+	SMART_GAPS_OFF,
+	SMART_GAPS_ON,
+	SMART_GAPS_INVERSE_OUTER,
+};
+
 /**
  * Stores configuration for a workspace, regardless of whether the workspace
  * exists.
@@ -512,7 +518,7 @@ struct sway_config {
 	bool tiling_drag;
 	int tiling_drag_threshold;
 
-	bool smart_gaps;
+	enum smart_gaps_mode smart_gaps;
 	int gaps_inner;
 	struct side_gaps gaps_outer;
 

sway/commands/smart_gaps.c

@@ -15,7 +15,12 @@ struct cmd_results *cmd_smart_gaps(int argc, char **argv) {
 		return error;
 	}
 
-	config->smart_gaps = parse_boolean(argv[0], config->smart_gaps);
+	if (strcmp(argv[0], "inverse_outer") == 0) {
+		config->smart_gaps = SMART_GAPS_INVERSE_OUTER;
+	} else {
+		config->smart_gaps = parse_boolean(argv[0], config->smart_gaps)
+			? SMART_GAPS_ON : SMART_GAPS_OFF;
+	}
 
 	arrange_root();
 

sway/config.c

@@ -266,7 +266,7 @@ static void config_defaults(struct sway_config *config) {
 	config->tiling_drag = true;
 	config->tiling_drag_threshold = 9;
 
-	config->smart_gaps = false;
+	config->smart_gaps = SMART_GAPS_OFF;
 	config->gaps_inner = 0;
 	config->gaps_outer.top = 0;
 	config->gaps_outer.right = 0;

sway/sway.5.scd

@@ -692,9 +692,10 @@ The default colors are:
 	borders will only be enabled if the workspace has more than one visible
 	child and gaps equal to zero.
 
-*smart_gaps* on|off
+*smart_gaps* on|off|toggle|inverse_outer
 	If smart_gaps are _on_ gaps will only be enabled if a workspace has more
-	than one child.
+	than one child. If smart_gaps are _inverse_outer_ outer gaps will only
+	be enabled if a workspace has exactly one child.
 
 *mark* --add|--replace [--toggle] <identifier>
 	Marks are arbitrary labels that can be used to identify certain windows and

sway/tree/workspace.c

@@ -844,24 +844,36 @@ struct sway_container *workspace_insert_tiling(struct sway_workspace *workspace,
 	return con;
 }
 
+bool workspace_has_single_visible_container(struct sway_workspace *ws) {
+	struct sway_seat *seat = input_manager_get_default_seat();
+	struct sway_container *focus =
+		seat_get_focus_inactive_tiling(seat, ws);
+	if (focus && !focus->view) {
+		focus = seat_get_focus_inactive_view(seat, &focus->node);
+	}
+	return (focus && focus->view && view_ancestor_is_only_visible(focus->view));
+}
+
 void workspace_add_gaps(struct sway_workspace *ws) {
-	if (config->smart_gaps) {
-		struct sway_seat *seat = input_manager_get_default_seat();
-		struct sway_container *focus =
-			seat_get_focus_inactive_tiling(seat, ws);
-		if (focus && !focus->view) {
-			focus = seat_get_focus_inactive_view(seat, &focus->node);
-		}
-		if (focus && focus->view && view_ancestor_is_only_visible(focus->view)) {
-			ws->current_gaps.top = 0;
-			ws->current_gaps.right = 0;
-			ws->current_gaps.bottom = 0;
-			ws->current_gaps.left = 0;
-			return;
-		}
+	if (config->smart_gaps == SMART_GAPS_ON
+			&& workspace_has_single_visible_container(ws)) {
+		ws->current_gaps.top = 0;
+		ws->current_gaps.right = 0;
+		ws->current_gaps.bottom = 0;
+		ws->current_gaps.left = 0;
+		return;
+	}
+
+	if (config->smart_gaps == SMART_GAPS_INVERSE_OUTER
+			&& !workspace_has_single_visible_container(ws)) {
+		ws->current_gaps.top = 0;
+		ws->current_gaps.right = 0;
+		ws->current_gaps.bottom = 0;
+		ws->current_gaps.left = 0;
+	} else {
+		ws->current_gaps = ws->gaps_outer;
 	}
 
-	ws->current_gaps = ws->gaps_outer;
 	// Add inner gaps and make sure we don't turn out negative
 	ws->current_gaps.top = fmax(0, ws->current_gaps.top + ws->gaps_inner);
 	ws->current_gaps.right = fmax(0, ws->current_gaps.right + ws->gaps_inner);