Get the math right for cylinder model setData function

This is a fun one.

We only want to mark the divelist changed if the user actually changed
something. So we try really hard to compare what was entered with what was
there and only if it is different do we overwrite existing values and
record this as a change to the divelist.

An additional challenge here is the fact that the user needs to enter a
working pressure before they can enter a size (when in cuft mode). That is
not really intuitive. We work around this by assuming working pressure is
3000psi if a size is given in cuft - but then if the user changes the
working pressure, that changes the volume. Now going back and changing the
volume again does the trick. Or enter the working pressure FIRST and then
the volume...

This also changes the incorrect MAXPRESSURE to WORKINGPRESSURE and uses
the text WorkPress in English (Gtk code used MaxPress which was simply
wrong - this is just the design pressure or working pressure, not some
hard maximum. In fact, people quite commonly "overfill" these tanks.

Signed-off-by: Dirk Hohndel <dirk@hohndel.org>

4 files changed, 85 insertions, 34 deletions

diff --git a/dive.c b/dive.c
index 2c2307e41..b005e9d34 100644
--- a/dive.c
+++ b/dive.c
@@ -312,6 +312,11 @@ int gas_volume(cylinder_t *cyl, pressure_t p)
 	return cyl->type.size.mliter * surface_volume_multiplier(p);
 }
 
+int wet_volume(double cuft, pressure_t p)
+{
+	return cuft_to_l(cuft) * 1000 / surface_volume_multiplier(p);
+}
+
 /*
  * If the cylinder tank pressures are within half a bar
  * (about 8 PSI) of the sample pressures, we consider it
diff --git a/dive.h b/dive.h
index 968804581..a1febdd16 100644
--- a/dive.h
+++ b/dive.h
@@ -221,7 +221,7 @@ static inline double psi_to_bar(double psi)
 	return psi / 14.5037738;
 }
 
-static inline unsigned long psi_to_mbar(double psi)
+static inline long psi_to_mbar(double psi)
 {
 	return psi_to_bar(psi)*1000 + 0.5;
 }
@@ -238,6 +238,7 @@ static inline double bar_to_atm(double bar)
 
 /* Volume in mliter of a cylinder at pressure 'p' */
 extern int gas_volume(cylinder_t *cyl, pressure_t p);
+extern int wet_volume(double cuft, pressure_t p);
 
 static inline int mbar_to_PSI(int mbar)
 {
diff --git a/qt-ui/models.cpp b/qt-ui/models.cpp
index 3bbc79f72..b38295bc5 100644
--- a/qt-ui/models.cpp
+++ b/qt-ui/models.cpp
@@ -34,8 +34,8 @@ QVariant CylindersModel::headerData(int section, Qt::Orientation orientation, in
 		case SIZE:
 			ret = tr("Size");
 			break;
-		case MAXPRESS:
-			ret = tr("MaxPress");
+		case WORKINGPRESS:
+			ret = tr("WorkPress");
 			break;
 		case START:
 			ret = tr("Start");
@@ -77,14 +77,14 @@ QVariant CylindersModel::data(const QModelIndex& index, int role) const
 			// sizes take working pressure into account...
 			if (cyl->type.size.mliter) {
 				if (prefs.units.volume == prefs.units.CUFT) {
-					int cuft = ml_to_cuft(gas_volume(cyl, cyl->type.workingpressure));
+					int cuft = 0.5 + ml_to_cuft(gas_volume(cyl, cyl->type.workingpressure));
 					ret = QString("%1cuft").arg(cuft);
 				} else {
 					ret = QString("%1l").arg(cyl->type.size.mliter / 1000.0, 0, 'f', 1);
 				}
 			}
 			break;
-		case MAXPRESS:
+		case WORKINGPRESS:
 			if (cyl->type.workingpressure.mbar)
 				ret = get_pressure_string(cyl->type.workingpressure, TRUE);
 			break;
@@ -114,45 +114,90 @@ QVariant CylindersModel::data(const QModelIndex& index, int role) const
 	return ret;
 }
 
