X-Git-Url: http://git.tdb.fi/?p=ext%2Fsubsurface.git;a=blobdiff_plain;f=profile.c;h=0039867efc29355737294cb1ac02a0cb85743ce6;hp=1d4cabc084a377cd6ede725244fdfedcc1ac6fc1;hb=HEAD;hpb=e276b0602bf9b5953f237e67663ee0d3d8d1163b

diff --git a/profile.c b/profile.c
index 1d4cabc..0039867 100644
--- a/profile.c
+++ b/profile.c
@@ -1,5 +1,5 @@
 /* profile.c */
-/* creates all the necessary data for drawing the dive profile 
+/* creates all the necessary data for drawing the dive profile
  * uses cairo to draw it
  */
 #include <stdio.h>
@@ -11,23 +11,31 @@
 #include "dive.h"
 #include "display.h"
 #include "divelist.h"
+#include "color.h"
 
 int selected_dive = 0;
+char zoomed_plot = 0;
 
 typedef enum { STABLE, SLOW, MODERATE, FAST, CRAZY } velocity_t;
+
 /* Plot info with smoothing, velocity indication
  * and one-, two- and three-minute minimums and maximums */
 struct plot_info {
 	int nr;
 	int maxtime;
 	int meandepth, maxdepth;
-	int minpressure, maxpressure;
+	int maxpressure;
 	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];
@@ -36,14 +44,75 @@ struct plot_info {
 	} entry[];
 };
 
-/* convert velocity to colors */
-typedef struct { double r, g, b; } rgb_t;
-static const rgb_t rgb[] = {
-	[STABLE]   = {0.0, 0.4, 0.0},
-	[SLOW]     = {0.4, 0.8, 0.0},
-	[MODERATE] = {0.8, 0.8, 0.0},
-	[FAST]     = {0.8, 0.5, 0.0},
-	[CRAZY]    = {1.0, 0.0, 0.0},
+#define SENSOR_PR 0
+#define INTERPOLATED_PR 1
+#define SENSOR_PRESSURE(_entry) (_entry)->pressure[SENSOR_PR]
+#define INTERPOLATED_PRESSURE(_entry) (_entry)->pressure[INTERPOLATED_PR]
+#define GET_PRESSURE(_entry) (SENSOR_PRESSURE(_entry) ? : INTERPOLATED_PRESSURE(_entry))
+
+#define SAC_COLORS_START_IDX SAC_1
+#define SAC_COLORS 9
+#define VELOCITY_COLORS_START_IDX VELO_STABLE
+#define VELOCITY_COLORS 5
+
+typedef enum {
+	/* SAC colors. Order is important, the SAC_COLORS_START_IDX define above. */
+	SAC_1, SAC_2, SAC_3, SAC_4, SAC_5, SAC_6, SAC_7, SAC_8, SAC_9,
+
+	/* Velocity colors.  Order is still important, ref VELOCITY_COLORS_START_IDX. */
+	VELO_STABLE, VELO_SLOW, VELO_MODERATE, VELO_FAST, VELO_CRAZY,
+
+	/* Other colors */
+	TEXT_BACKGROUND, ALERT_BG, ALERT_FG, EVENTS, SAMPLE_DEEP, SAMPLE_SHALLOW,
+	SMOOTHED, MINUTE, TIME_GRID, TIME_TEXT, DEPTH_GRID, MEAN_DEPTH, DEPTH_TOP,
+	DEPTH_BOTTOM, TEMP_TEXT, TEMP_PLOT, SAC_DEFAULT, BOUNDING_BOX, PRESSURE_TEXT, BACKGROUND
+} color_indice_t;
+
+typedef struct {
+	/* media[0] is screen, and media[1] is printer */
+	struct rgba {
+		double r,g,b,a;
+	} media[2];
+} color_t;
+
+/* [color indice] = {{screen color, printer color}} */
+static const color_t profile_color[] = {
+	[SAC_1]           = {{FUNGREEN1, BLACK1_LOW_TRANS}},
+	[SAC_2]           = {{APPLE1, BLACK1_LOW_TRANS}},
+	[SAC_3]           = {{ATLANTIS1, BLACK1_LOW_TRANS}},
+	[SAC_4]           = {{ATLANTIS2, BLACK1_LOW_TRANS}},
+	[SAC_5]           = {{EARLSGREEN1, BLACK1_LOW_TRANS}},
+	[SAC_6]           = {{HOKEYPOKEY1, BLACK1_LOW_TRANS}},
+	[SAC_7]           = {{TUSCANY1, BLACK1_LOW_TRANS}},
+	[SAC_8]           = {{CINNABAR1, BLACK1_LOW_TRANS}},
+	[SAC_9]           = {{REDORANGE1, BLACK1_LOW_TRANS}},
+
+	[VELO_STABLE]     = {{CAMARONE1, BLACK1_LOW_TRANS}},
+	[VELO_SLOW]       = {{LIMENADE1, BLACK1_LOW_TRANS}},
+	[VELO_MODERATE]   = {{RIOGRANDE1, BLACK1_LOW_TRANS}},
+	[VELO_FAST]       = {{PIRATEGOLD1, BLACK1_LOW_TRANS}},
+	[VELO_CRAZY]      = {{RED1, BLACK1_LOW_TRANS}},
+
+	[TEXT_BACKGROUND] = {{CONCRETE1_LOWER_TRANS, WHITE1}},
+	[ALERT_BG]        = {{BROOM1_LOWER_TRANS, BLACK1_LOW_TRANS}},
+	[ALERT_FG]        = {{BLACK1_LOW_TRANS, BLACK1_LOW_TRANS}},
+	[EVENTS]          = {{REDORANGE1, BLACK1_LOW_TRANS}},
+	[SAMPLE_DEEP]     = {{PERSIANRED1, BLACK1_LOW_TRANS}},
+	[SAMPLE_SHALLOW]  = {{PERSIANRED1, BLACK1_LOW_TRANS}},
+	[SMOOTHED]        = {{REDORANGE1_HIGH_TRANS, BLACK1_LOW_TRANS}},
+	[MINUTE]          = {{MEDIUMREDVIOLET1_HIGHER_TRANS, BLACK1_LOW_TRANS}},
+	[TIME_GRID]       = {{WHITE1, TUNDORA1_MED_TRANS}},
+	[TIME_TEXT]       = {{FORESTGREEN1, BLACK1_LOW_TRANS}},
+	[DEPTH_GRID]      = {{WHITE1, TUNDORA1_MED_TRANS}},
+	[MEAN_DEPTH]      = {{REDORANGE1_MED_TRANS, BLACK1_LOW_TRANS}},
+	[DEPTH_BOTTOM]    = {{GOVERNORBAY1_MED_TRANS, TUNDORA1_MED_TRANS}},
+	[DEPTH_TOP]       = {{MERCURY1_MED_TRANS, WHITE1_MED_TRANS}},
+	[TEMP_TEXT]       = {{GOVERNORBAY2, BLACK1_LOW_TRANS}},
+	[TEMP_PLOT]       = {{ROYALBLUE2_LOW_TRANS, BLACK1_LOW_TRANS}},
+	[SAC_DEFAULT]     = {{WHITE1, BLACK1_LOW_TRANS}},
+	[BOUNDING_BOX]    = {{WHITE1, BLACK1_LOW_TRANS}},
+	[PRESSURE_TEXT]   = {{KILLARNEY1, BLACK1_LOW_TRANS}},
+	[BACKGROUND]      = {{SPRINGWOOD1, BLACK1_LOW_TRANS}},
 };
 
 #define plot_info_size(nr) (sizeof(struct plot_info) + (nr)*sizeof(struct plot_data))
@@ -63,51 +132,94 @@ static void line_to(struct graphics_context *gc, double x, double y)
 	cairo_line_to(gc->cr, SCALE(gc, x, y));
 }
 
-static void set_source_rgba(struct graphics_context *gc, double r, double g, double b, double a)
+static void set_source_rgba(struct graphics_context *gc, color_indice_t c)
 {
-	if (gc->printer) {
-		/* Black is white and white is black */
-		double sum = r+g+b;
-		if (sum > 2)
-			r = g = b = 0;
-		else if (sum < 1)
-			r = g = b = 1;
-	}
+	const color_t *col = &profile_color[c];
+	struct rgba rgb = col->media[gc->printer];
+	double r = rgb.r;
+	double g = rgb.g;
+	double b = rgb.b;
+	double a = rgb.a;
+
 	cairo_set_source_rgba(gc->cr, r, g, b, a);
 }
 
-void set_source_rgb(struct graphics_context *gc, double r, double g, double b)
+void init_profile_background(struct graphics_context *gc)
 {
-	set_source_rgba(gc, r, g, b, 1);
+	set_source_rgba(gc, BACKGROUND);
+}
+
+void pattern_add_color_stop_rgba(struct graphics_context *gc, cairo_pattern_t *pat, double o, color_indice_t c)
+{
+	const color_t *col = &profile_color[c];
+	struct rgba rgb = col->media[gc->printer];
+	cairo_pattern_add_color_stop_rgba(pat, o, rgb.r, rgb.g, rgb.b, rgb.a);
 }
 
 #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"
+		"    maxpressure:%d mintemp:%d maxtemp:%d\n",
+		pi->nr, pi->maxtime, pi->meandepth, pi->maxdepth,
+		pi->maxpressure, 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"
+			"                time:%d:%02d 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].sec / 60, pi->entry[i].sec % 60,
+			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
  * 30 minutes or 90 ft, just so that small dives show
- * up as such.
- * we also need to add 180 seconds at the end so the min/max
+ * up as such unless zoom is enabled.
+ * We also need to add 180 seconds at the end so the min/max
  * plots correctly
  */
 static int get_maxtime(struct plot_info *pi)
 {
 	int seconds = pi->maxtime;
-	/* min 30 minutes, rounded up to 5 minutes, with at least 2.5 minutes to spare */
-	return MAX(30*60, ROUND_UP(seconds+150, 60*5));
+	if (zoomed_plot) {
+		/* Rounded up to one minute, with at least 2.5 minutes to
+		 * spare.
+		 * For dive times shorter than 10 minutes, we use seconds/4 to
+		 * calculate the space dynamically.
+		 * This is seamless since 600/4 = 150.
+		 */
+		if ( seconds < 600 )
+			return ROUND_UP(seconds+seconds/4, 60);
+		else
+			return ROUND_UP(seconds+150, 60);
+	} else {
+		/* min 30 minutes, rounded up to 5 minutes, with at least 2.5 minutes to spare */
+		return MAX(30*60, ROUND_UP(seconds+150, 60*5));
+	}
 }
 
 static int get_maxdepth(struct plot_info *pi)
 {
 	unsigned mm = pi->maxdepth;
-	/* Minimum 30m, rounded up to 10m, with at least 3m to spare */
-	return MAX(30000, ROUND_UP(mm+3000, 10000));
+	if (zoomed_plot) {
+		/* Rounded up to 10m, with at least 3m to spare */
+		return ROUND_UP(mm+3000, 10000);
+	} else {
+		/* Minimum 30m, rounded up to 10m, with at least 3m to spare */
+		return MAX(30000, ROUND_UP(mm+3000, 10000));
+	}
 }
 
 typedef struct {
 	int size;
-	double r,g,b;
+	color_indice_t color;
 	double hpos, vpos;
 } text_render_options_t;
 
@@ -143,53 +255,146 @@ static void plot_text(struct graphics_context *gc, const text_render_options_t *
 	cairo_rel_move_to(cr, dx, dy);
 
 	cairo_text_path(cr, buffer);
-	set_source_rgb(gc, 0, 0, 0);
+	set_source_rgba(gc, TEXT_BACKGROUND);
 	cairo_stroke(cr);
 
 	move_to(gc, x, y);
 	cairo_rel_move_to(cr, dx, dy);
 
-	set_source_rgb(gc, tro->r, tro->g, tro->b);
+	set_source_rgba(gc, tro->color);
 	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->depth;
+	}
+	/* draw a little tirangular marker and attach tooltip */
+	x = SCALEX(gc, event->time.seconds);
+	y = SCALEY(gc, depth);
+	set_source_rgba(gc, ALERT_BG);
+	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, ALERT_FG);
+	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)
+{
+	static const text_render_options_t tro = {14, EVENTS, CENTER, TOP};
+	struct event *event = dive->events;
+
+	if (gc->printer)
+		return;
+
+	while (event) {
+		plot_one_event(gc, pi, event, &tro);
+		event = event->next;
+	}
+}
+
 static void render_depth_sample(struct graphics_context *gc, struct plot_data *entry, const text_render_options_t *tro)
 {
-	int sec = entry->sec;
-	depth_t depth = { entry->val };
-	const char *fmt;
+	int sec = entry->sec, decimals;
 	double d;
 
-	switch (output_units.length) {
-	case METERS:
-		d = depth.mm / 1000.0;
-		fmt = "%.1f";
-		break;
-	case FEET:
-		d = to_feet(depth);
-		fmt = "%.0f";
-		break;
-	}
-	plot_text(gc, tro, sec, depth.mm, fmt, d);
+	d = get_depth_units(entry->depth, &decimals, NULL);
+
+	plot_text(gc, tro, sec, entry->depth, "%.*f", decimals, d);
 }
 
 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};
+	static const text_render_options_t deep = {14, SAMPLE_DEEP, CENTER, TOP};
+	static const text_render_options_t shallow = {14, SAMPLE_SHALLOW, 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;
 	}
 }
 
@@ -212,7 +417,7 @@ static void plot_smoothed_profile(struct graphics_context *gc, struct plot_info
 	int i;
 	struct plot_data *entry = pi->entry;
 
