[PATCH] Don't show a SAC-rate of "0.00cuft/min"

[Linus Torvalds]

When we have no volume of has used, that doesn't actually mean you aren't 
breathing. It means that that cylinder doesn't have pressure information 
or perhaps wasn't used.

Showing it as "0.00cuft/min" (or liter/min) is just completely bogus, and 
actively visually misleading. Leave it empty.

This showed up both in the divelist, and in the the dive statistics page. 
The dive statistics case had a special case for "unknown", but only for 
the first gas. I don't think that was actually all that sane, and the 
logic was really odd - if you had gases that weren't used (or pressures 
not known) intermixed with gases you *did* have pressure for, the 
statistics thing did odd/wrong things.

This makes all the cylinders act the same way, leaving unknown gas use 
(and thus SAC) just empty for that gas.

There are bound to be odd combinations I didn't test, but this looks 
*much* better for the cases I did test (complete missing gas information, 
one tank with gas info, and a couple of gases with known pressures).

Signed-off-by: Linus Torvalds <torvalds at linux-foundation.org>
---

 qt-ui/maintab.cpp | 23 +++++++++++------------
 qt-ui/models.cpp  |  2 ++
 2 files changed, 13 insertions(+), 12 deletions(-)

diff --git a/qt-ui/maintab.cpp b/qt-ui/maintab.cpp
index bf108a9c170d..d7caab4391de 100644
--- a/qt-ui/maintab.cpp
+++ b/qt-ui/maintab.cpp
@@ -462,25 +462,24 @@ void MainTab::updateDiveInfo(bool clear)
 		ui.airTemperatureText->setText(get_temperature_string(displayed_dive.airtemp, true));
 		volume_t gases[MAX_CYLINDERS] = {};
 		get_gas_used(&displayed_dive, gases);
-		QString volumes = get_volume_string(gases[0], true);
+		QString volumes;
 		int mean[MAX_CYLINDERS], duration[MAX_CYLINDERS];
 		per_cylinder_mean_depth(&displayed_dive, select_dc(&displayed_dive), mean, duration);
 		volume_t sac;
-		QString SACs;
-		if (mean[0] && duration[0]) {
-			sac.mliter = gases[0].mliter / (depth_to_atm(mean[0], &displayed_dive) * duration[0] / 60.0);
-			SACs = get_volume_string(sac, true).append(tr("/min"));
-		} else {
-			SACs = QString(tr("unknown"));
-		}
-		for (int i = 1; i < MAX_CYLINDERS && gases[i].mliter != 0; i++) {
-			volumes.append("\n" + get_volume_string(gases[i], true));
+		QString SACs, separator;
+
+		SACs = ""; volumes = ""; separator = "";
+		for (int i = 0; i < MAX_CYLINDERS; i++) {
+			if (!gases[i].mliter)
+				continue;
+			volumes.append(separator + get_volume_string(gases[i], true));
 			if (duration[i]) {
 				sac.mliter = gases[i].mliter / (depth_to_atm(mean[i], &displayed_dive) * duration[i] / 60);
-				SACs.append("\n" + get_volume_string(sac, true).append(tr("/min")));
+				SACs.append(separator + get_volume_string(sac, true).append(tr("/min")));
 			} else {
-				SACs.append("\n");
+				SACs.append(separator);
 			}
+			separator = "\n";
 		}
 		ui.gasUsedText->setText(volumes);
 		ui.oxygenHeliumText->setText(get_gaslist(&displayed_dive));
diff --git a/qt-ui/models.cpp b/qt-ui/models.cpp
index 9d43da624f13..6cf5c2bd24b3 100644
--- a/qt-ui/models.cpp
+++ b/qt-ui/models.cpp
@@ -1250,6 +1250,8 @@ QString DiveItem::displaySac() const
 	const char *unit;
 	int decimal;
 	double value = get_volume_units(dive->sac, &decimal, &unit);
+	if (!value)
+		return "";
 	return QString::number(value, 'f', decimal).append(unit).append(tr("/min"));
 }