screencast: don't rely on the structure of xdpw_screencast_instance to convert formats

include/screencast_common.h

@@ -122,8 +122,7 @@ struct xdpw_wlr_output {
 };
 
 void randname(char *buf);
-enum spa_video_format xdpw_format_pw_from_wl_shm(
-	struct xdpw_screencast_instance *cast);
+enum spa_video_format xdpw_format_pw_from_wl_shm(enum wl_shm_format format);
 enum spa_video_format xdpw_format_pw_strip_alpha(enum spa_video_format format);
 
 enum xdpw_chooser_types get_chooser_type(const char *chooser_type);

src/screencast/pipewire_screencast.c

@@ -164,7 +164,7 @@ void xdpw_pwr_stream_create(struct xdpw_screencast_instance *cast) {
 		pw_loop_add_event(state->pw_loop, pwr_on_event, cast);
 	logprint(DEBUG, "pipewire: registered event %p", cast->event);
 
-	enum spa_video_format format = xdpw_format_pw_from_wl_shm(cast);
+	enum spa_video_format format = xdpw_format_pw_from_wl_shm(cast->simple_frame.format);
 	enum spa_video_format format_without_alpha =
 		xdpw_format_pw_strip_alpha(format);
 

src/screencast/screencast_common.c

@@ -12,9 +12,8 @@ void randname(char *buf) {
 	}
 }
 
-enum spa_video_format xdpw_format_pw_from_wl_shm(
-		struct xdpw_screencast_instance *cast) {
-	switch (cast->simple_frame.format) {
+enum spa_video_format xdpw_format_pw_from_wl_shm(enum wl_shm_format format) {
+	switch (format) {
 	case WL_SHM_FORMAT_ARGB8888:
 		return SPA_VIDEO_FORMAT_BGRA;
 	case WL_SHM_FORMAT_XRGB8888: