X-Git-Url: http://git.tdb.fi/?a=blobdiff_plain;f=profile.c;h=ad158fe8a1f9aaafb40b792f31dea13667594f5f;hb=edbba678b3cdc8f06a84a965b04f13ef1f4ecaab;hp=2edaf694cd5f429387d5e3cba08f32c7fd3aeda8;hpb=ab3c6731bea1043e35d450b227fc2f41e137c397;p=ext%2Fsubsurface.git

diff --git a/profile.c b/profile.c
index 2edaf69..ad158fe 100644
--- a/profile.c
+++ b/profile.c
@@ -22,12 +22,18 @@ struct plot_info {
 	int maxtime;
 	int meandepth, maxdepth;
 	int minpressure, maxpressure;
+	int endpressure; /* start pressure better be max pressure */
 	int mintemp, maxtemp;
 	struct plot_data {
+		unsigned int same_cylinder:1;
+		unsigned int cylinderindex;
 		int sec;
-		int pressure, temperature;
+		/* pressure[0] is sensor pressure
+		 * pressure[1] is interpolated pressure */
+		int pressure[2];
+		int temperature;
 		/* Depth info */
-		int val;
+		int depth;
 		int smoothed;
 		velocity_t velocity;
 		struct plot_data *min[3];
@@ -35,6 +41,10 @@ struct plot_info {
 		int avg[3];
 	} entry[];
 };
+#define SENSOR_PR 0
+#define INTERPOLATED_PR 1
+#define SENSOR_PRESSURE(_entry) (_entry)->pressure[SENSOR_PR]
+#define INTERPOLATED_PRESSURE(_entry) (_entry)->pressure[INTERPOLATED_PR]
 
 /* convert velocity to colors */
 typedef struct { double r, g, b; } rgb_t;
@@ -156,17 +166,85 @@ static void plot_text(struct graphics_context *gc, const text_render_options_t *
 	cairo_show_text(cr, buffer);
 }
 
+struct ev_select {
+	char *ev_name;
+	gboolean plot_ev;
+};
+static struct ev_select *ev_namelist;
+static int evn_allocated;
+static int evn_used;
+
+void evn_foreach(void (*callback)(const char *, int *, void *), void *data)
+{
+	int i;
+
+	for (i = 0; i < evn_used; i++) {
+		callback(ev_namelist[i].ev_name, &ev_namelist[i].plot_ev, data);
+	}
+}
+
+void remember_event(const char *eventname)
+{
+	int i=0, len;
+
+	if (!eventname || (len = strlen(eventname)) == 0)
+		return;
+	while (i < evn_used) {
+		if (!strncmp(eventname,ev_namelist[i].ev_name,len))
+			return;
+		i++;
+	}
+	if (evn_used == evn_allocated) {
+		evn_allocated += 10;
+		ev_namelist = realloc(ev_namelist, evn_allocated * sizeof(struct ev_select));
+		if (! ev_namelist)
+			/* we are screwed, but let's just bail out */
+			return;
+	}
+	ev_namelist[evn_used].ev_name = strdup(eventname);
+	ev_namelist[evn_used].plot_ev = TRUE;
+	evn_used++;
+}
+
 static void plot_one_event(struct graphics_context *gc, struct plot_info *pi, struct event *event, const text_render_options_t *tro)
 {
 	int i, depth = 0;
-
+	int x,y;
+
+	/* is plotting this event disabled? */
+	if (event->name) {
+		for (i = 0; i < evn_used; i++) {
+			if (! strcmp(event->name, ev_namelist[i].ev_name)) {
+				if (ev_namelist[i].plot_ev)
+					break;
+				else
+					return;
+			}
+		}
+	}
 	for (i = 0; i < pi->nr; i++) {
 		struct plot_data *data = pi->entry + i;
 		if (event->time.seconds < data->sec)
 			break;
-		depth = data->val;
+		depth = data->depth;
 	}
-	plot_text(gc, tro, event->time.seconds, depth, "%s", event->name);
+	/* draw a little tirangular marker and attach tooltip */
+	x = SCALEX(gc, event->time.seconds);
+	y = SCALEY(gc, depth);
+	set_source_rgba(gc, 1.0, 1.0, 0.1, 0.8);
+	cairo_move_to(gc->cr, x-15, y+6);
+	cairo_line_to(gc->cr, x-3  , y+6);
+	cairo_line_to(gc->cr, x-9, y-6);
+	cairo_line_to(gc->cr, x-15, y+6);
+	cairo_stroke_preserve(gc->cr);
+	cairo_fill(gc->cr);
+	set_source_rgba(gc, 0.0, 0.0, 0.0, 0.8);
+	cairo_move_to(gc->cr, x-9, y-3);
+	cairo_line_to(gc->cr, x-9, y+1);
+	cairo_move_to(gc->cr, x-9, y+4);
+	cairo_line_to(gc->cr, x-9, y+4);
+	cairo_stroke(gc->cr);
+	attach_tooltip(x-15, y-6, 12, 12, event->name);
 }
 