-	cairo_set_source_rgba(gc->cr, 1, 0.2, 0.2, 0.20);
+	set_source_rgba(gc, SMOOTHED);
 	move_to(gc, entry->sec, entry->smoothed);
 	for (i = 1; i < pi->nr; i++) {
 		entry++;
@@ -222,19 +427,19 @@ static void plot_smoothed_profile(struct graphics_context *gc, struct plot_info
 }
 
 static void plot_minmax_profile_minute(struct graphics_context *gc, struct plot_info *pi,
-				int index, double a)
+				int index)
 {
 	int i;
 	struct plot_data *entry = pi->entry;
 
-	cairo_set_source_rgba(gc->cr, 1, 0.2, 1, a);
-	move_to(gc, entry->sec, entry->min[index]->val);
+	set_source_rgba(gc, MINUTE);
+	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);
@@ -245,33 +450,60 @@ static void plot_minmax_profile(struct graphics_context *gc, struct plot_info *p
 {
 	if (gc->printer)
 		return;
-	plot_minmax_profile_minute(gc, pi, 2, 0.1);
-	plot_minmax_profile_minute(gc, pi, 1, 0.1);
-	plot_minmax_profile_minute(gc, pi, 0, 0.1);
+	plot_minmax_profile_minute(gc, pi, 2);
+	plot_minmax_profile_minute(gc, pi, 1);
+	plot_minmax_profile_minute(gc, pi, 0);
 }
 
 static void plot_depth_profile(struct graphics_context *gc, struct plot_info *pi)
 {
-	int i;
+	int i, incr;
 	cairo_t *cr = gc->cr;
-	int ends, sec, depth;
-	int *secs;
-	int *depths;
+	int sec, depth;
 	struct plot_data *entry;
 	int maxtime, maxdepth, marker;
+	int increments[8] = { 10, 20, 30, 60, 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 10 seconds, but no more than 12 markers.
+	 * We start out with 10 seconds and increment up to 30 minutes,
+	 * depending on the dive time.
+	 * 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 < 8)
+		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, TIME_GRID);
+	cairo_set_line_width(gc->cr, 2);
+
+	for (i = incr; i < maxtime; i += incr) {
 		move_to(gc, i, 0);
 		line_to(gc, i, 1);
 	}
+	cairo_stroke(cr);
 
+	/* now the text on the time markers */
+	text_render_options_t tro = {10, TIME_TEXT, CENTER, TOP};
+	if (maxtime < 600) {
+		/* Be a bit more verbose with shorter dives */
+		for (i = incr; i < maxtime; i += incr)
+			plot_text(gc, &tro, i, 1, "%02d:%02d", i/60, i%60);
+	} else {
+		/* Only render the time on every second marker for normal dives */
+		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;
 	gc->topy = 0; gc->bottomy = maxdepth;
@@ -280,7 +512,7 @@ static void plot_depth_profile(struct graphics_context *gc, struct plot_info *pi
 	case FEET: marker = 9144; break;	/* 30 ft */
 	}
 
-	set_source_rgba(gc, 1, 1, 1, 0.5);
+	set_source_rgba(gc, DEPTH_GRID);
 	for (i = marker; i < maxdepth; i += marker) {
 		move_to(gc, 0, i);
 		line_to(gc, 1, i);
@@ -288,10 +520,12 @@ static void plot_depth_profile(struct graphics_context *gc, struct plot_info *pi
 	cairo_stroke(cr);
 
 	/* Show mean depth */
-	set_source_rgba(gc, 1, 0.2, 0.2, 0.40);
-	move_to(gc, 0, pi->meandepth);
-	line_to(gc, 1, pi->meandepth);
-	cairo_stroke(cr);
+	if (! gc->printer) {
+		set_source_rgba(gc, MEAN_DEPTH);
+		move_to(gc, 0, pi->meandepth);
+		line_to(gc, 1, pi->meandepth);
+		cairo_stroke(cr);
+	}
 
 	gc->leftx = 0; gc->rightx = maxtime;
 
@@ -304,49 +538,40 @@ static void plot_depth_profile(struct graphics_context *gc, struct plot_info *pi
 		plot_minmax_profile(gc, pi);
 	}
 
