rototiller: introduce module.finish_frame()

Add a hook for post-render serialized frame completion,
some of the renderers may have state to cleanup after rendering
a frame.

A future commit may change add a return value to control flow for
features like multi-pass rendering within a given module.

The raytracer for example may want to add concurrently executed
post filters, and having a non-void return from finish_frame()
would be a tidy way to tell rototiller "go back to prepare->render
for this context" as many times as necessary, keeping the pass state
in the context.

For now its return is void however, as I just need a cleanup hook
as the raytracer becomes more stateful per frame with a BIH spatial
index in the works.

2 files changed, 7 insertions, 3 deletions

diff --git a/src/rototiller.c b/src/rototiller.c
index c0a755b..079b0d4 100644
--- a/src/rototiller.c
+++ b/src/rototiller.c
@@ -70,10 +70,13 @@ static void module_render_page_threaded(rototiller_module_t *module, void *conte
 
 static void module_render_page(rototiller_module_t *module, void *context, threads_t *threads, fb_page_t *page)
 {
-	if (!module->prepare_frame)
-		return module->render_fragment(context, &page->fragment);
+	if (module->prepare_frame)
+		module_render_page_threaded(module, context, threads, page);
+	else
+		module->render_fragment(context, &page->fragment);
 
-	module_render_page_threaded(module, context, threads, page);
+	if (module->finish_frame)
+		module->finish_frame(context, &page->fragment);
 }
 
 
diff --git a/src/rototiller.h b/src/rototiller.h
index beafc52..84b3842 100644
--- a/src/rototiller.h
+++ b/src/rototiller.h
@@ -12,6 +12,7 @@ typedef struct rototiller_module_t {
 	void	(*destroy_context)(void *context);
 	void	(*prepare_frame)(void *context, unsigned n_cpus, fb_fragment_t *fragment, rototiller_fragmenter_t *res_fragmenter);
 	void	(*render_fragment)(void *context, fb_fragment_t *fragment);
+	void	(*finish_frame)(void *context, fb_fragment_t *fragment);
 	char	*name;
 	char	*description;
 	char	*author;