+}
+
+static int get_cylinder_pressure_range(struct dive *dive, double *scalex, double *scaley)
+{
+ int i;
+ double min, max;
+
+ *scalex = round_seconds_up(dive->duration.seconds);
+
+ max = 0;
+ min = 5000;
+ for (i = 0; i < dive->samples; i++) {
+ struct sample *sample = dive->sample + i;
+ double bar;
+
+ /* FIXME! We only track cylinder 0 right now */
+ if (sample->cylinderindex)
+ continue;
+ if (!sample->cylinderpressure.mbar)
+ continue;
+ bar = sample->cylinderpressure.mbar;
+ if (bar < min)
+ min = bar;
+ if (bar > max)
+ max = bar;
+ }
+ if (!max)
+ return 0;
+ *scaley = max * 1.5;
+ return 1;
+}
+
+static void plot_cylinder_pressure(struct dive *dive, cairo_t *cr,
+ double topx, double topy, double maxx, double maxy)
+{
+ int i, sec = -1;
+ double scalex, scaley;
+
+ if (!get_cylinder_pressure_range(dive, &scalex, &scaley))
+ return;
+
+ cairo_set_source_rgba(cr, 0.2, 1.0, 0.2, 0.80);
+
+ cairo_move_to(cr, SCALE(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;
+ cairo_line_to(cr, SCALE(sec, mbar));
+ }
+ /*
+ * We may have "surface time" events, in which case we don't go
+ * back to dive duration
+ */
+ if (sec < dive->duration.seconds)
+ cairo_line_to(cr, SCALE(dive->duration.seconds, dive->cylinder[0].end.mbar));
+ cairo_stroke(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, cairo_t *cr,
+ double topx, double topy, double maxx, double maxy)
+{
+ const double liters_per_cuft = 28.317;
+ double airuse;
+
+ airuse = calculate_airuse(dive);
+ if (!airuse)
+ return;
+
+ /* I really need to start addign some unit setting thing */
+ airuse /= liters_per_cuft;
+ plot_text(cr, 1, 0, maxx*0.95, maxy*0.9, "cuft: %4.2f", airuse);
+ if (dive->duration.seconds) {
+ double pressure = 1 + (dive->meandepth.mm / 10000.0);
+ double sac = airuse / pressure * 60 / dive->duration.seconds;
+ plot_text(cr, 1, 0, maxx*0.95, maxy*0.95, "SAC: %4.2f", sac);
+ }
+}
+
+static void plot(cairo_t *cr, int w, int h, struct dive *dive)
+{
+ double topx, topy, maxx, maxy;
+ double scalex, scaley;
+
+ topx = w / 20.0;
+ topy = h / 20.0;
+ maxx = (w - 2*topx);
+ maxy = (h - 2*topy);
+
+ /* Cylinder pressure plot */
+ plot_cylinder_pressure(dive, cr, topx, topy, maxx, maxy);
+
+ /* Depth profile */
+ plot_depth_profile(dive, cr, topx, topy, maxx, maxy);
+
+ /* Text on top of all graphs.. */
+ plot_depth_text(dive, cr, topx, topy, maxx, maxy);
+
+ /* And info box in the lower right corner.. */
+ plot_info(dive, cr, topx, topy, maxx, maxy);