From 6ad73a8f043be283c07df34c6a5a43fee1b444e8 Mon Sep 17 00:00:00 2001
From: Dirk Hohndel <dirk@hohndel.org>
Date: Sat, 10 Nov 2012 11:40:35 +0100
Subject: Improve logic handling events

We now throw away redundant events, just as we throw away other redundant
data coming from the dive computer. Events are considered redundant if
they are less than 61 seconds apart and identical.

This also improves the display of the remaining events in the profile as
we now show the value of the event, if it is present (for example for a
deco event we show the duration of the deepest stop).

Finally, for events that define a range (so they set the beginning flag
and assume and end flag some time later) we no loger show the triangle but
assume that some other code handles visualizing them (as happens for the
ceiling events).

Signed-off-by: Dirk Hohndel <dirk@hohndel.org>
---
 dive.c | 61 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 61 insertions(+)

(limited to 'dive.c')

diff --git a/dive.c b/dive.c
index c855acef8..06d15efdd 100644
--- a/dive.c
+++ b/dive.c
@@ -373,6 +373,30 @@ static void sanitize_cylinder_info(struct dive *dive)
 	}
 }
 
+/* some events should never be thrown away */
+static gboolean is_potentially_redundant(struct event *event)
+{
+	if (!strcmp(event->name, "gaschange"))
+		return FALSE;
+	return TRUE;
+}
+
+/* match just by name - we compare the details in the code that uses this helper */
+static struct event *find_previous_event(struct dive *dive, struct event *event)
+{
+	struct event *ev = dive->events;
+	struct event *previous = NULL;
+
+	if (!event->name)
+		return NULL;
+	while (ev && ev != event) {
+		if(ev->name && !strcmp(ev->name, event->name))
+			previous = ev;
+		ev = ev->next;
+	}
+	return previous;
+}
+
 struct dive *fixup_dive(struct dive *dive)
 {
 	int i,j;
@@ -384,6 +408,7 @@ struct dive *fixup_dive(struct dive *dive)
 	int lastdepth = 0;
 	int lasttemp = 0, lastpressure = 0;
 	int pressure_delta[MAX_CYLINDERS] = {INT_MAX, };
+	struct event *event;
 
 	add_people(dive->buddy);
 	add_people(dive->divemaster);
@@ -514,6 +539,42 @@ struct dive *fixup_dive(struct dive *dive)
 		add_weightsystem_description(ws);
 	}
 
+	/* events are stored as a linked list, so the concept of
+	 * "consecutive, identical events" is somewhat hard to
+	 * implement correctly (especially given that on some dive
+	 * computers events are asynchronous, so they can come in
+	 * between what would be the non-constant sample rate).
+	 *
+	 * So what we do is that we throw away clearly redundant
+	 * events that are fewer than 61 seconds apart (assuming there
+	 * is no dive computer with a sample rate of more than 60
+	 * seconds... that would be pretty pointless to plot the
+	 * profile with)
+	 * We first only mark the events for deletion so that we
+	 * still know when the previous event happened. */
+	event = dive->events;
+	while (event) {
+		struct event *prev;
+		if (is_potentially_redundant(event)) {
+			prev = find_previous_event(dive, event);
+			if (prev && prev->value == event->value &&
+			    prev->flags == event->flags &&
+			    event->time.seconds - prev->time.seconds < 61)
+				event->deleted = TRUE;
+		}
+		event = event->next;
+	}
+	event = dive->events;
+	while (event) {
+		if (event->next && event->next->deleted) {
+			struct event *nextnext = event->next->next;
+			free(event->next);
+			event->next = nextnext;
+		} else {
+			event = event->next;
+		}
+	}
+
 	return dive;
 }
 
-- 
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