til_settings: always describe relevant settings

The existing iterative *_setup() interface only described
settings not found, quietly accepting usable settings already
present in the til_settings_t.

This worked fine for the existing interactive text setup thing,
but it's especially problematic for providing a GUI setup
frontend.

This commit makes it so the *_setup() methods always describe
undescribed settings they recognize, leaving the setup frontend
loop calling into the *_setup() methods to both apply the
description validation if wanted and actually tie the description
to respective setting returned by the _setup() methods as being
related to the returned description.

A new helper called til_settings_get_and_describe_value() has
been introduced primarily for use of module setup methods to
simplify this nonsense, replacing the til_settings_get_value()
calls and surrounding logic, but retaining the til_setting_desc_t
definitions largely verbatim.

This also results in discarding of some ad-hoc
til_setting_desc_check() calls, now that there's a centralized
place where settings become "described" (setup_interactively in
the case of rototiller).

Now a GUI frontend (like glimmer) would just provide its own
setup_interactively() equivalent for constructing its widgets for
a given *_setup() method's chain of returned descs.  Whereas in
the past this wasn't really feasible unless there was never going
to be pre-supplied settings.

I suspect the til_setting_desc_check() integration into
setup_interactively() needs more work, but I think this is good
enough for now and I'm out of spare time for the moment.

1 files changed, 2 insertions, 2 deletions

diff --git a/src/til.h b/src/til.h
index 6719693..02f8f2d 100644
--- a/src/til.h
+++ b/src/til.h
@@ -17,7 +17,7 @@ typedef struct til_module_t {
 	void	(*prepare_frame)(void *context, unsigned ticks, unsigned n_cpus, til_fb_fragment_t *fragment, til_fragmenter_t *res_fragmenter);
 	void	(*render_fragment)(void *context, unsigned ticks, unsigned cpu, til_fb_fragment_t *fragment);
 	void	(*finish_frame)(void *context, unsigned ticks, til_fb_fragment_t *fragment);
-	int	(*setup)(const til_settings_t *settings, til_setting_desc_t **next_setting);
+	int	(*setup)(const til_settings_t *settings, const til_setting_t **res_setting, const til_setting_desc_t **res_desc);
 	size_t	(*knobs)(void *context, til_knob_t **res_knobs);
 	char	*name;
 	char	*description;
@@ -32,6 +32,6 @@ const til_module_t * til_lookup_module(const char *name);
 void til_get_modules(const til_module_t ***res_modules, size_t *res_n_modules);
 void til_module_render(const til_module_t *module, void *context, unsigned ticks, til_fb_fragment_t *fragment);
 int til_module_create_context(const til_module_t *module, unsigned ticks, void **res_context);
-int til_module_setup(til_settings_t *settings, til_setting_desc_t **next_setting);
+int til_module_setup(til_settings_t *settings, const til_setting_t **res_setting, const til_setting_desc_t **res_desc);
 
 #endif