+	/* Do the depth profile for the neat fill */
+	gc->topy = 0; gc->bottomy = maxdepth;
+
+	cairo_pattern_t *pat;
+	pat = cairo_pattern_create_linear (0.0, 0.0,  0.0, 256.0);
+	pattern_add_color_stop_rgba (gc, pat, 1, DEPTH_BOTTOM);
+	pattern_add_color_stop_rgba (gc, pat, 0, DEPTH_TOP);
+
+	cairo_set_source(gc->cr, pat);
+	cairo_pattern_destroy(pat);
+	cairo_set_line_width(gc->cr, 2);
+
+	entry = pi->entry;
+	move_to(gc, 0, 0);
+	for (i = 0; i < pi->nr; i++, entry++)
+		line_to(gc, entry->sec, entry->depth);
+	cairo_close_path(gc->cr);
+
+	cairo_fill(gc->cr);
+
+	/* Now do it again for the velocity colors */
 	entry = pi->entry;
-	set_source_rgba(gc, 1, 0.2, 0.2, 0.80);
-	secs = (int *) malloc(sizeof(int) * pi->nr);
-	depths = (int *) malloc(sizeof(int) * pi->nr);
-	secs[0] = entry->sec;
-	depths[0] = entry->val;
 	for (i = 1; i < pi->nr; i++) {
 		entry++;
 		sec = entry->sec;
-		if (sec <= maxtime || entry->val > 0) {
-			/* we want to draw the segments in different colors
-			 * representing the vertical velocity, so we need to
-			 * chop this into short segments */
-			rgb_t color = rgb[entry->velocity];
-			depth = entry->val;
-			set_source_rgb(gc, color.r, color.g, color.b);
-			move_to(gc, secs[i-1], depths[i-1]);
-			line_to(gc, sec, depth);
-			cairo_stroke(cr);
-			ends = i;
-		}
-		secs[i] = sec;
-		depths[i] = depth;
-	}
-	move_to(gc, secs[ends], depths[ends]);
-	gc->topy = 0; gc->bottomy = 1.0;
-	line_to(gc, secs[ends], 0);
-	line_to(gc, secs[0], 0);
-	cairo_close_path(cr);
-	set_source_rgba(gc, 1, 0.2, 0.2, 0.80);
-	cairo_stroke(cr);
-	/* now do it again for the neat fill */
-	gc->topy = 0; gc->bottomy = maxdepth;
-	set_source_rgba(gc, 1, 0.2, 0.2, 0.20);
-	move_to(gc, secs[0], depths[0]);
-	for (i = 1; i <= ends; i++) {
-		line_to(gc, secs[i],depths[i]);
+		/* we want to draw the segments in different colors
+		 * representing the vertical velocity, so we need to
+		 * chop this into short segments */
+		depth = entry->depth;
+		set_source_rgba(gc, VELOCITY_COLORS_START_IDX + entry->velocity);
+		move_to(gc, entry[-1].sec, entry[-1].depth);
+		line_to(gc, sec, depth);
+		cairo_stroke(cr);
 	}
-	gc->topy = 0; gc->bottomy = 1.0;
-	line_to(gc, secs[ends], 0);
-	line_to(gc, secs[0], 0);
-	cairo_close_path(gc->cr);
-	cairo_fill(gc->cr);
 }
 
 static int setup_temperature_limits(struct graphics_context *gc, struct plot_info *pi)
@@ -375,25 +600,19 @@ 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 };
+	static const text_render_options_t tro = {12, TEMP_TEXT, LEFT, TOP};
 
-	if (output_units.temperature == FAHRENHEIT) {
-		deg = to_F(temperature);
-		unit = "F";
-	} else {
-		deg = to_C(temperature);
-		unit = "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)
 {
 	int i;
-	int last = 0, sec = 0;
+	int last = -300, sec = 0;
 	int last_temperature = 0, last_printed_temp = 0;
 
 	if (!setup_temperature_limits(gc, pi))
@@ -407,14 +626,23 @@ static void plot_temperature_text(struct graphics_context *gc, struct plot_info
 			continue;
 		last_temperature = mkelvin;
 		sec = entry->sec;
-		if (sec < last + 300)
+		/* don't print a temperature
+		 * if it's been less than 5min and less than a 2K change OR
+		 * if it's been less than 2min OR if the change from the
+		 * last print is less than .4K (and therefore less than 1F */
+		if (((sec < last + 300) && (abs(mkelvin - last_printed_temp) < 2000)) ||
+			(sec < last + 120) ||
+			(abs(mkelvin - last_printed_temp) < 400))
 			continue;
 		last = sec;
 		plot_single_temp_text(gc,sec,mkelvin);
 		last_printed_temp = mkelvin;
 	}
-	/* it would be nice to print the end temperature, if it's different */
-	if (abs(last_temperature - last_printed_temp) > 500)
+	/* it would be nice to print the end temperature, if it's
+	 * different or if the last temperature print has been more
+	 * than a quarter of the dive back */
+	if ((abs(last_temperature - last_printed_temp) > 500) ||
+		((double)last / (double)sec < 0.75))
 		plot_single_temp_text(gc, sec, last_temperature);
 }
 
@@ -427,7 +655,8 @@ static void plot_temperature_profile(struct graphics_context *gc, struct plot_in
 	if (!setup_temperature_limits(gc, pi))
 		return;
 
-	set_source_rgba(gc, 0.2, 0.2, 1.0, 0.8);
+	cairo_set_line_width(gc->cr, 2);
+	set_source_rgba(gc, TEMP_PLOT);
 	for (i = 0; i < pi->nr; i++) {
 		struct plot_data *entry = pi->entry + i;
 		int mkelvin = entry->temperature;
@@ -456,63 +685,162 @@ 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)
+/* set the color for the pressure plot according to temporary sac rate
+ * as compared to avg_sac; the calculation simply maps the delta between
+ * sac and avg_sac to indexes 0 .. (SAC_COLORS - 1) with everything
+ * more than 6000 ml/min below avg_sac mapped to 0 */
+
+static void set_sac_color(struct graphics_context *gc, int sac, int avg_sac)
+{
+	int sac_index = 0;
+	int delta = sac - avg_sac + 7000;
+
+	if (!gc->printer) {
+		sac_index = delta / 2000;
+		if (sac_index < 0)
+			sac_index = 0;
+		if (sac_index > SAC_COLORS - 1)
+			sac_index = SAC_COLORS - 1;
+		set_source_rgba(gc, SAC_COLORS_START_IDX + sac_index);
+	} else {
+		set_source_rgba(gc, SAC_DEFAULT);
+	}
+}
+
+/* calculate the current SAC in ml/min and convert to int */
+#define GET_LOCAL_SAC(_entry1, _entry2, _dive)	(int)				\
+	((GET_PRESSURE((_entry1)) - GET_PRESSURE((_entry2))) *			\
+		(_dive)->cylinder[(_entry1)->cylinderindex].type.size.mliter /	\
+		(((_entry2)->sec - (_entry1)->sec) / 60.0) /			\
+		(1 + ((_entry1)->depth + (_entry2)->depth) / 20000.0) /		\
+		1000.0)
+
+#define SAC_WINDOW 45	/* sliding window in seconds for current SAC calculation */
+
+static void plot_cylinder_pressure(struct graphics_context *gc, struct plot_info *pi,
+				struct dive *dive)
 {
 	int i;
+	int last = -1;
+	int lift_pen = FALSE;
+	int first_plot = TRUE;
+	int sac = 0;
+	struct plot_data *last_entry = NULL;
 
 	if (!get_cylinder_pressure_range(gc, pi))
 		return;
 
-	cairo_set_source_rgba(gc->cr, 0.2, 1.0, 0.2, 0.80);
+	cairo_set_line_width(gc->cr, 2);
 
-	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 = GET_PRESSURE(entry);
+		if (!entry->same_cylinder) {
+			lift_pen = TRUE;
+			last_entry = NULL;
+		}
+		if (!mbar) {
+			lift_pen = TRUE;
 			continue;
-		line_to(gc, entry->sec, mbar);
+		}
+		if (!last_entry) {
+			last = i;
+			last_entry = entry;
+			sac = GET_LOCAL_SAC(entry, pi->entry + i + 1, dive);
+		} else {
+			int j;
+			sac = 0;
+			for (j = last; j < i; j++)
+				sac += GET_LOCAL_SAC(pi->entry + j, pi->entry + j + 1, dive);
+			sac /= (i - last);
+			if (entry->sec - last_entry->sec >= SAC_WINDOW) {
+				last++;
+				last_entry = pi->entry + last;
+			}
+		}
+		set_sac_color(gc, sac, dive->sac);
+		if (lift_pen) {
+			if (!first_plot && entry->same_cylinder) {
+				/* if we have a previous event from the same tank,
+				 * draw at least a short line */
+				int prev_pr;
+				prev_pr = GET_PRESSURE(entry - 1);
+				move_to(gc, (entry-1)->sec, prev_pr);
+				line_to(gc, entry->sec, mbar);
+			} else {
+				first_plot = FALSE;
+				move_to(gc, entry->sec, mbar);
+			}
+			lift_pen = FALSE;
+		} else {
+			line_to(gc, entry->sec, mbar);
+		}
+		cairo_stroke(gc->cr);
+		move_to(gc, entry->sec, mbar);
 	}
-	line_to(gc, pi->maxtime, pi->minpressure);
-	cairo_stroke(gc->cr);
 }
 
-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, PRESSURE_TEXT, 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;
 
