From b4e9f729c301787239677b1bdd4235436bad99c7 Mon Sep 17 00:00:00 2001
From: qaqland <qaq@qaq.land>
Date: Sun, 11 May 2025 10:42:29 +0800
Subject: [PATCH] output: add "named" to multi-output-modes

---
 cage.c   |  3 +++
 output.c | 32 ++++++++++++++++++++++++--------
 server.h |  1 +
 3 files changed, 28 insertions(+), 8 deletions(-)

diff --git a/cage.c b/cage.c
index 40a675d..d0f896c 100644
--- a/cage.c
+++ b/cage.c
@@ -231,6 +231,7 @@ usage(FILE *file, const char *cage)
 		" -h\t Display this help message\n"
 		" -m extend Extend the display across all connected outputs (default)\n"
 		" -m last Use only the last connected output\n"
+		" -m named Use the output specified by the environment CAGE_OUTPUT_NAME, or fallback to last\n"
 		" -s\t Allow VT switching\n"
 		" -v\t Show the version number and exit\n"
 		"\n"
@@ -258,6 +259,8 @@ parse_args(struct cg_server *server, int argc, char *argv[])
 				server->output_mode = CAGE_MULTI_OUTPUT_MODE_LAST;
 			} else if (strcmp(optarg, "extend") == 0) {
 				server->output_mode = CAGE_MULTI_OUTPUT_MODE_EXTEND;
+			} else if (strcmp(optarg, "named") == 0) {
+				server->output_mode = CAGE_MULTI_OUTPUT_MODE_NAMED;
 			}
 			break;
 		case 's':
diff --git a/output.c b/output.c
index 5ccc939..4979155 100644
--- a/output.c
+++ b/output.c
@@ -238,9 +238,12 @@ output_destroy(struct cg_output *output)
 
 	free(output);
 
-	if (wl_list_empty(&server->outputs) && was_nested_output) {
-		server_terminate(server);
-	} else if (server->output_mode == CAGE_MULTI_OUTPUT_MODE_LAST && !wl_list_empty(&server->outputs)) {
+	if (wl_list_empty(&server->outputs)) {
+		if (was_nested_output) {
+			server_terminate(server);
+		}
+	} else if (server->output_mode == CAGE_MULTI_OUTPUT_MODE_LAST ||
+		   server->output_mode == CAGE_MULTI_OUTPUT_MODE_NAMED) {
 		struct cg_output *prev = wl_container_of(server->outputs.next, prev, link);
 		output_enable(prev);
 		view_position_all(server);
@@ -314,11 +317,6 @@ handle_new_output(struct wl_listener *listener, void *data)
 		}
 	}
 
-	if (server->output_mode == CAGE_MULTI_OUTPUT_MODE_LAST && wl_list_length(&server->outputs) > 1) {
-		struct cg_output *next = wl_container_of(output->link.next, next, link);
-		output_disable(next);
-	}
-
 	if (!wlr_xcursor_manager_load(server->seat->xcursor_manager, wlr_output->scale)) {
 		wlr_log(WLR_ERROR, "Cannot load XCursor theme for output '%s' with scale %f", wlr_output->name,
 			wlr_output->scale);
@@ -329,6 +327,24 @@ handle_new_output(struct wl_listener *listener, void *data)
 		output_layout_add_auto(output);
 	}
 
+	if (wl_list_length(&server->outputs) > 1) {
+		struct cg_output *next = wl_container_of(output->link.next, next, link);
+		const char *output_name = getenv("CAGE_OUTPUT_NAME");
+		switch (server->output_mode) {
+		case CAGE_MULTI_OUTPUT_MODE_NAMED:
+			if (output_name && strcmp(next->wlr_output->name, output_name) == 0) {
+				wl_list_remove(&next->link);
+				wl_list_insert(&server->outputs, &next->link);
+				next = output;
+			}
+			// fall through
+		case CAGE_MULTI_OUTPUT_MODE_LAST:
+			output_disable(next);
+			break;
+		case CAGE_MULTI_OUTPUT_MODE_EXTEND:;
+		}
+	}
+
 	view_position_all(output->server);
 	update_output_manager_config(output->server);
 }
diff --git a/server.h b/server.h
index 00c2a61..7a2f8cb 100644
--- a/server.h
+++ b/server.h
@@ -18,6 +18,7 @@
 enum cg_multi_output_mode {
 	CAGE_MULTI_OUTPUT_MODE_EXTEND,
 	CAGE_MULTI_OUTPUT_MODE_LAST,
+	CAGE_MULTI_OUTPUT_MODE_NAMED,
 };
 
 struct cg_server {