 static void plot_events(struct graphics_context *gc, struct plot_info *pi, struct dive *dive)
@@ -188,9 +266,9 @@ static void render_depth_sample(struct graphics_context *gc, struct plot_data *e
 	int sec = entry->sec, decimals;
 	double d;
 
-	d = get_depth_units(entry->val, &decimals, NULL);
+	d = get_depth_units(entry->depth, &decimals, NULL);
 
-	plot_text(gc, tro, sec, entry->val, "%.*f", decimals, d);
+	plot_text(gc, tro, sec, entry->depth, "%.*f", decimals, d);
 }
 
 static void plot_text_samples(struct graphics_context *gc, struct plot_info *pi)
@@ -198,18 +276,26 @@ static void plot_text_samples(struct graphics_context *gc, struct plot_info *pi)
 	static const text_render_options_t deep = {14, 1.0, 0.2, 0.2, CENTER, TOP};
 	static const text_render_options_t shallow = {14, 1.0, 0.2, 0.2, CENTER, BOTTOM};
 	int i;
+	int last = -1;
 
 	for (i = 0; i < pi->nr; i++) {
 		struct plot_data *entry = pi->entry + i;
 
-		if (entry->val < 2000)
+		if (entry->depth < 2000)
 			continue;
 
-		if (entry == entry->max[2])
+		if ((entry == entry->max[2]) && entry->depth != last) {
 			render_depth_sample(gc, entry, &deep);
+			last = entry->depth;
+		}
 
-		if (entry == entry->min[2])
+		if ((entry == entry->min[2]) && entry->depth != last) {
 			render_depth_sample(gc, entry, &shallow);
+			last = entry->depth;
+		}
+
+		if (entry->depth != last)
+			last = -1;
 	}
 }
 
@@ -248,13 +334,13 @@ static void plot_minmax_profile_minute(struct graphics_context *gc, struct plot_
 	struct plot_data *entry = pi->entry;
 
 	set_source_rgba(gc, 1, 0.2, 1, a);
-	move_to(gc, entry->sec, entry->min[index]->val);
+	move_to(gc, entry->sec, entry->min[index]->depth);
 	for (i = 1; i < pi->nr; i++) {
 		entry++;
-		line_to(gc, entry->sec, entry->min[index]->val);
+		line_to(gc, entry->sec, entry->min[index]->depth);
 	}
 	for (i = 1; i < pi->nr; i++) {
-		line_to(gc, entry->sec, entry->max[index]->val);
+		line_to(gc, entry->sec, entry->max[index]->depth);
 		entry--;
 	}
 	cairo_close_path(gc->cr);
@@ -272,23 +358,43 @@ static void plot_minmax_profile(struct graphics_context *gc, struct plot_info *p
 
 static void plot_depth_profile(struct graphics_context *gc, struct plot_info *pi)
 {
-	int i;
+	int i, incr;
 	cairo_t *cr = gc->cr;
 	int sec, depth;
 	struct plot_data *entry;
 	int maxtime, maxdepth, marker;
+	int increments[4] = { 5*60, 10*60, 15*60, 30*60 };
 
 	/* Get plot scaling limits */
 	maxtime = get_maxtime(pi);
 	maxdepth = get_maxdepth(pi);
 
-	/* Time markers: every 5 min */
+	/* Time markers: at most every 5 min, but no more than 12 markers
+	 * and for convenience we do 5, 10, 15 or 30 min intervals.
+	 * This allows for 6h dives - enough (I hope) for even the craziest
+	 * divers - but just in case, for those 8h depth-record-breaking dives,
+	 * we double the interval if this still doesn't get us to 12 or fewer
+	 * time markers */
+	i = 0;
+	while (maxtime / increments[i] > 12 && i < 4)
+		i++;
+	incr = increments[i];
+	while (maxtime / incr > 12)
+		incr *= 2;
+
 	gc->leftx = 0; gc->rightx = maxtime;
 	gc->topy = 0; gc->bottomy = 1.0;
-	for (i = 5*60; i < maxtime; i += 5*60) {
+	set_source_rgba(gc, 1, 1, 1, 0.5);
+	for (i = incr; i < maxtime; i += incr) {
 		move_to(gc, i, 0);
 		line_to(gc, i, 1);
 	}
+	cairo_stroke(cr);
+
+	/* now the text on every second time marker */
+	text_render_options_t tro = {10, 0.2, 1.0, 0.2, CENTER, TOP};
+	for (i = incr; i < maxtime; i += 2 * incr)
+		plot_text(gc, &tro, i, 1, "%d", i/60);
 
 	/* Depth markers: every 30 ft or 10 m*/
 	gc->leftx = 0; gc->rightx = 1.0;
@@ -333,7 +439,7 @@ static void plot_depth_profile(struct graphics_context *gc, struct plot_info *pi
 	entry = pi->entry;
 	move_to(gc, 0, 0);
 	for (i = 0; i < pi->nr; i++, entry++)
-		line_to(gc, entry->sec, entry->val);
+		line_to(gc, entry->sec, entry->depth);
 	cairo_close_path(gc->cr);
 	if (gc->printer) {
 		set_source_rgba(gc, 1, 1, 1, 0.2);
@@ -353,9 +459,9 @@ static void plot_depth_profile(struct graphics_context *gc, struct plot_info *pi
 		 * representing the vertical velocity, so we need to
 		 * chop this into short segments */
 		rgb_t color = rgb[entry->velocity];
-		depth = entry->val;
+		depth = entry->depth;
 		set_source_rgb(gc, color.r, color.g, color.b);
-		move_to(gc, entry[-1].sec, entry[-1].val);
+		move_to(gc, entry[-1].sec, entry[-1].depth);
 		line_to(gc, sec, depth);
 		cairo_stroke(cr);
 	}
@@ -387,19 +493,13 @@ static int setup_temperature_limits(struct graphics_context *gc, struct plot_inf
 
 static void plot_single_temp_text(struct graphics_context *gc, int sec, int mkelvin)
 {
-	int deg;
+	double deg;
 	const char *unit;
 	static const text_render_options_t tro = {12, 0.2, 0.2, 1.0, LEFT, TOP};
-	temperature_t temperature = { mkelvin };
 
-	if (output_units.temperature == FAHRENHEIT) {
-		deg = to_F(temperature);
-		unit = UTF8_DEGREE "F";
-	} else {
-		deg = to_C(temperature);
-		unit = UTF8_DEGREE "C";
-	}
-	plot_text(gc, &tro, sec, temperature.mkelvin, "%d%s", deg, unit);
+	deg = get_temp_units(mkelvin, &unit);
+
+	plot_text(gc, &tro, sec, mkelvin, "%d%s", (int)(deg + 0.5), unit);
 }
 
 static void plot_temperature_text(struct graphics_context *gc, struct plot_info *pi)
@@ -468,63 +568,109 @@ static int get_cylinder_pressure_range(struct graphics_context *gc, struct plot_
 	return pi->maxpressure != 0;
 }
 
-static void plot_cylinder_pressure(struct graphics_context *gc, struct plot_info *pi)
+static void plot_pressure_helper(struct graphics_context *gc, struct plot_info *pi, int type)
 {
 	int i;
+	int lift_pen = FALSE;
 
-	if (!get_cylinder_pressure_range(gc, pi))
-		return;
-
-	set_source_rgba(gc, 0.2, 1.0, 0.2, 0.80);
-
-	move_to(gc, 0, pi->maxpressure);
-	for (i = 1; i < pi->nr; i++) {
+	for (i = 0; i < pi->nr; i++) {
 		int mbar;
 		struct plot_data *entry = pi->entry + i;
 
-		mbar = entry->pressure;
-		if (!mbar)
+		mbar = entry->pressure[type];
+		if (!entry->same_cylinder)
+			lift_pen = TRUE;
+		if (!mbar) {
+			lift_pen = TRUE;
 			continue;
-		line_to(gc, entry->sec, mbar);
+		}
+		if (lift_pen) {
+			if (i > 0 && entry->same_cylinder) {
+				/* if we have a previous event from the same tank,
+				 * draw at least a short line .
+				 * This uses the implementation detail that the
+				 * type is either 0 or 1 */
+				int prev_pr;
+				prev_pr = (entry-1)->pressure[type] ? : (entry-1)->pressure[1 - type];
+				move_to(gc, (entry-1)->sec, prev_pr);
+				line_to(gc, entry->sec, mbar);
+			} else
+				move_to(gc, entry->sec, mbar);
+			lift_pen = FALSE;
+		}
+		else
+			line_to(gc, entry->sec, mbar);
 	}
-	line_to(gc, pi->maxtime, pi->minpressure);
 	cairo_stroke(gc->cr);
+
+}
+
+static void plot_cylinder_pressure(struct graphics_context *gc, struct plot_info *pi)
+{
+	if (!get_cylinder_pressure_range(gc, pi))
+		return;
+
+	/* first plot the pressure readings we have from the dive computer */
+	set_source_rgba(gc, 0.2, 1.0, 0.2, 0.80);
+	plot_pressure_helper(gc, pi, SENSOR_PR);
+
+	/* then, in a different color, the interpolated values */
+	set_source_rgba(gc, 1.0, 1.0, 0.2, 0.80);
+	plot_pressure_helper(gc, pi, INTERPOLATED_PR);
 }
 
-static int mbar_to_PSI(int mbar)
+static void plot_pressure_value(struct graphics_context *gc, int mbar, int sec,
+				int xalign, int yalign)
 {
-	pressure_t p = {mbar};
-	return to_PSI(p);
+	int pressure;
+	const char *unit;
+
+	pressure = get_pressure_units(mbar, &unit);
+	text_render_options_t tro = {10, 0.2, 1.0, 0.2, xalign, yalign};
+	plot_text(gc, &tro, sec, mbar, "%d %s", pressure, unit);
 }
 
 static void plot_cylinder_pressure_text(struct graphics_context *gc, struct plot_info *pi)
 {
-	if (get_cylinder_pressure_range(gc, pi)) {
-		int start, end;
-		const char *unit = "bar";
+	int i;
+	int mbar, cyl;
+	int seen_cyl[MAX_CYLINDERS] = { FALSE, };
+	int last_pressure[MAX_CYLINDERS] = { 0, };
+	int last_time[MAX_CYLINDERS] = { 0, };
+	struct plot_data *entry;
 
-		switch (output_units.pressure) {
-		case PASCAL:
-			start = pi->maxpressure * 100;
-			end = pi->minpressure * 100;
-			unit = "pascal";
-			break;
-		case BAR:
-			start = (pi->maxpressure + 500) / 1000;
-			end = (pi->minpressure + 500) / 1000;
-			unit = "bar";
-			break;
-		case PSI:
-			start = mbar_to_PSI(pi->maxpressure);
-			end = mbar_to_PSI(pi->minpressure);
-			unit = "psi";
-			break;
+	if (!get_cylinder_pressure_range(gc, pi))
+		return;
+
+	/* only loop over the actual events from the dive computer */
+	for (i = 2; i < pi->nr; i++) {
+		entry = pi->entry + i;
+
+		if (!entry->same_cylinder) {
+			cyl = entry->cylinderindex;
+			if (!seen_cyl[cyl]) {
+				mbar = SENSOR_PRESSURE(entry) ? : INTERPOLATED_PRESSURE(entry);
+				plot_pressure_value(gc, mbar, entry->sec, LEFT, BOTTOM);
+				seen_cyl[cyl] = TRUE;
+			}
+			if (i > 2) {
+				/* remember the last pressure and time of
+				 * the previous cylinder */
+				cyl = (entry - 1)->cylinderindex;
+				last_pressure[cyl] =
+					SENSOR_PRESSURE(entry - 1) ? : INTERPOLATED_PRESSURE(entry - 1);
+				last_time[cyl] = (entry - 1)->sec;
+			}
 		}
+	}
+	cyl = entry->cylinderindex;
+	last_pressure[cyl] = SENSOR_PRESSURE(entry) ? : INTERPOLATED_PRESSURE(entry);
+	last_time[cyl] = entry->sec;
 
-		text_render_options_t tro = {10, 0.2, 1.0, 0.2, LEFT, TOP};
-		plot_text(gc, &tro, 0, pi->maxpressure, "%d %s", start, unit);
-		plot_text(gc, &tro, pi->maxtime, pi->minpressure,
-			  "%d %s", end, unit);
+	for (cyl = 0; cyl < MAX_CYLINDERS; cyl++) {
+		if (last_time[cyl]) {
+			plot_pressure_value(gc, last_pressure[cyl], last_time[cyl], CENTER, TOP);
+		}
 	}
 }
 
@@ -545,17 +691,17 @@ static void analyze_plot_info_minmax_minute(struct plot_data *entry, struct plot
 
 	/* Then go forward until we hit an entry past the time */
 	min = max = p;
-	avg = p->val;
+	avg = p->depth;
 	nr = 1;
 	while (++p < last) {
-		int val = p->val;
+		int depth = p->depth;
 		if (p->sec > time + seconds)
 			break;
-		avg += val;
+		avg += depth;
 		nr ++;
-		if (val < min->val)
+		if (depth < min->depth)
 			min = p;
-		if (val > max->val)
+		if (depth > max->depth)
 			max = p;
 	}
 	entry->min[index] = min;
@@ -605,7 +751,7 @@ static struct plot_info *analyze_plot_info(struct plot_info *pi)
 	/* Do pressure min/max based on the non-surface data */
 	for (i = 0; i < nr; i++) {
 		struct plot_data *entry = pi->entry+i;
-		int pressure = entry->pressure;
+		int pressure = SENSOR_PRESSURE(entry) ? : INTERPOLATED_PRESSURE(entry);
 		int temperature = entry->temperature;
 
 		if (pressure) {
@@ -626,22 +772,22 @@ static struct plot_info *analyze_plot_info(struct plot_info *pi)
 	/* Smoothing function: 5-point triangular smooth */
 	for (i = 2; i < nr; i++) {
 		struct plot_data *entry = pi->entry+i;
-		int val;
+		int depth;
 
 		if (i < nr-2) {
-			val = entry[-2].val + 2*entry[-1].val + 3*entry[0].val + 2*entry[1].val + entry[2].val;
-			entry->smoothed = (val+4) / 9;
+			depth = entry[-2].depth + 2*entry[-1].depth + 3*entry[0].depth + 2*entry[1].depth + entry[2].depth;
+			entry->smoothed = (depth+4) / 9;
 		}
 		/* vertical velocity in mm/sec */
 		/* Linus wants to smooth this - let's at least look at the samples that aren't FAST or CRAZY */
 		if (entry[0].sec - entry[-1].sec) {
-			entry->velocity = velocity((entry[0].val - entry[-1].val) / (entry[0].sec - entry[-1].sec));
+			entry->velocity = velocity((entry[0].depth - entry[-1].depth) / (entry[0].sec - entry[-1].sec));
                         /* if our samples are short and we aren't too FAST*/
 			if (entry[0].sec - entry[-1].sec < 15 && entry->velocity < FAST) {
 				int past = -2;
 				while (i+past > 0 && entry[0].sec - entry[past].sec < 15)
 					past--;
-				entry->velocity = velocity((entry[0].val - entry[past].val) / 
+				entry->velocity = velocity((entry[0].depth - entry[past].depth) / 
 							(entry[0].sec - entry[past].sec));
 			}
 		} else
@@ -657,6 +803,181 @@ static struct plot_info *analyze_plot_info(struct plot_info *pi)
 	return pi;
 }
 
+/*
+ * simple structure to track the beginning and end tank pressure as
+ * well as the integral of depth over time spent while we have no
+ * pressure reading from the tank */
+typedef struct pr_track_struct pr_track_t;
+struct pr_track_struct {
+	int start;
+	int end;
+	int t_start;
+	int t_end;
+	double pressure_time;
+	pr_track_t *next;
+};
+
+static pr_track_t *pr_track_alloc(int start, int t_start) {
+	pr_track_t *pt = malloc(sizeof(pr_track_t));
+	pt->start = start;
+	pt->t_start = t_start;
+	pt->end = 0;
+	pt->t_end = 0;
+	pt->pressure_time = 0.0;
+	pt->next = NULL;
+	return pt;
+}
+
+/* poor man's linked list */
+static pr_track_t *list_last(pr_track_t *list)
+{
+	pr_track_t *tail = list;
+	if (!tail)
+		return NULL;
+	while (tail->next) {
+		tail = tail->next;
+	}
+	return tail;
+}
+
+static pr_track_t *list_add(pr_track_t *list, pr_track_t *element)
+{
+	pr_track_t *tail = list_last(list);
+	if (!tail)
+		return element;
+	tail->next = element;
+	return list;
+}
+
+static void list_free(pr_track_t *list)
+{
+	if (!list)
+		return;
+	list_free(list->next);
+	free(list);
+}
+
+static void fill_missing_tank_pressures(struct dive *dive, struct plot_info *pi,
+					pr_track_t **track_pr)
+{
+	pr_track_t *list = NULL;
+	pr_track_t *nlist = NULL;
+	double pt, magic;
+	int cyl, i;
+	struct plot_data *entry;
+	int cur_pr[MAX_CYLINDERS];
+
+	for (cyl = 0; cyl < MAX_CYLINDERS; cyl++) {
+		cur_pr[cyl] = track_pr[cyl]->start;
+	}
+
+	/* The first two are "fillers" */
+	for (i = 2; i < pi->nr; i++) {
+		entry = pi->entry + i;
+		if (SENSOR_PRESSURE(entry)) {
+			cur_pr[entry->cylinderindex] = SENSOR_PRESSURE(entry);
+		} else {
+			if(!list || list->t_end < entry->sec) {
+				nlist = track_pr[entry->cylinderindex];
+				list = NULL;
+				while (nlist && nlist->t_start <= entry->sec) {
+					list = nlist;
+					nlist = list->next;
+				}
+				/* there may be multiple segments - so
+				 * let's assemble the length */
+				nlist = list;
+				pt = list->pressure_time;
+				while (!nlist->end) {
+					nlist = nlist->next;
+					if (!nlist) {
+						/* oops - we have no end pressure,
+						 * so this means this is a tank without
+						 * gas consumption information */
+						break;
+					}
+					pt += nlist->pressure_time;
+				}
+				if (!nlist) {
+					/* just continue without calculating
+					 * interpolated values */
+					list = NULL;
+					continue;
+				}
+				magic = (nlist->end - cur_pr[entry->cylinderindex]) / pt;				}
+			if (pt != 0.0) {
+				double cur_pt = (entry->sec - (entry-1)->sec) *
+					(1 + entry->depth / 10000.0);
+				INTERPOLATED_PRESSURE(entry) =
+					cur_pr[entry->cylinderindex] + cur_pt * magic;
+				cur_pr[entry->cylinderindex] = INTERPOLATED_PRESSURE(entry);
+			}
+		}
+	}
+}
+
+static int get_cylinder_index(struct dive *dive, struct event *ev)
+{
+	int i;
+
+	/*
+	 * Try to find a cylinder that matches the O2 percentage
+	 * in the gas change event 'value' field.
+	 *
+	 * Crazy suunto gas change events. We really should do
+	 * this in libdivecomputer or something.
+	 */
+	for (i = 0; i < MAX_CYLINDERS; i++) {
+		cylinder_t *cyl = dive->cylinder+i;
+		int o2 = (cyl->gasmix.o2.permille + 5) / 10;
+		if (o2 == ev->value)
+			return i;
+	}
+
+	return 0;
+}
+
+static struct event *get_next_gaschange(struct event *event)
+{
+	while (event) {
+		if (!strcmp(event->name, "gaschange"))
+			return event;
+		event = event->next;
+	}
+	return event;
+}
+
+static int set_cylinder_index(struct plot_info *pi, int i, int cylinderindex, unsigned int end)
+{
+	while (i < pi->nr) {
+		struct plot_data *entry = pi->entry+i;
+		if (entry->sec > end)
+			break;
+		if (entry->cylinderindex != cylinderindex) {
+			entry->cylinderindex = cylinderindex;
+			entry->pressure[0] = 0;
+		}
+		i++;
+	}
+	return i;
+}
+
+static void check_gas_change_events(struct dive *dive, struct plot_info *pi)
+{
+	int i = 0, cylinderindex = 0;
+	struct event *ev = get_next_gaschange(dive->events);
+
+	if (!ev)
+		return;
+
+	do {
+		i = set_cylinder_index(pi, i, cylinderindex, ev->time.seconds);
+		cylinderindex = get_cylinder_index(dive, ev);
+		ev = get_next_gaschange(ev->next);
+	} while (ev);
+	set_cylinder_index(pi, i, cylinderindex, ~0u);
+}
+
 /*
  * Create a plot-info with smoothing and ranged min/max
  *
@@ -664,12 +985,17 @@ static struct plot_info *analyze_plot_info(struct plot_info *pi)
  * sides, so that you can do end-points without having to worry
  * about it.
  */
-static struct plot_info *create_plot_info(struct dive *dive)
+static struct plot_info *create_plot_info(struct dive *dive, int nr_samples, struct sample *dive_sample)
 {
+	int cylinderindex = -1;
 	int lastdepth, lastindex;
-	int i, nr = dive->samples + 4, sec;
+	int i, nr = nr_samples + 4, sec, cyl;
 	size_t alloc_size = plot_info_size(nr);
 	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;
 
