+}
+
+/* gets both the actual start and end pressure as well as the scaling factors */
+static int get_cylinder_pressure_range(struct dive *dive, struct graphics_context *gc,
+ pressure_t *startp, pressure_t *endp)
+{
+ int i;
+ int min, max;
+
+ gc->scalex = round_seconds_up(dive->duration.seconds);
+
+ max = 0;
+ min = 5000000;
+ if (startp)
+ startp->mbar = endp->mbar = 0;
+
+ for (i = 0; i < dive->samples; i++) {
+ int mbar;
+ struct sample *sample = dive->sample + i;
+
+ /* FIXME! We only track cylinder 0 right now */
+ if (sample->cylinderindex)
+ continue;
+ mbar = sample->cylinderpressure.mbar;
+ if (!mbar)
+ continue;
+ if (mbar < min)
+ min = mbar;
+ if (mbar > max)
+ max = mbar;
+ }
+ if (startp)
+ startp->mbar = max;
+ if (endp)
+ endp->mbar = min;
+ if (!max)
+ return 0;
+ gc->scaley = max * 1.5;
+ return 1;
+}
+
+static void plot_cylinder_pressure(struct dive *dive, struct graphics_context *gc)
+{
+ int i, sec = -1;
+
+ if (!get_cylinder_pressure_range(dive, gc, NULL, NULL))
+ return;
+
+ cairo_set_source_rgba(gc->cr, 0.2, 1.0, 0.2, 0.80);
+
+ move_to(gc, 0, dive->cylinder[0].start.mbar);
+ for (i = 1; i < dive->samples; i++) {
+ int mbar;
+ struct sample *sample = dive->sample + i;
+
+ mbar = sample->cylinderpressure.mbar;
+ if (!mbar)
+ continue;
+ sec = sample->time.seconds;
+ if (sec <= dive->duration.seconds)
+ line_to(gc, sec, mbar);
+ }
+ /*
+ * We may have "surface time" events, in which case we don't go
+ * back to dive duration
+ */
+ if (sec < dive->duration.seconds)
+ line_to(gc, dive->duration.seconds, dive->cylinder[0].end.mbar);
+ cairo_stroke(gc->cr);
+}
+
+/*
+ * Return air usage (in liters).
+ */
+static double calculate_airuse(struct dive *dive)
+{
+ double airuse = 0;
+ int i;
+
+ for (i = 0; i < MAX_CYLINDERS; i++) {
+ cylinder_t *cyl = dive->cylinder + i;
+ int size = cyl->type.size.mliter;
+ double kilo_atm;
+
+ if (!size)
+ continue;
+
+ kilo_atm = (cyl->start.mbar - cyl->end.mbar) / 1013250.0;
+
+ /* Liters of air at 1 atm == milliliters at 1k atm*/
+ airuse += kilo_atm * size;
+ }
+ return airuse;
+}
+
+static void plot_info(struct dive *dive, struct graphics_context *gc)
+{
+ text_render_options_t tro = {10, 0.2, 1.0, 0.2, LEFT, TOP};
+ const double liters_per_cuft = 28.317;
+ const char *unit, *desc;
+ double airuse;
+
+ airuse = calculate_airuse(dive);
+ if (!airuse)
+ return;
+
+ /* I really need to start addign some unit setting thing */
+ switch (output_units.volume) {
+ case LITER:
+ unit = "l";
+ break;
+ case CUFT:
+ unit = "cuft";
+ airuse /= liters_per_cuft;
+ break;
+ }
+ plot_text(gc, &tro, 0.8, 0.8, "vol: %4.2f %s", airuse, unit);
+ if (dive->duration.seconds) {
+ double pressure = 1 + (dive->meandepth.mm / 10000.0);
+ double sac = airuse / pressure * 60 / dive->duration.seconds;
+ plot_text(gc, &tro, 0.8, 0.85, "SAC: %4.2f %s/min", sac, unit);
+ }
+ desc = dive->cylinder[0].type.description;
+ if (desc || dive->cylinder[0].gasmix.o2.permille) {
+ int o2 = dive->cylinder[0].gasmix.o2.permille / 10;
+ if (!desc)
+ desc = "";
+ if (!o2)
+ o2 = 21;
+ plot_text(gc, &tro, 0.8, 0.9, "%s (%d%%)", desc, o2);
+ }
+}
+
+static void plot_cylinder_pressure_text(struct dive *dive, struct graphics_context *gc)
+{
+ pressure_t startp, endp;
+
+ if (get_cylinder_pressure_range(dive, gc, &startp, &endp)) {
+ int start, end;
+ const char *unit = "bar";
+
+ switch (output_units.pressure) {
+ case PASCAL:
+ start = startp.mbar * 100;
+ end = startp.mbar * 100;
+ unit = "pascal";
+ break;
+ case BAR:
+ start = (startp.mbar + 500) / 1000;
+ end = (endp.mbar + 500) / 1000;
+ unit = "bar";
+ break;
+ case PSI:
+ start = to_PSI(startp);
+ end = to_PSI(endp);
+ unit = "psi";
+ break;
+ }
+
+ text_render_options_t tro = {10, 0.2, 1.0, 0.2, LEFT, TOP};
+ plot_text(gc, &tro, 0, startp.mbar, "%d %s", start, unit);
+ plot_text(gc, &tro, dive->duration.seconds, endp.mbar,
+ "%d %s", end, unit);
+ }
+}
+
+static void analyze_plot_info_minmax_minute(struct plot_data *entry, struct plot_data *first, struct plot_data *last, int index)
+{
+ struct plot_data *p = entry;
+ int time = entry->sec;
+ int seconds = 90*(index+1);
+ struct plot_data *min, *max;
+ int avg, nr;
+
+ /* Go back 'seconds' in time */
+ while (p > first) {
+ if (p[-1].sec < time - seconds)
+ break;
+ p--;
+ }
+
+ /* Then go forward until we hit an entry past the time */
+ min = max = p;
+ avg = p->val;
+ nr = 1;
+ while (++p < last) {
+ int val = p->val;
+ if (p->sec > time + seconds)
+ break;
+ avg += val;
+ nr ++;
+ if (val < min->val)
+ min = p;
+ if (val > max->val)
+ max = p;
+ }
+ entry->min[index] = min;
+ entry->max[index] = max;
+ entry->avg[index] = (avg + nr/2) / nr;
+}
+
+static void analyze_plot_info_minmax(struct plot_data *entry, struct plot_data *first, struct plot_data *last)
+{
+ analyze_plot_info_minmax_minute(entry, first, last, 0);
+ analyze_plot_info_minmax_minute(entry, first, last, 1);
+ analyze_plot_info_minmax_minute(entry, first, last, 2);
+}
+
+static struct plot_info *analyze_plot_info(struct plot_info *pi)
+{
+ int i;
+ int nr = pi->nr;
+
+ /* Smoothing function: 5-point triangular smooth */
+ for (i = 2; i < nr-2; i++) {
+ struct plot_data *entry = pi->entry+i;
+ int val;
+
+ val = entry[-2].val + 2*entry[-1].val + 3*entry[0].val + 2*entry[1].val + entry[2].val;
+ entry->smoothed = (val+4) / 9;
+ }
+
+ /* One-, two- and three-minute minmax data */
+ for (i = 0; i < nr; i++) {
+ struct plot_data *entry = pi->entry +i;
+ analyze_plot_info_minmax(entry, pi->entry, pi->entry+nr);
+ }
+
+ return pi;
+}
+
+/*
+ * Create a plot-info with smoothing and ranged min/max
+ *
+ * This also makes sure that we have extra empty events on both
+ * sides, so that you can do end-points without having to worry
+ * about it.
+ */
+static struct plot_info *depth_plot_info(struct dive *dive)
+{
+ int i, nr = dive->samples + 4, sec;
+ size_t alloc_size = plot_info_size(nr);
+ struct plot_info *pi;
+
+ pi = malloc(alloc_size);
+ if (!pi)
+ return pi;
+ memset(pi, 0, alloc_size);
+ pi->nr = nr;
+ sec = 0;
+ for (i = 0; i < dive->samples; i++) {
+ struct sample *sample = dive->sample+i;
+ struct plot_data *entry = pi->entry + i + 2;
+
+ sec = entry->sec = sample->time.seconds;
+ entry->val = sample->depth.mm;
+ }
+ /* Fill in the last two entries with empty values but valid times */
+ i = dive->samples + 2;
+ pi->entry[i].sec = sec + 20;
+ pi->entry[i+1].sec = sec + 40;
+
+ return analyze_plot_info(pi);
+}
+
+static void plot(struct graphics_context *gc, int w, int h, struct dive *dive)
+{
+ double topx, topy;
+ struct plot_info *pi = depth_plot_info(dive);
+
+ topx = w / 20.0;
+ topy = h / 20.0;
+ cairo_translate(gc->cr, topx, topy);
+
+ /*
+ * We can use "cairo_translate()" because that doesn't
+ * scale line width etc. But the actual scaling we need
+ * do set up ourselves..
+ *
+ * Snif. What a pity.
+ */
+ gc->maxx = (w - 2*topx);
+ gc->maxy = (h - 2*topy);
+
+ /* Cylinder pressure plot */
+ plot_cylinder_pressure(dive, gc);
+
+ /* Depth profile */
+ plot_depth_profile(dive, gc, pi);
+
+ /* Text on top of all graphs.. */
+ plot_depth_text(dive, gc, pi);
+ plot_cylinder_pressure_text(dive, gc);
+
+ /* And info box in the lower right corner.. */
+ gc->scalex = gc->scaley = 1.0;
+ plot_info(dive, gc);