+#define CHANGED(_t,_u1,_u2) value._t() != data(index, role).toString().replace(_u1,"").replace(_u2,"")._t()
+
 bool CylindersModel::setData(const QModelIndex& index, const QVariant& value, int role)
 {
 	cylinder_t *cyl = &current->cylinder[index.row()];
-	switch(index.column()){
-		case TYPE:{
-			QByteArray desc = value.toByteArray();
-			cyl->type.description = strdup(desc.data());
-			break;
+	switch(index.column()) {
+	case TYPE:
+		if (!value.isNull()) {
+			char *text = value.toByteArray().data();
+			if (strcmp(cyl->type.description, text)) {
+				cyl->type.description = strdup(text);
+				mark_divelist_changed(TRUE);
+			}
 		}
-		case SIZE:
-			// we can't use get_volume_string because the idiotic imperial tank
-			// sizes take working pressure into account...
-			if (cyl->type.size.mliter) {
+		break;
+	case SIZE:
+		if (CHANGED(toDouble, "cuft", "l")) {
+			// if units are CUFT then this value is meaningless until we have working pressure
+			if (value.toDouble() != 0.0) {
 				if (prefs.units.volume == prefs.units.CUFT) {
-					double liters = cuft_to_l(value.toDouble());
-					cyl->type.size.mliter = liters * 1000.0;
+					if (cyl->type.workingpressure.mbar == 0)
+						// this is a hack as we can't store a wet size
+						// without working pressure in cuft mode
+						// so we assume it's an aluminum tank at 3000psi
+						cyl->type.workingpressure.mbar = psi_to_mbar(3000);
+					if (cyl->type.size.mliter != wet_volume(value.toDouble(), cyl->type.workingpressure)) {
+						mark_divelist_changed(TRUE);
+						cyl->type.size.mliter = wet_volume(value.toDouble(), cyl->type.workingpressure);
+					}
 				} else {
-					cyl->type.size.mliter = value.toDouble() * 1000.0;
+					if (cyl->type.size.mliter != value.toDouble() * 1000.0) {
+						mark_divelist_changed(TRUE);
+						cyl->type.size.mliter = value.toDouble() * 1000.0;
+					}
 				}
 			}
-			break;
-		case MAXPRESS:
-			cyl->type.workingpressure.mbar = value.toInt();
-			break;
-		case START:
-			cyl->start.mbar = value.toInt();
-			break;
-		case END:
-			cyl->end.mbar = value.toInt();
-			break;
-		case O2:
+		}
+		break;
+	case WORKINGPRESS:
+		if (CHANGED(toDouble, "psi", "bar")) {
+			if (value.toDouble() != 0.0) {
+				if (prefs.units.pressure == prefs.units.PSI)
+					cyl->type.workingpressure.mbar = psi_to_mbar(value.toDouble());
+				else
+					cyl->type.workingpressure.mbar = value.toDouble() * 1000;
+				mark_divelist_changed(TRUE);
+			}
+		}
+		break;
+	case START:
+		if (CHANGED(toDouble, "psi", "bar")) {
+			if (value.toDouble() != 0.0) {
+				if (prefs.units.pressure == prefs.units.PSI)
+					cyl->start.mbar = psi_to_mbar(value.toDouble());
+				else
+					cyl->start.mbar = value.toDouble() * 1000;
+				mark_divelist_changed(TRUE);
+			}
+		}
+		break;
+	case END:
+		if (CHANGED(toDouble, "psi", "bar")) {
+			if (value.toDouble() != 0.0) {
+				if (prefs.units.pressure == prefs.units.PSI)
+					cyl->end.mbar = psi_to_mbar(value.toDouble());
+				else
+					cyl->end.mbar = value.toDouble() * 1000;
+			}
+		}
+		break;
+	case O2:
+		if (CHANGED(toInt, "%", "%")) {
 			cyl->gasmix.o2.permille = value.toInt() * 10 - 5;
-			break;
-		case HE:
+			mark_divelist_changed(TRUE);
+		}
+		break;
+	case HE:
+		if (CHANGED(toInt, "%", "%")) {
 			cyl->gasmix.he.permille = value.toInt() * 10 - 5;
-			break;
+			mark_divelist_changed(TRUE);
+		}
+		break;
 	}
-
-    return QAbstractItemModel::setData(index, value, role);
+	return QAbstractItemModel::setData(index, value, role);
 }
 
 int CylindersModel::rowCount(const QModelIndex& parent) const
diff --git a/qt-ui/models.h b/qt-ui/models.h
index b207ff0fd..6793a7fa8 100644
--- a/qt-ui/models.h
+++ b/qt-ui/models.h
@@ -38,7 +38,7 @@ private:
 class CylindersModel : public QAbstractTableModel {
 Q_OBJECT
 public:
-	enum Column {REMOVE, TYPE, SIZE, MAXPRESS, START, END, O2, HE,  COLUMNS};
+	enum Column {REMOVE, TYPE, SIZE, WORKINGPRESS, START, END, O2, HE,  COLUMNS};
 
 	explicit CylindersModel(QObject* parent = 0);
 	/*reimp*/ QVariant headerData(int section, Qt::Orientation orientation, int role = Qt::DisplayRole) const;