Convert the atmospheric pressure in the Information Tab to an editable field

The Information tab shows the atmospheric pressure. Make this value editable
and also ensure that changes to it are undo-able.

Signed-off-by: willemferguson <willemferguson@zoology.up.ac.za>

19 files changed, 323 insertions, 20 deletions

diff --git a/core/dive.c b/core/dive.c
index 0f67ebe61..d20350a80 100644
--- a/core/dive.c
+++ b/core/dive.c
@@ -1317,9 +1317,10 @@ static struct event *find_previous_event(struct divecomputer *dc, struct event *
 	return previous;
 }
 
-static void fixup_surface_pressure(struct dive *dive)
+pressure_t calculate_surface_pressure(const struct dive *dive)
 {
-	struct divecomputer *dc;
+	const struct divecomputer *dc;
+	pressure_t res;
 	int sum = 0, nr = 0;
 
 	for_each_dc (dive, dc) {
@@ -1328,8 +1329,24 @@ static void fixup_surface_pressure(struct dive *dive)
 			nr++;
 		}
 	}
-	if (nr)
-		dive->surface_pressure.mbar = (sum + nr / 2) / nr;
+	res.mbar = nr ? (sum + nr / 2) / nr : 0;
+	return res;
+}
+
+static void fixup_surface_pressure(struct dive *dive)
+{
+	dive->surface_pressure = calculate_surface_pressure(dive);
+}
+
+/* if the surface pressure in the dive data is redundant to the calculated
+ * value (i.e., it was added by running fixup on the dive) return 0,
+ * otherwise return the air temperature given in the dive */
+pressure_t un_fixup_surface_pressure(const struct dive *d)
+{
+	pressure_t res = d->surface_pressure;
+	if (res.mbar && res.mbar == calculate_surface_pressure(d).mbar)
+		res.mbar = 0;
+	return res;
 }
 
 static void fixup_water_salinity(struct dive *dive)
@@ -1823,7 +1840,8 @@ struct dive *fixup_dive(struct dive *dive)
 		fixup_dive_dc(dive, dc);
 
 	fixup_water_salinity(dive);
-	fixup_surface_pressure(dive);
+	if (!dive->surface_pressure.mbar)
+		fixup_surface_pressure(dive);
 	fixup_meandepth(dive);
 	fixup_duration(dive);
 	fixup_watertemp(dive);
diff --git a/core/dive.h b/core/dive.h
index 6f75aff43..7aea050b6 100644
--- a/core/dive.h
+++ b/core/dive.h
@@ -533,6 +533,8 @@ extern bool dive_or_trip_less_than(struct dive_or_trip a, struct dive_or_trip b)
 extern void sort_dive_table(struct dive_table *table);
 extern void sort_trip_table(struct trip_table *table);
 extern struct dive *fixup_dive(struct dive *dive);
+extern pressure_t calculate_surface_pressure(const struct dive *dive);
+extern pressure_t un_fixup_surface_pressure(const struct dive *d);
 extern void fixup_dc_duration(struct divecomputer *dc);
 extern int dive_getUniqID();
 extern unsigned int dc_airtemp(const struct divecomputer *dc);
diff --git a/core/load-git.c b/core/load-git.c
index c6b3400a8..a0baedecd 100644
--- a/core/load-git.c
+++ b/core/load-git.c
@@ -76,6 +76,13 @@ static weight_t get_weight(const char *line)
 	return w;
 }
 
+static pressure_t get_airpressure(const char *line)
+{
+	pressure_t p;
+	p.mbar = lrint(ascii_strtod(line, NULL));
+	return p;
+}
+
 static pressure_t get_pressure(const char *line)
 {
 	pressure_t p;
@@ -245,6 +252,9 @@ static void parse_dive_airtemp(char *line, struct membuffer *str, void *_dive)
 static void parse_dive_watertemp(char *line, struct membuffer *str, void *_dive)
 { UNUSED(str); struct dive *dive = _dive; dive->watertemp = get_temperature(line); }
 
+static void parse_dive_airpressure(char *line, struct membuffer *str, void *_dive)
+{ UNUSED(str); struct dive *dive = _dive; dive->surface_pressure = get_airpressure(line); }
+
 static void parse_dive_duration(char *line, struct membuffer *str, void *_dive)
 { UNUSED(str); struct dive *dive = _dive; dive->duration = get_duration(line); }
 
