til,main: introduce ratio= --video setting

First stab at supporting explicit aspect ratios.

This performs the adjustment when needed in til_fb so it's
automatically applied to all fb backends.

The syntax is ratio=W:H with ratio=full being special cased for
when no aspect ratio adjustment is desired (just use whatever the
fb page dimensions are, usually specified via size= in the fb
backend's settings, or display native res when fullscreen=on)

For now when an aspect ratio is specified it always fits the
content within the alotted space... there is no
full-but-ratio-preserved-by-clipping-if-needed variant like widescreen
TVs often have.

3 files changed, 122 insertions, 8 deletions

diff --git a/src/main.c b/src/main.c
index df2d219..28f897f 100644
--- a/src/main.c
+++ b/src/main.c
@@ -9,6 +9,7 @@
 #include <stdint.h>
 #include <sys/time.h>
 #include <unistd.h>
+#include <math.h>
 
 #include "til.h"
 #include "til_args.h"
@@ -24,7 +25,7 @@
 
 /* Copyright (C) 2016 Vito Caputo <vcaputo@pengaru.com> */
 
-#define NUM_FB_PAGES	3
+#define NUM_FB_PAGES		3
 /* ^ By triple-buffering, we can have a page tied up being displayed, another
  * tied up submitted and waiting for vsync, and still not block on getting
  * another page so we can begin rendering another frame before vsync.  With
@@ -33,30 +34,33 @@
 
 #ifndef DEFAULT_VIDEO
 #ifdef HAVE_SDL
-#define DEFAULT_VIDEO	"sdl"
+#define DEFAULT_VIDEO		"sdl"
 #endif
 #endif
 
 #ifndef DEFAULT_VIDEO
 #ifdef  HAVE_DRM
-#define DEFAULT_VIDEO	"drm"
+#define DEFAULT_VIDEO		"drm"
 #endif
 #endif
 
 #ifndef DEFAULT_VIDEO
-#define DEFAULT_VIDEO	"mem"
+#define DEFAULT_VIDEO		"mem"
 #endif
 
+#define DEFAULT_VIDEO_RATIO	"full"
+
 #ifndef DEFAULT_AUDIO
 #ifdef HAVE_SDL
-#define DEFAULT_AUDIO	"sdl"
+#define DEFAULT_AUDIO		"sdl"
 #endif
 #endif
 
 #ifndef DEFAULT_AUDIO
-#define DEFAULT_AUDIO	"mem"
+#define DEFAULT_AUDIO		"mem"
 #endif
 
+
 extern til_fb_ops_t	drm_fb_ops;
 extern til_fb_ops_t	mem_fb_ops;
 extern til_fb_ops_t	sdl_fb_ops;
@@ -153,6 +157,33 @@ static int setup_audio(const til_settings_t *settings, til_setting_t **res_setti
 static int setup_video(const til_settings_t *settings, til_setting_t **res_setting, const til_setting_desc_t **res_desc, til_setup_t **res_setup)
 {
 	til_setting_t	*setting;
+	til_setting_t	*ratio;
+	const char	*ratio_values[] = {
+				"full",
+				"1:1",
+				"4:3",
+				"3:2",
+				"16:10",
+				"5:3",
+				"16:9",
+				"2:1",
+				"21:9",
+				"32:9",
+				NULL
+			};
+	const char	*ratio_annotations[] = {
+				"Fill fb with content, inheriting its ratio as-is (may stretch)",
+				"Square",
+				"CRT Monitor/TV (VGA/XGA)",
+				"35mm film, iphone",
+				"Widescreen monitor (WXGA)",
+				"Super 16mm film",
+				"Widescreen TV / newer laptops",
+				"Dominoes",
+				"Ultra-widescreen",
+				"Super ultra-widescreen",
+				NULL
+			};
 	const char	*video;
 	int		r;
 
@@ -188,6 +219,21 @@ static int setup_video(const til_settings_t *settings, til_setting_t **res_setti
 		return 1;
 	}
 
+	r = til_settings_get_and_describe_setting(settings,
+						  &(til_setting_spec_t){
+							.name = "Content aspect ratio (W:H)",
+							.key = "ratio",
+							.preferred = DEFAULT_VIDEO_RATIO,
+							.values = ratio_values,
+							.annotations = ratio_annotations,
+						  },
+						  &ratio,
+						  res_setting,
+						  res_desc);
+	if (r)
+		return r;
+
+
 	/* XXX: this is kind of hacky for now */
 #ifdef HAVE_DRM
 	if (!strcasecmp(video, "drm"))
@@ -215,6 +261,17 @@ static int setup_video(const til_settings_t *settings, til_setting_t **res_setti
 		if (r)
 			return r;
 
