Improve tank pressure plot for computers that create "gaschange" events

This was exposed by the test dives, but it shows up in small ways with
real dives from some dive computers like the Suunto Vyper Air.

We now insert synthetic plot_info entries that match the gas change event;
to make this look smoother we insert either two events (one for the old
tank, one a second later for the new tank) if there is no sample at the
time of the event, or one additional event (and move the real sample back
by one second) if there is a sample at the time of the event.

This does expose another issue with some dives from Linus' computer where
the pressure in the samples dips below the end pressure noted for the tank
- which creates an odd "yellow up-tick" at the end of using the first tank
in the plot. Maybe we should not insert a synthetic "last of old tank"
event if we have a sample with valid pressure in the last NN seconds
before the gas change?

Signed-off-by: Dirk Hohndel <dirk@hohndel.org>

1 files changed, 96 insertions, 6 deletions

diff --git a/profile.c b/profile.c
index ad158fe8a..e5d8aa9b9 100644
--- a/profile.c
+++ b/profile.c
@@ -96,6 +96,24 @@ void set_source_rgb(struct graphics_context *gc, double r, double g, double b)
 
 #define ROUND_UP(x,y) ((((x)+(y)-1)/(y))*(y))
 
+/* debugging tool - not normally used */
+static void dump_pi (struct plot_info *pi)
+{
+	int i;
+
+	printf("pi:{nr:%d maxtime:%d meandepth:%d maxdepth:%d \n"
+		"    minpressure:%d maxpressure:%d endpressure:%d mintemp:%d maxtemp:%d\n",
+		pi->nr, pi->maxtime, pi->meandepth, pi->maxdepth,
+		pi->minpressure, pi->maxpressure, pi->endpressure, pi->mintemp, pi->maxtemp);
+	for (i = 0; i < pi->nr; i++)
+		printf("    entry[%d]:{same_cylinder:%d cylinderindex:%d sec:%d pressure:{%d,%d}\n"
+			"                temperature:%d depth:%d smoothed:%d}\n",
+			i, pi->entry[i].same_cylinder, pi->entry[i].cylinderindex, pi->entry[i].sec,
+			pi->entry[i].pressure[0], pi->entry[i].pressure[1],
+			pi->entry[i].temperature, pi->entry[i].depth, pi->entry[i].smoothed);
+	printf("   }\n");
+}
+
 /*
  * When showing dive profiles, we scale things to the
  * current dive. However, we don't scale past less than
@@ -978,6 +996,19 @@ static void check_gas_change_events(struct dive *dive, struct plot_info *pi)
 	set_cylinder_index(pi, i, cylinderindex, ~0u);
 }
 
+/* for computers that track gas changes through events */
+static int count_gas_change_events(struct dive *dive)
+{
+	int count = 0;
+	struct event *ev = get_next_gaschange(dive->events);
+
+	while (ev) {
+		count++;
+		ev = get_next_gaschange(ev->next);
+	}
+	return count;
+}
+
 /*
  * Create a plot-info with smoothing and ranged min/max
  *
@@ -989,41 +1020,96 @@ static struct plot_info *create_plot_info(struct dive *dive, int nr_samples, str
 {
 	int cylinderindex = -1;
 	int lastdepth, lastindex;
-	int i, nr = nr_samples + 4, sec, cyl;
-	size_t alloc_size = plot_info_size(nr);
+	int i, pi_idx, nr, sec, cyl;
+	size_t alloc_size;
 	struct plot_info *pi;
 	pr_track_t *track_pr[MAX_CYLINDERS] = {NULL, };
 	pr_track_t *pr_track, *current;
 	gboolean missing_pr = FALSE;
 	struct plot_data *entry = NULL;
+	struct event *ev;
 
