output: make attach_render and rollback_render optional

If these aren't provided by the backend, allocate a swapchain for the
output.

2 files changed, 4 insertions, 2 deletions

diff --git a/include/wlr/interfaces/wlr_output.h b/include/wlr/interfaces/wlr_output.h
index c74ea156..a727da61 100644
--- a/include/wlr/interfaces/wlr_output.h
+++ b/include/wlr/interfaces/wlr_output.h
@@ -17,8 +17,7 @@
 /**
  * A backend implementation of wlr_output.
  *
- * The functions commit, attach_render and rollback_render are mandatory. Other
- * functions are optional.
+ * The commit function is mandatory. Other functions are optional.
  */
 struct wlr_output_impl {
 	/**
diff --git a/include/wlr/types/wlr_output.h b/include/wlr/types/wlr_output.h
index dd5051c9..bab6d4ed 100644
--- a/include/wlr/types/wlr_output.h
+++ b/include/wlr/types/wlr_output.h
@@ -185,6 +185,9 @@ struct wlr_output {
 	struct wlr_buffer *cursor_front_buffer;
 	int software_cursor_locks; // number of locks forcing software cursors
 
+	struct wlr_swapchain *swapchain;
+	struct wlr_buffer *back_buffer;
+
 	struct wl_listener display_destroy;
 
 	void *data;