 	pi = malloc(alloc_size);
 	if (!pi)
@@ -679,14 +1005,15 @@ static struct plot_info *create_plot_info(struct dive *dive)
 	sec = 0;
 	lastindex = 0;
 	lastdepth = -1;
-	for (i = 0; i < dive->samples; i++) {
+	for (i = 0; i < nr_samples; i++) {
 		int depth;
-		struct sample *sample = dive->sample+i;
-		struct plot_data *entry = pi->entry + i + 2;
+		struct sample *sample = dive_sample+i;
 
+		entry = pi->entry + i + 2;
 		sec = entry->sec = sample->time.seconds;
-		depth = entry->val = sample->depth.mm;
-		entry->pressure = sample->cylinderpressure.mbar;
+		depth = entry->depth = sample->depth.mm;
+		entry->cylinderindex = sample->cylinderindex;
+		SENSOR_PRESSURE(entry) = sample->cylinderpressure.mbar;
 		entry->temperature = sample->temperature.mkelvin;
 
 		if (depth || lastdepth)
@@ -696,32 +1023,93 @@ static struct plot_info *create_plot_info(struct dive *dive)
 		if (depth > pi->maxdepth)
 			pi->maxdepth = depth;
 	}
-	if (lastdepth)
-		lastindex = i + 2;
+
+	check_gas_change_events(dive, pi);
+
+	for (cyl = 0; cyl < MAX_CYLINDERS; cyl++) /* initialize the start pressures */
+		track_pr[cyl] = pr_track_alloc(dive->cylinder[cyl].start.mbar, -1);
+	current = track_pr[pi->entry[2].cylinderindex];
+	for (i = 0; i < nr_samples; i++) {
+		entry = pi->entry + i + 2;
+
+		entry->same_cylinder = entry->cylinderindex == cylinderindex;
+		cylinderindex = entry->cylinderindex;
+
+		/* track the segments per cylinder and their pressure/time integral */
+		if (!entry->same_cylinder) {
+			current->end = SENSOR_PRESSURE(entry-1);
+			current->t_end = (entry-1)->sec;
+			current = pr_track_alloc(SENSOR_PRESSURE(entry), entry->sec);
+			track_pr[cylinderindex] = list_add(track_pr[cylinderindex], current);
+		} else { /* same cylinder */
+			if ((!SENSOR_PRESSURE(entry) && SENSOR_PRESSURE(entry-1)) ||
+				(SENSOR_PRESSURE(entry) && !SENSOR_PRESSURE(entry-1))) {
+				/* transmitter changed its working status */
+				current->end = SENSOR_PRESSURE(entry-1);
+				current->t_end = (entry-1)->sec;
+				current = pr_track_alloc(SENSOR_PRESSURE(entry), entry->sec);
+				track_pr[cylinderindex] =
+					list_add(track_pr[cylinderindex], current);
+			}
+		}
+		/* finally, do the discrete integration to get the SAC rate equivalent */
+		current->pressure_time += (entry->sec - (entry-1)->sec) *
+						(1 + entry->depth / 10000.0);
+		missing_pr |= !SENSOR_PRESSURE(entry);
+	}
+
+	if (entry)
+		current->t_end = entry->sec;
+
+	for (cyl = 0; cyl < MAX_CYLINDERS; cyl++) { /* initialize the end pressures */
+		int pr = dive->cylinder[cyl].end.mbar;
+		if (pr && track_pr[cyl]) {
+			pr_track = list_last(track_pr[cyl]);
+			pr_track->end = pr;
+		}
+	}
 	/* Fill in the last two entries with empty values but valid times */
-	i = dive->samples + 2;
+	i = nr_samples + 2;
 	pi->entry[i].sec = sec + 20;
 	pi->entry[i+1].sec = sec + 40;
-
 	pi->nr = lastindex+1;
 	pi->maxtime = pi->entry[lastindex].sec;
 
-	pi->minpressure = dive->cylinder[0].end.mbar;
+	pi->endpressure = pi->minpressure = dive->cylinder[0].end.mbar;
 	pi->maxpressure = dive->cylinder[0].start.mbar;
 
 	pi->meandepth = dive->meandepth.mm;
 
+	if (missing_pr) {
+		fill_missing_tank_pressures(dive, pi, track_pr);
+	}
+	for (cyl = 0; cyl < MAX_CYLINDERS; cyl++)
+		list_free(track_pr[cyl]);
 	return analyze_plot_info(pi);
 }
 
-void plot(struct graphics_context *gc, int w, int h, struct dive *dive)
+void plot(struct graphics_context *gc, cairo_rectangle_int_t *drawing_area, struct dive *dive)
 {
-	double topx, topy;
-	struct plot_info *pi = create_plot_info(dive);
+	struct plot_info *pi;
+	static struct sample fake[4];
+	struct sample *sample = dive->sample;
+	int nr = dive->samples;
+
+	if (!nr) {
+		int duration = dive->duration.seconds;
+		int maxdepth = dive->maxdepth.mm;
+		sample = fake;
+		fake[1].time.seconds = duration * 0.05;
+		fake[1].depth.mm = maxdepth;
+		fake[2].time.seconds = duration * 0.95;
+		fake[2].depth.mm = maxdepth;
+		fake[3].time.seconds = duration * 1.00;
+		nr = 4;
+	}
+
+	pi = create_plot_info(dive, nr, sample);
 
-	topx = w / 20.0;
-	topy = h / 20.0;
-	cairo_translate(gc->cr, topx, topy);
+	cairo_translate(gc->cr, drawing_area->x, drawing_area->y);
 	cairo_set_line_width(gc->cr, 2);
 	cairo_set_line_cap(gc->cr, CAIRO_LINE_CAP_ROUND);
 	cairo_set_line_join(gc->cr, CAIRO_LINE_JOIN_ROUND);
@@ -733,8 +1121,8 @@ void plot(struct graphics_context *gc, int w, int h, struct dive *dive)
 	 *
 	 * Snif. What a pity.
 	 */
-	gc->maxx = (w - 2*topx);
-	gc->maxy = (h - 2*topy);
+	gc->maxx = (drawing_area->width - 2*drawing_area->x);
+	gc->maxy = (drawing_area->height - 2*drawing_area->y);
 
 	/* Temperature profile */
 	plot_temperature_profile(gc, pi);