Add some air usage statistics to the dive plot

Show "absolute volume" used, and SAC/m (surface-equivalent per minute).

I'm not going to guarantee the calculations.  And I show the result in
cubic feet.  Sue me.

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Linus Torvalds 2011-09-06 14:46:46 -07:00
parent e88695ff72
commit 93c21a4dbc

View file

@ -27,7 +27,7 @@ static int round_feet_up(int feet)
return MAX(90, ROUND_UP(feet+5, 15));
}
static void plot_text(cairo_t *cr, double x, double y, const char *fmt, ...)
static void plot_text(cairo_t *cr, int xpos, int ypos, double x, double y, const char *fmt, ...)
{
cairo_text_extents_t extents;
char buffer[80];
@ -39,8 +39,26 @@ static void plot_text(cairo_t *cr, double x, double y, const char *fmt, ...)
cairo_text_extents(cr, buffer, &extents);
x -= extents.width/2 + extents.x_bearing;
y += extents.height * 1.2;
switch (xpos) {
case -1: /* Left-justify */
break;
case 0: /* Center */
x -= extents.width/2 + extents.x_bearing;
break;
case 1: /* Right-justify */
x -= extents.width + extents.x_bearing;
break;
}
switch (ypos) {
case -1: /* Top-justify */
break;
case 0: /* Center */
y -= extents.height/2 + extents.y_bearing;
break;
case 1: /* Bottom-justify */
y += extents.height * 1.2;
break;
}
cairo_move_to(cr, x, y);
cairo_text_path(cr, buffer);
@ -130,7 +148,7 @@ static void plot_depth_text(struct dive *dive, cairo_t *cr,
int sec = sample->time.seconds;
int depth = to_feet(sample->depth);
plot_text(cr, SCALE(sec, depth), "%d ft", depth);
plot_text(cr, 0, 1, SCALE(sec, depth), "%d ft", depth);
i = next_minmax(dive, i, 0);
if (!i)
break;
@ -263,6 +281,50 @@ static void plot_cylinder_pressure(struct dive *dive, cairo_t *cr,
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;
@ -282,6 +344,9 @@ static void plot(cairo_t *cr, int w, int h, struct dive *dive)
/* 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);
/* Bounding box last */
scalex = scaley = 1.0;
cairo_set_source_rgb(cr, 1, 1, 1);