+	/* we want to potentially add synthetic plot_info elements for the gas changes */
+	nr = nr_samples + 4 + 2 * count_gas_change_events(dive);
+	alloc_size = plot_info_size(nr);
 	pi = malloc(alloc_size);
 	if (!pi)
 		return pi;
 	memset(pi, 0, alloc_size);
 	pi->nr = nr;
+	pi_idx = 2; /* the two extra events at the start */
+	/* check for gas changes before the samples start */
+	ev = get_next_gaschange(dive->events);
+	while (ev && ev->time.seconds < dive_sample->time.seconds) {
+		entry = pi->entry + pi_idx;
+		entry->sec = ev->time.seconds;
+		entry->depth = 0; /* is that always correct ? */
+		pi_idx++;
+		ev = get_next_gaschange(ev->next);
+	}
+	if (ev && ev->time.seconds == dive_sample->time.seconds) {
+		/* we already have a sample at the time of the event */
+		ev = get_next_gaschange(ev->next);
+	}
 	sec = 0;
 	lastindex = 0;
 	lastdepth = -1;
 	for (i = 0; i < nr_samples; i++) {
 		int depth;
+		int delay = 0;
 		struct sample *sample = dive_sample+i;
 
-		entry = pi->entry + i + 2;
-		sec = entry->sec = sample->time.seconds;
+		entry = pi->entry + i + pi_idx;
+		while (ev && ev->time.seconds < sample->time.seconds) {
+			/* insert two fake plot info structures for the end of
+			 * the old tank and the start of the new tank */
+			entry->sec = ev->time.seconds;
+			(entry+1)->sec = ev->time.seconds + 1;
+			/* we need a fake depth - let's interpolate */
+			if (i) {
+				entry->depth = sample->depth.mm -
+					(sample->depth.mm - (sample-1)->depth.mm) / 2;
+			} else
+				entry->depth = sample->depth.mm;
+			(entry+1)->depth = entry->depth;
+			pi_idx += 2;
+			entry = pi->entry + i + pi_idx;
+			ev = get_next_gaschange(ev->next);
+		}
+		if (ev && ev->time.seconds == sample->time.seconds) {
+			/* we already have a sample at the time of the event
+			 * just add a new one for the old tank and delay the
+			 * real even by one second (to keep time monotonous) */
+			entry->sec = ev->time.seconds;
+			entry->depth = sample->depth.mm;
+			pi_idx++;
+			entry = pi->entry + i + pi_idx;
+			ev = get_next_gaschange(ev->next);
+			delay = 1;
+		}
+		sec = entry->sec = sample->time.seconds + delay;
 		depth = entry->depth = sample->depth.mm;
 		entry->cylinderindex = sample->cylinderindex;
 		SENSOR_PRESSURE(entry) = sample->cylinderpressure.mbar;
 		entry->temperature = sample->temperature.mkelvin;
 
 		if (depth || lastdepth)
-			lastindex = i+2;
+			lastindex = i+pi_idx;
 
 		lastdepth = depth;
 		if (depth > pi->maxdepth)
 			pi->maxdepth = depth;
 	}
-
+	entry = pi->entry + i + pi_idx;
+	/* are there still unprocessed gas changes? that would be very strange */
+	while (ev) {
+		entry->sec = ev->time.seconds;
+		entry->depth = 0; /* why are there gas changes after the dive is over? */
+		pi_idx++;
+		entry = pi->entry + i + pi_idx;
+		ev = get_next_gaschange(ev->next);
+	}
+	nr_samples += pi_idx - 2;
 	check_gas_change_events(dive, pi);
 
 	for (cyl = 0; cyl < MAX_CYLINDERS; cyl++) /* initialize the start pressures */
@@ -1072,6 +1158,8 @@ static struct plot_info *create_plot_info(struct dive *dive, int nr_samples, str
 	i = nr_samples + 2;
 	pi->entry[i].sec = sec + 20;
 	pi->entry[i+1].sec = sec + 40;
+	/* the number of actual entries - we may have allocated more if there
+	 * were gas change events, but this is how many were filled */
 	pi->nr = lastindex+1;
 	pi->maxtime = pi->entry[lastindex].sec;
 
@@ -1085,6 +1173,8 @@ static struct plot_info *create_plot_info(struct dive *dive, int nr_samples, str
 	}
 	for (cyl = 0; cyl < MAX_CYLINDERS; cyl++)
 		list_free(track_pr[cyl]);
+	if (0) /* awesome for debugging - not useful otherwise */
+		dump_pi(pi);
 	return analyze_plot_info(pi);
 }