+		if (!strcasecmp(ratio->value, "full"))
+			setup->ratio = NAN;
+		else {
+			float	w, h;
+
+			if (sscanf(ratio->value, "%f:%f", &w, &h) != 2)
+				return til_setup_free_with_failed_setting_ret_err(&setup->til_setup, ratio, res_setting, -EINVAL);
+
+			setup->ratio = w / h;
+		}
+
 		*res_setup = &setup->til_setup;
 	}
 
diff --git a/src/til_fb.c b/src/til_fb.c
index 3c19ae5..cc07909 100644
--- a/src/til_fb.c
+++ b/src/til_fb.c
@@ -1,4 +1,5 @@
 #include <assert.h>
+#include <math.h>
 #include <pthread.h>
 #include <stddef.h>
 #include <stdlib.h>
@@ -126,6 +127,7 @@ typedef struct til_fb_t {
 	const til_fb_ops_t	*ops;
 	void			*ops_context;
 	int			n_pages;
+	float			ratio;
 
 	pthread_mutex_t		rebuild_mutex;
 	int			rebuild_pages;		/* counter of pages needing a rebuild */
@@ -157,6 +159,48 @@ typedef struct til_fb_t {
 static _til_fb_page_t * _til_fb_page_alloc(til_fb_t *fb);
 
 
+/* apply an aspect ratio to a fragment's frame,
+ * if ratio=NAN then the fragment is used as-is (e.g. for "ratio=full").
+ */
+static _til_fb_page_t * _til_fb_page_apply_ratio(_til_fb_page_t *page)
+{
+	til_fb_fragment_t	*fragment;
+	float			fragment_ratio, d;
+	float			ratio;
+
+	assert(page);
+	assert(page->fb);
+
+	ratio = page->fb->ratio;
+	fragment = &page->fragment.public;
+
+	assert(fragment->frame_width > 0 && fragment->frame_height > 0);
+	assert(ratio > 0.f);
+
+	if (isnan(ratio))
+		return page;
+
+	fragment_ratio = (float)fragment->frame_width / (float)fragment->frame_height;
+	d = fragment_ratio - ratio;
+	if (d < 0) { /* letterboxed, scale height */
+		unsigned	h = fragment->frame_width / ratio;
+
+		fragment->buf += ((fragment->frame_height - h) / 2) * fragment->pitch;
+		fragment->frame_height = h;
+		fragment->height = h;
+	} else if (d > 0) { /* pillarboxed, scale width */
+		unsigned	w = fragment->frame_height * ratio;
+
+		fragment->buf += ((fragment->frame_width - w) / 2);
+		fragment->stride += fragment->frame_width - w;
+		fragment->frame_width = w;
+		fragment->width = w;
+	}
+
+	return page;
+}
+
+
 /* Consumes ready pages queued via til_fb_page_put(), submits them to drm to flip
  * on vsync.  Produces inactive pages from those replaced, making them
  * available to til_fb_page_get(). */
@@ -205,6 +249,8 @@ int til_fb_flip(til_fb_t *fb)
 		fb->ops->page_free(fb, fb->ops_context, p->fb_ops_page);
 		p->fb_ops_page = fb->ops->page_alloc(fb, fb->ops_context, &p->fragment.public);
 		p->fragment.public.ops = &p->fragment.ops;
+		_til_fb_page_apply_ratio(p);
+
 		fb->rebuild_pages--;
 	}
 	pthread_mutex_unlock(&fb->rebuild_mutex);
@@ -366,7 +412,7 @@ static _til_fb_page_t * _til_fb_page_alloc(til_fb_t *fb)
 	else
 		fb->all_pages_tail = page;
 
-	return page;
+	return _til_fb_page_apply_ratio(page);
 }
 
 
@@ -561,7 +607,7 @@ int til_fb_new(const til_fb_ops_t *ops, const char *title, const til_video_setup
 	assert(ops->page_alloc);
 	assert(ops->page_free);
 	assert(ops->page_flip);
-	assert(!setup && setup->til_setup.creator == ops);
+	assert(setup && setup->til_setup.creator == ops);
 	assert(n_pages > 1);
 	assert(res_fb);
 
@@ -580,6 +626,15 @@ int til_fb_new(const til_fb_ops_t *ops, const char *title, const til_video_setup
 			goto fail;
 	}
 
+	/* TODO: fb should probably just take a reference on the setup,
+	 * the whole distinction of the ops-specific setup and intermediate
+	 * fb-common setup needs clarification, it's rather muddy right now esp.
+	 * with the advent of til_video_setup_t to facilitate a common ratio=
+	 * setting... with the backend allocating the whole setup, when it only
+	 * performs setup of its own little subset.  This all needs some tidying up
+	 * now that things have evolved so much on the video/fb side.
+	 */
+	fb->ratio = setup->ratio;
 	pthread_mutex_init(&fb->ready_mutex, NULL);
 	pthread_cond_init(&fb->ready_cond, NULL);
 	pthread_mutex_init(&fb->inactive_mutex, NULL);
diff --git a/src/til_video_setup.h b/src/til_video_setup.h
index 21c5844..f774c6f 100644
--- a/src/til_video_setup.h
+++ b/src/til_video_setup.h
@@ -5,6 +5,8 @@
 
 typedef struct til_video_setup_t {
 	til_setup_t	til_setup;
+
+	float		ratio;
 } til_video_setup_t;
 
 #endif