headless backend: add wlr_output_is_headless

backend/headless/output.c

@@ -82,6 +82,10 @@ static const struct wlr_output_impl output_impl = {
 	.swap_buffers = output_swap_buffers,
 };
 
+bool wlr_output_is_headless(struct wlr_output *wlr_output) {
+	return wlr_output->impl == &output_impl;
+}
+
 static int signal_frame(void *data) {
 	struct wlr_headless_output *output = data;
 	wl_signal_emit(&output->wlr_output.events.frame, &output->wlr_output);

include/backend/headless.h

@@ -3,7 +3,6 @@
 
 #include <wlr/backend/interface.h>
 #include <wlr/backend/headless.h>
-#include <wlr/types/wlr_output.h>
 
 struct wlr_headless_backend {
 	struct wlr_backend backend;

include/wlr/backend/headless.h

@@ -3,6 +3,7 @@
 
 #include <wlr/backend.h>
 #include <wlr/types/wlr_input_device.h>
+#include <wlr/types/wlr_output.h>
 
 struct wlr_backend *wlr_headless_backend_create(struct wl_display *display);
 struct wlr_output *wlr_headless_add_output(struct wlr_backend *backend,
@@ -11,5 +12,6 @@ struct wlr_input_device *wlr_headless_add_input_device(
 	struct wlr_backend *backend, enum wlr_input_device_type type);
 bool wlr_backend_is_headless(struct wlr_backend *backend);
 bool wlr_input_device_is_headless(struct wlr_input_device *device);
+bool wlr_output_is_headless(struct wlr_output *output);
 
 #endif