implement transition rules

src/config_libconfig.c

@@ -349,6 +349,37 @@ timing_function parse_timing_function(const char *timing_name) {
 	return NULL;
 }
 
+static inline void parse_cfg_condlst_trns(options_t *opt, const config_t *pcfg, const char *name) {
+	config_setting_t *setting = config_lookup(pcfg, name);
+	if (setting) {
+		int length = config_setting_length(setting);
+
+		for (int i = 0; i < length; i++) {
+			const char *elem = config_setting_get_string_elem(setting, i);
+
+			char rule[512];
+			unsigned long elem_index = 0;
+
+			for (int rule_index = 0; elem_index < strlen(elem); elem_index++) {
+				char character = elem[elem_index];
+				if (character == ':') {
+					rule[rule_index] = '\0';
+					break;
+				}
+
+
+				if (!isspace(character)) {
+					rule[rule_index] = character;
+					rule_index++;
+				}
+			}
+
+			int *direction = (int*) parse_transition_direction(rule);
+			c2_parse(&opt->transition_rules, &elem[elem_index + 1], direction);
+		}
+	}
+}
+
 /**
  * Parse a configuration file from default location.
  *
@@ -740,6 +771,8 @@ char *parse_config_libconfig(options_t *opt, const char *config_file, bool *shad
 					opt->transition_timing_function = res;
 				}
 			}
+
+			parse_cfg_condlst_trns(opt, &cfg, "transition-rule");
 		}
 	}
 

src/picom.c

@@ -1971,6 +1971,7 @@ static session_t *session_init(int argc, char **argv, Display *dpy,
 	      c2_list_postprocess(ps, ps->o.invert_color_list) &&
 	      c2_list_postprocess(ps, ps->o.opacity_rules) &&
 	      c2_list_postprocess(ps, ps->o.rounded_corners_blacklist) &&
+	      c2_list_postprocess(ps, ps->o.transition_rules) &&
 	      c2_list_postprocess(ps, ps->o.focus_blacklist))) {
 		log_error("Post-processing of conditionals failed, some of your rules "
 		          "might not work");
@@ -2350,6 +2351,7 @@ static void session_destroy(session_t *ps) {
 	free_wincondlst(&ps->o.paint_blacklist);
 	free_wincondlst(&ps->o.unredir_if_possible_blacklist);
 	free_wincondlst(&ps->o.rounded_corners_blacklist);
+	free_wincondlst(&ps->o.transition_rules);
 
 	// Free tracked atom list
 	{

src/win.c

@@ -1118,6 +1118,14 @@ void win_update_opacity_rule(session_t *ps, struct managed_win *w) {
 	w->opacity_is_set = is_set;
 }
 
+void win_update_transition_rule(session_t *ps, struct managed_win *w) {
+	void *val;
+	if (c2_match(ps, w, ps->o.transition_rules, &val)) {
+		// uses multiple casters to trick compiler to not give warnings
+		w->transition_direction = (unsigned int)(long)val;
+	}
+}
+
 /**
  * Function to be called on window data changes.
  *
@@ -1129,6 +1137,7 @@ void win_on_factor_change(session_t *ps, struct managed_win *w) {
 	// state of the window
 	win_update_focused(ps, w);
 
+	win_update_transition_rule(ps, w);
 	win_determine_shadow(ps, w);
 	win_determine_clip_shadow_above(ps, w);
 	win_determine_invert_color(ps, w);