-		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);
+	/* only loop over the actual events from the dive computer
+	 * plus the second synthetic event at the start (to make sure
+	 * we get "time=0" right)
+	 * sadly with a recent change that first entry may no longer
+	 * have any pressure reading - in that case just grab the
+	 * pressure from the second entry */
+	if (GET_PRESSURE(pi->entry + 1) == 0 && GET_PRESSURE(pi->entry + 2) !=0)
+		INTERPOLATED_PRESSURE(pi->entry + 1) = GET_PRESSURE(pi->entry + 2);
+	for (i = 1; i < pi->nr; i++) {
+		entry = pi->entry + i;
+
+		if (!entry->same_cylinder) {
+			cyl = entry->cylinderindex;
+			if (!seen_cyl[cyl]) {
+				mbar = GET_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] = GET_PRESSURE(entry - 1);
+				last_time[cyl] = (entry - 1)->sec;
+			}
+		}
+	}
+	cyl = entry->cylinderindex;
+	if (GET_PRESSURE(entry))
+		last_pressure[cyl] = GET_PRESSURE(entry);
+	last_time[cyl] = entry->sec;
+
+	for (cyl = 0; cyl < MAX_CYLINDERS; cyl++) {
+		if (last_time[cyl]) {
+			plot_pressure_value(gc, last_pressure[cyl], last_time[cyl], CENTER, TOP);
+		}
 	}
 }
 
@@ -533,17 +861,17 @@ 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;
@@ -571,7 +899,7 @@ static velocity_t velocity(int speed)
 	else if (speed < -25) /* -5ft/min */
 		v = SLOW;
 	else if (speed < 25) /* very hard to find data, but it appears that the recommendations
-				for descent are usually about 2x ascent rate; still, we want 
+				for descent are usually about 2x ascent rate; still, we want
 				stable to mean stable */
 		v = STABLE;
 	else if (speed < 152) /* between 5 and 30ft/min is considered slow */
@@ -593,12 +921,10 @@ 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 = GET_PRESSURE(entry);
 		int temperature = entry->temperature;
 
 		if (pressure) {
-			if (!pi->minpressure || pressure < pi->minpressure)
-				pi->minpressure = pressure;
 			if (pressure > pi->maxpressure)
 				pi->maxpressure = pressure;
 		}
@@ -612,24 +938,24 @@ static struct plot_info *analyze_plot_info(struct plot_info *pi)
 	}
 
 	/* Smoothing function: 5-point triangular smooth */
-	for (i = 2; i < nr-1; i++) {
+	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 < 30 && entry->velocity < FAST) { 
+			if (entry[0].sec - entry[-1].sec < 15 && entry->velocity < FAST) {
 				int past = -2;
-				while (pi->entry <= entry-past && entry[0].sec - entry[past].sec < 30)
+				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
@@ -641,10 +967,222 @@ static struct plot_info *analyze_plot_info(struct plot_info *pi)
 		struct plot_data *entry = pi->entry +i;
 		analyze_plot_info_minmax(entry, pi->entry, pi->entry+nr);
 	}
-	
+
 	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 dump_pr_track(pr_track_t **track_pr)
+{
+	int cyl;
+	pr_track_t *list;
+
+	for (cyl = 0; cyl < MAX_CYLINDERS; cyl++) {
+		list = track_pr[cyl];
+		while (list) {
+			printf("cyl%d: start %d end %d t_start %d t_end %d pt %6.3f\n", cyl,
+				list->start, list->end, list->t_start, list->t_end, list->pressure_time);
+			list = list->next;
+		}
+	}
+}
+
+static void fill_missing_tank_pressures(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];
+
+	if (0) {
+		/* another great debugging tool */
+		dump_pr_track(track_pr);
+	}
+	for (cyl = 0; cyl < MAX_CYLINDERS; cyl++) {
+		cur_pr[cyl] = track_pr[cyl]->start;
+	}
+
+	/* The first two are "fillers", but in case we don't have a sample
+	 * at time 0 we need to process the second of them here */
+	for (i = 1; 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;
+				if (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 */
+					INTERPOLATED_PRESSURE(entry) = cur_pr[entry->cylinderindex];
+					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 + (entry-1)->depth) / 20000.0);
+				INTERPOLATED_PRESSURE(entry) =
+					cur_pr[entry->cylinderindex] + cur_pt * magic + 0.5;
+				cur_pr[entry->cylinderindex] = INTERPOLATED_PRESSURE(entry);
+			} else
+				INTERPOLATED_PRESSURE(entry) = cur_pr[entry->cylinderindex];
+		}
+	}
+}
+
+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);
+}
+
+/* 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
  *
@@ -652,65 +1190,218 @@ 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;
-	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 < 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;
-
-		sec = entry->sec = sample->time.seconds;
-		depth = entry->val = sample->depth.mm;
-		entry->pressure = sample->cylinderpressure.mbar;
+		int delay = 0;
+		struct sample *sample = dive_sample+i;
+
+		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 */
+			if (ev->time.seconds == sample->time.seconds - 1) {
+				entry->sec = ev->time.seconds - 1;
+				(entry+1)->sec = ev->time.seconds;
+			} else {
+				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;
 	}
-	if (lastdepth)
-		lastindex = i + 2;
-	/* Fill in the last two entries with empty values but valid times */
-	i = dive->samples + 2;
+	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 = nr_samples + pi_idx - 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 + 1; i++) {
+		entry = pi->entry + i + 1;
+
+		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 + (entry-1)->depth) / 20000.0);
+		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
+	 * without creating a false cylinder change event */
+	i = nr + 2;
 	pi->entry[i].sec = sec + 20;
+	pi->entry[i].same_cylinder = 1;
+	pi->entry[i].cylinderindex = pi->entry[i-1].cylinderindex;
+	INTERPOLATED_PRESSURE(pi->entry + i) = GET_PRESSURE(pi->entry + i - 1);
 	pi->entry[i+1].sec = sec + 40;
-
+	pi->entry[i+1].same_cylinder = 1;
+	pi->entry[i+1].cylinderindex = pi->entry[i-1].cylinderindex;
+	INTERPOLATED_PRESSURE(pi->entry + i + 1) = GET_PRESSURE(pi->entry + i - 1);
+	/* the number of actual entries - some computers have lots of
+	 * depth 0 samples at the end of a dive, we want to make sure
+	 * we have exactly one of them at the end */
 	pi->nr = lastindex+1;
+	while (pi->nr <= i+2 && pi->entry[pi->nr-1].depth > 0)
+		pi->nr++;
 	pi->maxtime = pi->entry[lastindex].sec;
 