@@ -980,7 +990,7 @@ static void divecomputer_parser(char *line, struct membuffer *str, void *_dc)
 struct keyword_action dive_action[] = {
 #undef D
 #define D(x) { #x, parse_dive_ ## x }
-	D(airtemp), D(buddy), D(cylinder), D(divemaster), D(divesiteid), D(duration),
+	D(airpressure), D(airtemp), D(buddy), D(cylinder), D(divemaster), D(divesiteid), D(duration),
 	D(gps), D(location), D(notes), D(notrip), D(rating), D(suit),
 	D(tags), D(visibility), D(watertemp), D(weightsystem)
 };
diff --git a/core/parse-xml.c b/core/parse-xml.c
index 483614c6e..43d0049a7 100644
--- a/core/parse-xml.c
+++ b/core/parse-xml.c
@@ -1306,6 +1306,8 @@ static void try_to_fill_dive(struct dive *dive, const char *name, char *buf, str
 		return;
 	if (MATCH("visibility.dive", get_rating, &dive->visibility))
 		return;
+	if (MATCH_STATE("airpressure.dive", pressure, &dive->surface_pressure))
+		return;
 	if (state->cur_ws_index < MAX_WEIGHTSYSTEMS) {
 		if (MATCH("description.weightsystem", utf8_string, &dive->weightsystem[state->cur_ws_index].description))
 			return;
diff --git a/core/save-git.c b/core/save-git.c
index b13921c60..a5f6f0dde 100644
--- a/core/save-git.c
+++ b/core/save-git.c
@@ -425,10 +425,13 @@ static void save_dc(struct membuffer *b, struct dive *dive, struct divecomputer
  */
 static void create_dive_buffer(struct dive *dive, struct membuffer *b)
 {
+	pressure_t surface_pressure = un_fixup_surface_pressure(dive);
 	if (dive->dc.duration.seconds > 0)
 		put_format(b, "duration %u:%02u min\n", FRACTION(dive->dc.duration.seconds, 60));
 	SAVE("rating", rating);
 	SAVE("visibility", visibility);
+	if (surface_pressure.mbar)
+		SAVE("airpressure", surface_pressure.mbar);
 	cond_put_format(dive->notrip, b, "notrip\n");
 	save_tags(b, dive->tag_list);
 	if (dive->dive_site)
diff --git a/core/save-xml.c b/core/save-xml.c
index 02cb2bf87..f043ab6d8 100644
--- a/core/save-xml.c
+++ b/core/save-xml.c
@@ -473,6 +473,7 @@ static void save_picture(struct membuffer *b, struct picture *pic)
 void save_one_dive_to_mb(struct membuffer *b, struct dive *dive, bool anonymize)
 {
 	struct divecomputer *dc;
+	pressure_t surface_pressure = un_fixup_surface_pressure(dive);
 
 	put_string(b, "<dive");
 	if (dive->number)
@@ -488,6 +489,8 @@ void save_one_dive_to_mb(struct membuffer *b, struct dive *dive, bool anonymize)
 		put_format(b, " divesiteid='%8x'", dive->dive_site->uuid);
 	}
 	show_date(b, dive->when);
+	if (surface_pressure.mbar)
+		put_pressure(b, surface_pressure, " airpressure='", " bar'");
 	if (dive->dc.duration.seconds > 0)
 		put_format(b, " duration='%u:%02u min'>\n",
 			   FRACTION(dive->dc.duration.seconds, 60));
diff --git a/core/subsurface-qt/DiveListNotifier.h b/core/subsurface-qt/DiveListNotifier.h
index b57595aa6..95a67a1e8 100644
--- a/core/subsurface-qt/DiveListNotifier.h
+++ b/core/subsurface-qt/DiveListNotifier.h
@@ -19,6 +19,7 @@ enum class DiveField {
 	DURATION,
 	AIR_TEMP,
 	WATER_TEMP,
+	ATM_PRESS,
 	DIVESITE,
 	DIVEMASTER,
 	BUDDY,
diff --git a/core/units.h b/core/units.h
index c9920ac14..2307622e9 100644
--- a/core/units.h
+++ b/core/units.h
@@ -254,6 +254,17 @@ static inline int mbar_to_PSI(int mbar)
 	return to_PSI(p);
 }
 
