Initialize Fact QVariant as invalid

src/FactSystem/Fact.cc

@@ -321,14 +321,18 @@ QStringList Fact::selectedBitmaskStrings() const
 
 QString Fact::_variantToString(const QVariant &variant, int decimalPlaces) const
 {
+    if (!variant.isValid()) {
+        return invalidValueString(decimalPlaces);
+    }
+
     QString valueString;
 
     switch (type()) {
     case FactMetaData::valueTypeFloat:
     {
         const float fValue = variant.toFloat();
         if (qIsNaN(fValue)) {
-            valueString = QStringLiteral("--.--");
+            valueString = invalidValueString(decimalPlaces);
         } else {
             valueString = QStringLiteral("%1").arg(fValue, 0, 'f', decimalPlaces);
         }
@@ -338,7 +342,7 @@ QString Fact::_variantToString(const QVariant &variant, int decimalPlaces) const
     {
         const double dValue = variant.toDouble();
         if (qIsNaN(dValue)) {
-            valueString = QStringLiteral("--.--");
+            valueString = invalidValueString(decimalPlaces);
         } else {
             valueString = QStringLiteral("%1").arg(dValue, 0, 'f', decimalPlaces);
         }
@@ -351,7 +355,7 @@ QString Fact::_variantToString(const QVariant &variant, int decimalPlaces) const
     {
         const double dValue = variant.toDouble();
         if (qIsNaN(dValue)) {
-            valueString = QStringLiteral("--:--:--");
+            valueString = invalidValueString(decimalPlaces);
         } else {
             QTime time(0, 0, 0, 0);
             time = time.addSecs(dValue);
@@ -367,6 +371,22 @@ QString Fact::_variantToString(const QVariant &variant, int decimalPlaces) const
     return valueString;
 }
 
+QString Fact::invalidValueString(int decimalPlaces) const {
+    switch (type()) {
+    case FactMetaData::valueTypeFloat:
+    case FactMetaData::valueTypeDouble:
+        if (decimalPlaces <= 0) {
+            return QStringLiteral("--");
+        }
+        return QStringLiteral("--.") +
+               QString(decimalPlaces, QLatin1Char('-'));
+    case FactMetaData::valueTypeElapsedTimeInSeconds:
+        return QStringLiteral("--:--:--");
+    default:
+        return QStringLiteral("--");
+    }
+}
+
 QString Fact::rawValueStringFullPrecision() const
 {
     return _variantToString(rawValue(), 18);

src/FactSystem/Fact.h

@@ -56,6 +56,7 @@ class Fact : public QObject
     Q_PROPERTY(QVariant     value                   READ cookedValue                WRITE setCookedValue        NOTIFY valueChanged)
     Q_PROPERTY(QVariant     rawValue                READ rawValue                   WRITE setRawValue           NOTIFY rawValueChanged)
     Q_PROPERTY(bool         valueEqualsDefault      READ valueEqualsDefault                                     NOTIFY valueChanged)
+    Q_PROPERTY(QString      invalidValueString      READ invalidValueString                                     CONSTANT)
     Q_PROPERTY(QString      valueString             READ cookedValueString                                      NOTIFY valueChanged)
     Q_PROPERTY(QString      enumOrValueString       READ enumOrValueString                                      NOTIFY valueChanged)
     Q_PROPERTY(double       increment               READ cookedIncrement                                        CONSTANT)
@@ -116,6 +117,8 @@ class Fact : public QObject
     FactMetaData::ValueType_t type() const { return _type; }
     QString cookedUnits() const;
     QString rawUnits() const;
+    QString invalidValueString(int decimalPlaces) const;
+    QString invalidValueString() const { return invalidValueString(decimalPlaces()); }
     QString rawValueString() const;
     QString cookedValueString() const;
     bool valueEqualsDefault() const;
@@ -191,7 +194,7 @@ class Fact : public QObject
 
     QString _name;
     int _componentId = -1;
-    QVariant _rawValue = 0;
+    QVariant _rawValue; // QVariant::Invalid
     FactMetaData::ValueType_t _type = FactMetaData::valueTypeInt32;
     FactMetaData *_metaData = nullptr;
     bool _sendValueChangedSignals = true;

src/QmlControls/InstrumentValueValue.qml

@@ -43,7 +43,7 @@ ColumnLayout {
             if (instrumentValueData.fact) {
                 return instrumentValueData.fact.enumOrValueString + (instrumentValueData.showUnits ? " " + instrumentValueData.fact.units : "")
             } else {
-                return qsTr("--.--")
+                return qsTr("--")
             }
         }
     }

src/UI/toolbar/EscIndicatorPage.qml

@@ -20,7 +20,7 @@ ToolIndicatorPage {
 
     property var    activeVehicle:  QGroundControl.multiVehicleManager.activeVehicle
     property string na:             qsTr("N/A", "No data to display")
-    property string valueNA:        qsTr("--.--", "No data to display")
+    property string valueNA:        qsTr("--", "No data to display")
 
     property var    _escs:          activeVehicle ? activeVehicle.escs : null
     property int    _onlineBitmask: _escs ? _escs.get(0).info.rawValue : 0

src/Vehicle/FactGroups/VehicleFactGroup.cc

@@ -49,7 +49,7 @@ VehicleFactGroup::VehicleFactGroup(QObject *parent)
     _addFact(&_throttlePctFact);
     _addFact(&_imuTempFact);
 
-    _hobbsFact.setRawValue(QStringLiteral("0000:00:00"));
+    _hobbsFact.setRawValue(QStringLiteral("----:--:--"));
 }
 
 void VehicleFactGroup::handleMessage(Vehicle *vehicle, const mavlink_message_t &message)

src/Vehicle/Vehicle.cc

@@ -256,9 +256,6 @@ void Vehicle::_commonInit(LinkInterface* link)
     connect(this, &Vehicle::homePositionChanged,    this, &Vehicle::_updateDistanceHeadingHome);
     connect(this, &Vehicle::hobbsMeterChanged,      this, &Vehicle::_updateHobbsMeter);
     connect(this, &Vehicle::coordinateChanged,      this, &Vehicle::_updateAltAboveTerrain);
-    // Initialize alt above terrain to Nan so frontend can display it correctly in case the terrain query had no response
-    _altitudeAboveTerrFact.setRawValue(qQNaN());
-
     connect(this, &Vehicle::vehicleTypeChanged,     this, &Vehicle::inFwdFlightChanged);
     connect(this, &Vehicle::vtolInFwdFlightChanged, this, &Vehicle::inFwdFlightChanged);
 
@@ -351,8 +348,6 @@ void Vehicle::_commonInit(LinkInterface* link)
         }
     }
 
-    _flightDistanceFact.setRawValue(0);
-    _flightTimeFact.setRawValue(0);
     _flightTimeUpdater.setInterval(1000);
     _flightTimeUpdater.setSingleShot(false);
     connect(&_flightTimeUpdater, &QTimer::timeout, this, &Vehicle::_updateFlightTime);