-	pi->minpressure = dive->cylinder[0].end.mbar;
-	pi->maxpressure = dive->cylinder[0].start.mbar;
+	/* Analyze_plot_info() will do the sample max pressures,
+	 * this handles the manual pressures
+	 */
+	pi->maxpressure = 0;
+	for (cyl = 0; cyl < MAX_CYLINDERS; cyl++) {
+		unsigned int mbar = dive->cylinder[cyl].start.mbar;
+		if (mbar > pi->maxpressure)
+			pi->maxpressure = mbar;
+	}
 
 	pi->meandepth = dive->meandepth.mm;
 
+	if (missing_pr) {
+		fill_missing_tank_pressures(pi, track_pr);
+	}
+	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);
 }
 
-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) {
+		/* The dive has no samples, so create a few fake ones.  This assumes an
+		ascent/descent rate of 9 m/min, which is just below the limit for FAST. */
+		int duration = dive->duration.seconds;
+		int maxdepth = dive->maxdepth.mm;
+		int asc_desc_time = dive->maxdepth.mm*60/9000;
+		if (asc_desc_time * 2 >= duration)
+			asc_desc_time = duration / 2;
+		sample = fake;
+		fake[1].time.seconds = asc_desc_time;
+		fake[1].depth.mm = maxdepth;
+		fake[2].time.seconds = duration - asc_desc_time;
+		fake[2].depth.mm = maxdepth;
+		fake[3].time.seconds = duration * 1.00;
+		nr = 4;
+	}
 
-	topx = w / 20.0;
-	topy = h / 20.0;
-	cairo_translate(gc->cr, topx, topy);
-	cairo_set_line_width(gc->cr, 2);
+	pi = create_plot_info(dive, nr, sample);
+
+	cairo_translate(gc->cr, drawing_area->x, drawing_area->y);
+	cairo_set_line_width(gc->cr, 1);
 	cairo_set_line_cap(gc->cr, CAIRO_LINE_CAP_ROUND);
 	cairo_set_line_join(gc->cr, CAIRO_LINE_JOIN_ROUND);
 
@@ -721,17 +1412,18 @@ 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);
+
+	/* Depth profile */
+	plot_depth_profile(gc, pi);
+	plot_events(gc, pi, dive);
 
 	/* Temperature profile */
 	plot_temperature_profile(gc, pi);
 
 	/* Cylinder pressure plot */
-	plot_cylinder_pressure(gc, pi);
-
-	/* Depth profile */
-	plot_depth_profile(gc, pi);
+	plot_cylinder_pressure(gc, pi, dive);
 
 	/* Text on top of all graphs.. */
 	plot_temperature_text(gc, pi);
@@ -742,7 +1434,8 @@ void plot(struct graphics_context *gc, int w, int h, struct dive *dive)
 	gc->leftx = 0; gc->rightx = 1.0;
 	gc->topy = 0; gc->bottomy = 1.0;
 
-	set_source_rgb(gc, 1, 1, 1);
+	set_source_rgba(gc, BOUNDING_BOX);
+	cairo_set_line_width(gc->cr, 1);
 	move_to(gc, 0, 0);
 	line_to(gc, 0, 1);
 	line_to(gc, 1, 1);
@@ -750,4 +1443,5 @@ void plot(struct graphics_context *gc, int w, int h, struct dive *dive)
 	cairo_close_path(gc->cr);
 	cairo_stroke(gc->cr);
 
+	free(pi);
 }