+static inline int32_t altitude_to_pressure(int32_t altitude) 	// altitude in mm above sea level
+{						// returns atmospheric pressure in mbar
+	return (int32_t) (1013.0 * exp(- altitude / 7800000.0));
+}
+
+
+static inline int32_t pressure_to_altitude(int32_t pressure)	// pressure in mbar
+{						// returns altitude in mm above sea level
+	return (int32_t) (log(1013.0 / pressure) * 7800000);
+}
+
 /*
  * We keep our internal data in well-specified units, but
  * the input and output may come in some random format. This
diff --git a/desktop-widgets/command.cpp b/desktop-widgets/command.cpp
index 00bb49872..e5244e92a 100644
--- a/desktop-widgets/command.cpp
+++ b/desktop-widgets/command.cpp
@@ -171,6 +171,11 @@ void editWaterTemp(int newValue, bool currentDiveOnly)
 	execute(new EditWaterTemp(newValue, currentDiveOnly));
 }
 
+void editAtmPress(int newValue, bool currentDiveOnly)
+{
+	execute(new EditAtmPress(newValue, currentDiveOnly));
+}
+
 void editDepth(int newValue, bool currentDiveOnly)
 {
 	execute(new EditDepth(newValue, currentDiveOnly));
diff --git a/desktop-widgets/command.h b/desktop-widgets/command.h
index 8e8157acf..2686255ee 100644
--- a/desktop-widgets/command.h
+++ b/desktop-widgets/command.h
@@ -61,6 +61,7 @@ void editRating(int newValue, bool currentDiveOnly);
 void editVisibility(int newValue, bool currentDiveOnly);
 void editAirTemp(int newValue, bool currentDiveOnly);
 void editWaterTemp(int newValue, bool currentDiveOnly);
+void editAtmPress(int newValue, bool currentDiveOnly);
 void editDepth(int newValue, bool currentDiveOnly);
 void editDuration(int newValue, bool currentDiveOnly);
 void editDiveSite(struct dive_site *newValue, bool currentDiveOnly);
diff --git a/desktop-widgets/command_edit.cpp b/desktop-widgets/command_edit.cpp
index 3419749d7..5207d1ac1 100644
--- a/desktop-widgets/command_edit.cpp
+++ b/desktop-widgets/command_edit.cpp
@@ -248,6 +248,27 @@ DiveField EditWaterTemp::fieldId() const
 	return DiveField::WATER_TEMP;
 }
 
+// ***** Atmospheric pressure *****
+void EditAtmPress::set(struct dive *d, int value) const
+{
+	d->surface_pressure.mbar = value > 0 ? (uint32_t)value : 0u;
+}
+
+int EditAtmPress::data(struct dive *d) const
+{
+	return (int)d->surface_pressure.mbar;
+}
+
+QString EditAtmPress::fieldName() const
+{
+	return tr("Atm. pressure");
+}
+
+DiveField EditAtmPress::fieldId() const
+{
+	return DiveField::ATM_PRESS;
+}
+
 // ***** Duration *****
 void EditDuration::set(struct dive *d, int value) const
 {
diff --git a/desktop-widgets/command_edit.h b/desktop-widgets/command_edit.h
index 1f627c7ef..a1050d65e 100644
--- a/desktop-widgets/command_edit.h
+++ b/desktop-widgets/command_edit.h
@@ -102,6 +102,15 @@ public:
 	DiveField fieldId() const override;
 };
 
+class EditAtmPress : public EditBase<int> {
+public:
+	using EditBase<int>::EditBase;	// Use constructor of base class.
+	void set(struct dive *d, int value) const override;
+	int data(struct dive *d) const override;
+	QString fieldName() const override;
+	DiveField fieldId() const override;
+};
+
 class EditDuration : public EditBase<int> {
 public:
 	using EditBase<int>::EditBase;	// Use constructor of base class.
diff --git a/desktop-widgets/tab-widgets/TabDiveInformation.cpp b/desktop-widgets/tab-widgets/TabDiveInformation.cpp
index 5fe6ea714..4511f9b61 100644
--- a/desktop-widgets/tab-widgets/TabDiveInformation.cpp
+++ b/desktop-widgets/tab-widgets/TabDiveInformation.cpp
@@ -2,15 +2,24 @@
 #include "TabDiveInformation.h"
 #include "ui_TabDiveInformation.h"
 #include "../tagwidget.h"
+#include "core/units.h"
+#include "core/dive.h"
+#include "desktop-widgets/command.h"
 
 #include <core/qthelper.h>
 #include <core/statistics.h>
 #include <core/display.h>
 
+#define COMBO_CHANGED 0
+#define TEXT_EDITED 1
+
 TabDiveInformation::TabDiveInformation(QWidget *parent) : TabBase(parent), ui(new Ui::TabDiveInformation())
 {
 	ui->setupUi(this);
 	connect(&diveListNotifier, &DiveListNotifier::divesChanged, this, &TabDiveInformation::divesChanged);
+	QStringList atmPressTypes { "mbar", get_depth_unit() ,"use dc"};
+	ui->atmPressType->insertItems(0, atmPressTypes);
+	pressTypeIndex = 0;
 }
 
 TabDiveInformation::~TabDiveInformation()
@@ -32,7 +41,7 @@ void TabDiveInformation::clear()
 	ui->averageDepthText->clear();
 	ui->waterTemperatureText->clear();
 	ui->airTemperatureText->clear();
-	ui->airPressureText->clear();
+	ui->atmPressVal->clear();
 	ui->salinityText->clear();
 }
 
@@ -74,6 +83,17 @@ void TabDiveInformation::updateProfile()
 			" ", current_dive->dc.divemode == FREEDIVE));
 
 	ui->sacText->setText( mean[0] ? SACs : QString());
+
+	if (current_dive->surface_pressure.mbar == 0) {
+		ui->atmPressVal->clear();			// If no atm pressure for dive then clear text box
+	}
+	else {
+
+		ui->atmPressVal->setEnabled(true);
+		QString pressStr;
+		pressStr.sprintf("%d",current_dive->surface_pressure.mbar);
+		ui->atmPressVal->setText(pressStr);		// else display atm pressure
+	}
 }
 
 // Update fields that depend on start of dive
@@ -99,15 +119,15 @@ void TabDiveInformation::updateData()
 	ui->waterTemperatureText->setText(get_temperature_string(current_dive->watertemp, true));
 	ui->airTemperatureText->setText(get_temperature_string(current_dive->airtemp, true));
 
-	if (current_dive->surface_pressure.mbar) 	/* this is ALWAYS displayed in mbar */
-		ui->airPressureText->setText(QString("%1mbar").arg(current_dive->surface_pressure.mbar));
-	else
-		ui->airPressureText->clear();
-
 	if (current_dive->salinity)
 		ui->salinityText->setText(QString("%1g/ℓ").arg(current_dive->salinity / 10.0));
 	else
 		ui->salinityText->clear();
+
+	ui->atmPressType->setEditable(true);
+	ui->atmPressType->setItemText(1, get_depth_unit());  // Check for changes in depth unit (imperial/metric)
+	ui->atmPressType->setEditable(false);
+	ui->atmPressType->setCurrentIndex(0);  // Set the atmospheric pressure combo box to mbar
 }
 
 // This function gets called if a field gets updated by an undo command.
@@ -130,6 +150,9 @@ void TabDiveInformation::divesChanged(dive_trip *trip, const QVector<dive *> &di
 	case DiveField::WATER_TEMP:
 		ui->waterTemperatureText->setText(get_temperature_string(current_dive->watertemp, true));
 		break;
+	case DiveField::ATM_PRESS:
+		ui->atmPressVal->setText(ui->atmPressVal->text().sprintf("%d",current_dive->surface_pressure.mbar));
+		break;
 	case DiveField::DATETIME:
 		updateWhen();
 		break;
@@ -137,3 +160,47 @@ void TabDiveInformation::divesChanged(dive_trip *trip, const QVector<dive *> &di
 		break;
 	}
 }
+
+void TabDiveInformation::on_atmPressType_currentIndexChanged(int index) { updateTextBox(COMBO_CHANGED); }
+
+void TabDiveInformation::on_atmPressVal_editingFinished() { updateTextBox(TEXT_EDITED); }
+
+void TabDiveInformation::updateTextBox(int event) // Either the text box has been edited or the pressure type has changed.
+{                                       // Either way this gets a numeric value and puts it on the text box atmPressVal,
+	pressure_t atmpress = { 0 };    // then stores it in dive->surface_pressure.The undo stack for the text box content is
+	double altitudeVal;             // maintained even though two independent events trigger saving the text box contents.
+	if (current_dive) {
+		switch (ui->atmPressType->currentIndex()) {
+		case 0:		// If an atm pressure has been specified in mbar:
+			if (event == TEXT_EDITED)         // this is only triggered by on_atmPressVal_editingFinished()
+				atmpress.mbar = ui->atmPressVal->text().toInt();    // use the specified mbar pressure
+			break;
+		case 1:		// If an altitude has been specified:
+			if (event == TEXT_EDITED) {	// this is only triggered by on_atmPressVal_editingFinished()
+				altitudeVal = (ui->atmPressVal->text().toFloat());    // get altitude from text box
+				if (prefs.units.length == units::FEET)         // if altitude in feet
+					altitudeVal = feet_to_mm(altitudeVal); // imperial: convert altitude from feet to mm
+				else
+					altitudeVal = altitudeVal * 1000;     // metric: convert altitude from meters to mm
+				atmpress.mbar = altitude_to_pressure((int32_t) altitudeVal); // convert altitude (mm) to pressure (mbar)
+				ui->atmPressVal->setText(ui->atmPressVal->text().sprintf("%d",atmpress.mbar));
+				ui->atmPressType->setCurrentIndex(0);    // reset combobox to mbar
+			} else { // i.e. event == COMBO_CHANGED, that is, "m" or "ft" was selected from combobox
+				ui->atmPressVal->clear();   // Clear the text box so that altitude can be typed
+			}
+			break;
+		case 2:          // i.e. event = COMBO_CHANGED, that is, the option "Use dc" was selected from combobox
+			atmpress = calculate_surface_pressure(current_dive);	// re-calculate air pressure from dc data
+			ui->atmPressVal->setText(QString::number(atmpress.mbar)); // display it in text box
+			ui->atmPressType->setCurrentIndex(0);          // reset combobox to mbar
+			break;
+		default:
+			atmpress.mbar = 1013;    // This line should never execute
+			break;
+		}
+		if (atmpress.mbar)
+			Command::editAtmPress(atmpress.mbar, false);      // and save the pressure for undo
+	}
+}
+
+
diff --git a/desktop-widgets/tab-widgets/TabDiveInformation.h b/desktop-widgets/tab-widgets/TabDiveInformation.h
index a61b9b414..e2b2e3c94 100644
--- a/desktop-widgets/tab-widgets/TabDiveInformation.h
+++ b/desktop-widgets/tab-widgets/TabDiveInformation.h
@@ -18,10 +18,14 @@ public:
 	void clear() override;
 private slots:
 	void divesChanged(dive_trip *trip, const QVector<dive *> &dives, DiveField field);
+	void on_atmPressVal_editingFinished();
+	void on_atmPressType_currentIndexChanged(int index);
 private:
 	Ui::TabDiveInformation *ui;
 	void updateProfile();
 	void updateWhen();
+	int pressTypeIndex;
+	void updateTextBox(int event);
 };
 
 #endif
diff --git a/desktop-widgets/tab-widgets/TabDiveInformation.ui b/desktop-widgets/tab-widgets/TabDiveInformation.ui
index f81ab6fe5..b35ddf01d 100644
--- a/desktop-widgets/tab-widgets/TabDiveInformation.ui
+++ b/desktop-widgets/tab-widgets/TabDiveInformation.ui
@@ -224,25 +224,37 @@
          </layout>
         </widget>
        </item>
-       <item row="2" column="2">
+
+       <item row="2" column="2" colspan="1">
         <widget class="QGroupBox" name="groupBox_10">
          <property name="title">
-          <string>Air pressure</string>
+          <string>Atm. pressure</string>
          </property>
+         <property name="alignment">
+          <set>Qt::AlignHCenter</set>
+         </property>
+           <property name="sizePolicy">
+            <sizepolicy hsizetype="Preferred" vsizetype="Maximum">
+             <horstretch>0</horstretch>
+             <verstretch>0</verstretch>
+            </sizepolicy>
+           </property>
          <layout class="QHBoxLayout" name="diveInfoAirPressureLayout">
           <item>
-           <widget class="QLabel" name="airPressureText">
-            <property name="text">
-             <string/>
-            </property>
-            <property name="alignment">
-             <set>Qt::AlignCenter</set>
+           <widget class="QLineEdit" name="atmPressVal">
+            <property name="readOnly">
+             <bool>false</bool>
             </property>
            </widget>
           </item>
+          <item>
+           <widget class="QComboBox" name="atmPressType">
+           </widget>
+          </item>
          </layout>
         </widget>
        </item>
+
        <item row="3" column="2">
         <widget class="QGroupBox" name="groupBox_9">
          <property name="title">
diff --git a/dives/TestAtmPress.xml b/dives/TestAtmPress.xml
new file mode 100644
index 000000000..93bbe3960
--- /dev/null
+++ b/dives/TestAtmPress.xml
@@ -0,0 +1,50 @@
+<divelog program='subsurface' version='3'>
+<settings>
+  <autogroup state='1' />
+</settings>
+<divesites>
+<site uuid='4fdcf19b' name='Loc1'>
+</site>
+<site uuid='b15ad032' name='Loc2'>
+</site>
+</divesites>
+<dives>
+<trip date='2019-04-09' time='09:15:16' location='Scottburgh'>
+<dive number='524' tripflag='NOTRIP' divesiteid='b15ad032' date='2019-04-09' time='09:15:16' airpressure='1.012 bar' duration='42:08 min'>
+  <cylinder size='10.0 l' workpressure='232.0 bar' description='10ℓ 232 bar' o2='30.0%' depth='42.96 m' />
+  <cylinder size='10.0 l' workpressure='232.0 bar' description='10ℓ 232 bar' o2='30.0%' depth='42.96 m' />
+  <weightsystem weight='3.0 kg' description='belt' />
+  <divecomputer model='Uwatec Galileo Trimix' deviceid='462769ce' diveid='14106bf6'>
+  <depth max='30.068 m' mean='21.394 m' />
+  <temperature air='24.6 C' water='23.2 C' />
+  <water salinity='1025 g/l' />
+  <sample time='0:00 min' depth='0.0 m' temp='24.4 C' rbt='99:00 min' />
+  <sample time='0:04 min' depth='2.439 m' temp='24.8 C' rbt='99:00 min' />
+  <sample time='0:08 min' depth='3.395 m' temp='24.4 C' rbt='99:00 min' />
+  <sample time='0:12 min' depth='3.902 m' temp='24.8 C' pressure='208.5 bar' rbt='99:00 min' />
+  <sample time='45:16 min' depth='4.488 m' pressure='208.25 bar' rbt='98:00 min' />
+  </divecomputer>
+</dive>
+<dive number='525' divesiteid='4fdcf19b' date='2019-04-10' time='08:14:01' airpressure='0.991 bar' duration='41:24 min'>
+  <cylinder size='10.0 l' workpressure='232.0 bar' description='10ℓ 232 bar' o2='31.0%' depth='41.25 m' />
+  <cylinder description='unknown' o2='31.0%' depth='41.25 m' />
+  <weightsystem weight='3.0 kg' description='belt' />
+  <divecomputer model='Uwatec Galileo Trimix' deviceid='462769ce' diveid='04c0cf94'>
+  <depth max='26.166 m' mean='19.561 m' />
+  <temperature air='24.8 C' water='23.6 C' />
+  <water salinity='1025 g/l' />
+  <sample time='0:00 min' depth='0.0 m' temp='26.8 C' rbt='99:00 min' />
+  <sample time='0:04 min' depth='3.61 m' rbt='99:00 min' />
+  <sample time='0:08 min' depth='4.741 m' temp='25.6 C' pressure='217.25 bar' rbt='99:00 min' />
+  <sample time='0:12 min' depth='6.478 m' pressure='216.75 bar' rbt='97:00 min' />
+  <sample time='0:16 min' depth='7.785 m' rbt='94:00 min' />
+  <sample time='44:04 min' depth='0.0 m' rbt='99:00 min' />
+  <sample time='44:08 min' depth='0.02 m' rbt='99:00 min' />
+  <sample time='44:12 min' depth='0.098 m' rbt='99:00 min' />
+  <sample time='44:16 min' depth='0.059 m' rbt='99:00 min' />
+  <sample time='44:20 min' depth='0.059 m' rbt='99:00 min' />
+  </divecomputer>
+</dive>
+</trip>
+</dives>
+</divelog>
diff --git a/tests/CMakeLists.txt b/tests/CMakeLists.txt
index 229054631..887e1b34d 100644
--- a/tests/CMakeLists.txt
+++ b/tests/CMakeLists.txt
@@ -92,6 +92,7 @@ TEST(TestUnitConversion testunitconversion.cpp)
 TEST(TestProfile testprofile.cpp)
 TEST(TestGpsCoords testgpscoords.cpp)
 TEST(TestParse testparse.cpp)
+TEST(TestAirPressure testAirPressure.cpp)
 if (BTSUPPORT)
 	TEST(TestHelper testhelper.cpp)
 endif()
@@ -128,6 +129,7 @@ add_custom_target(check COMMAND ${CMAKE_CTEST_COMMAND}
 	TestParse
 	TestGitStorage
 	TestPlan
+	TestAirPressure
 	TestDiveSiteDuplication
 	TestRenumber
 	TestPicture
diff --git a/tests/testAirPressure.cpp b/tests/testAirPressure.cpp
new file mode 100644
index 000000000..aa6b13014
--- /dev/null
+++ b/tests/testAirPressure.cpp
@@ -0,0 +1,63 @@
+// SPDX-License-Identifier: GPL-2.0
+#include "testAirPressure.h"
+#include "core/divesite.h"
+#include "core/divelist.h"
+#include "core/file.h"
+#include "core/dive.h"
+#include <QString>
+#include <core/qthelper.h>
+
+void TestAirPressure::initTestCase()
+{
+	/* we need to manually tell that the resource exists, because we are using it as library. */
+	Q_INIT_RESOURCE(subsurface);
+}
+
+void TestAirPressure::get_dives()
+{
+	struct dive *dive;
+	verbose = 1;
+
+	QCOMPARE(parse_file(SUBSURFACE_TEST_DATA "/dives/TestAtmPress.xml", &dive_table, &trip_table, &dive_site_table), 0);
+	dive = get_dive(0);
+	dive->selected = true;
+	QVERIFY(dive != NULL);
+}
+
+void TestAirPressure::testReadAirPressure()
+{
+	struct dive *dive;
+	dive = get_dive(0);
+	QVERIFY(dive != NULL);
+	dive->selected = true;
+	QCOMPARE(1012, dive->surface_pressure.mbar);
+	dive = get_dive(1);
+	QVERIFY(dive != NULL);
+	dive->selected = true;
+	QCOMPARE(991, dive->surface_pressure.mbar);
+}
+
+void TestAirPressure::testConvertAltitudetoAirPressure()
+{
+	QCOMPARE(891,altitude_to_pressure(1000000)); // 1000 m altitude in mm
+	QCOMPARE(1013,altitude_to_pressure(0)); // sea level
+}
+
+void TestAirPressure::testWriteReadBackAirPressure()
+{
+	struct dive *dive;
+	int32_t ap = 1111;
+	dive = get_dive(0);
+	QVERIFY(dive != NULL);
+	dive->selected = true;
+	dive->surface_pressure.mbar = ap;
+	QCOMPARE(save_dives("./testout.ssrf"), 0);
+	clear_dive_file_data();
+	QCOMPARE(parse_file("./testout.ssrf", &dive_table, &trip_table, &dive_site_table), 0);
+	dive = get_dive(0);
+	QVERIFY(dive != NULL);
+	dive->selected = true;
+	QCOMPARE(ap, dive->surface_pressure.mbar);
+}
+
+QTEST_GUILESS_MAIN(TestAirPressure)
diff --git a/tests/testAirPressure.h b/tests/testAirPressure.h
new file mode 100644
index 000000000..18544eb47
--- /dev/null
+++ b/tests/testAirPressure.h
@@ -0,0 +1,19 @@
+// SPDX-License-Identifier: GPL-2.0
+#ifndef TESTPICTURE_H
+#define TESTPICTURE_H
+
+#include <QtTest>
+
+class TestAirPressure : public QObject {
+	Q_OBJECT
+private slots:
+	void initTestCase();
+	void get_dives();
+	void testReadAirPressure();
+	void testWriteReadBackAirPressure();
+	void testConvertAltitudetoAirPressure();
+};
+
+#endif
+
+