dive models: add helper role to find trip above or below dive

This is only used in the mobile UI where the sort direction is fixed and we
refer to dives based on the tree model. So the terms used and the concepts
that these rely on should be guaranteed to be valid.

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

qt-models/divetripmodel.cpp

@@ -964,10 +964,19 @@ QVariant DiveTripModelTree::data(const QModelIndex &index, int role) const
 		const Item &item = items[index.row()];
 		return std::find(item.dives.begin(), item.dives.end(), current_dive) != item.dives.end();
 	}
-	if (entry.trip)
+	if (entry.trip) {
 		return tripData(entry.trip, index.column(), role);
-	else
+	} else if (entry.dive) {
+#if defined(SUBSURFACE_MOBILE)
+		if (role == MobileListModel::TripAbove)
+			return tripInDirection(entry.dive, +1);
+		if (role == MobileListModel::TripBelow)
+			return tripInDirection(entry.dive, -1);
+#endif
 		return diveData(entry.dive, index.column(), role);
+	} else {
+		return QVariant();
+	}
 }
 
 // After a trip changed, the top level might need to be reordered.
@@ -1136,6 +1145,26 @@ static QVector<dive *> visibleDives(const QVector<dive *> &dives)
 	return res;
 }
 
+#ifdef SUBSURFACE_MOBILE
+int DiveTripModelTree::tripInDirection(const struct dive *d, int direction) const
+{
+	for (int i = 0; i < (int)items.size(); ++i) {
+		if (items[i].d_or_t.dive == d || (items[i].d_or_t.trip && findDiveInTrip(i, d) != -1)) {
+			// now walk in the direction given to find a trip
+			int offset = direction;
+			while (i + offset >= 0 && i + offset < (int)items.size()) {
+				if (items[i + offset].d_or_t.trip && (!d->divetrip || items[i + offset].d_or_t.trip->id != d->divetrip->id))
+					// we found a trip (and if the dive is already in a trip, we make sure this is a different trip)
+					return items[i + offset].d_or_t.trip->id;
+				offset += direction;
+			}
+			break;
+		}
+	}
+	return -1;
+}
+#endif
+
 void DiveTripModelTree::divesAdded(dive_trip *trip, bool newTrip, const QVector<dive *> &divesIn)
 {
 	QVector <dive *> dives = visibleDives(divesIn);

qt-models/divetripmodel.h

@@ -77,7 +77,6 @@ public:
 	// Used for sorting. This is a bit of a layering violation, as sorting should be performed
 	// by the higher-up QSortFilterProxyModel, but it makes things so much easier!
 	virtual bool lessThan(const QModelIndex &i1, const QModelIndex &i2) const = 0;
-
 signals:
 	// The propagation of selection changes is complex.
 	// The control flow of dive-selection goes:
@@ -120,6 +119,7 @@ public slots:
 
 public:
 	DiveTripModelTree(QObject *parent = nullptr);
+	int tripInDirection(const struct dive *d, int direction) const;
 private:
 	int rowCount(const QModelIndex &parent) const override;
 	void clearData() override;

qt-models/mobilelistmodel.cpp

@@ -47,6 +47,8 @@ QHash<int, QByteArray> MobileListModelBase::roleNames() const
 	roles[FirstGasRole] = "firstGas";
 	roles[SelectedRole] = "selected";
 	roles[DiveInTripRole] = "diveInTrip";
+	roles[TripAbove] = "tripAbove";
+	roles[TripBelow] = "tripBelow";
 	return roles;
 }
 

qt-models/mobilelistmodel.h

@@ -55,6 +55,8 @@ public:
 		FirstGasRole,
 		SelectedRole,
 		DiveInTripRole,
+		TripAbove,
+		TripBelow,
 	};
 	QHash<int, QByteArray> roleNames() const override;
 protected: