GuidedActions: fix incorrect slider value conversion

[or-rhssk]

Description

The floating point value got converted to a string, which in turn broke arithmetic in GuidedActionsController (e.g. Vehicle::guidedModeOrbit always received NAN as altitude).

Checklist:

• Review Contribution Guidelines.
• Review Code of Conduct.
• I have tested my changes.

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[DonLakeFlyer]

I don't see how this is getting a NaN. I tried to reproduct a problem with guided orbit using px4 sitl and it worked fine. It went tot he correct altitude I set. How do you reproduce this?

[or-rhssk]

Weird, just tried with fresh QGC (1e99268) and PX4 (81552fc036 / gazebo-classic_iris), altitude doesn't change after entering orbit.

orbit-altitude.mp4

Here's debug output after applying this patch:

diff --git a/src/FlightDisplay/GuidedActionsController.qml b/src/FlightDisplay/GuidedActionsController.qml
index 881742c73..0e808d820 100644
--- a/src/FlightDisplay/GuidedActionsController.qml
+++ b/src/FlightDisplay/GuidedActionsController.qml
@@ -626,7 +626,9 @@ Item {
             _activeVehicle.setCurrentMissionSequence(actionData)
             break
         case actionOrbit:
+            console.log("sliderOutputValue: " + sliderOutputValue + " / " + typeof sliderOutputValue);
             var valueInMeters = _unitsConversion.appSettingsVerticalDistanceUnitsToMeters(sliderOutputValue)
+            console.log("valueInMeters: " + valueInMeters + " / " + typeof valueInMeters);
             _activeVehicle.guidedModeOrbit(orbitMapCircle.center, orbitMapCircle.radius() * (orbitMapCircle.clockwiseRotation ? 1 : -1), _activeVehicle.altitudeRelative.rawValue + valueInMeters)
             break
         case actionLandAbort:
diff --git a/src/Vehicle/Vehicle.cc b/src/Vehicle/Vehicle.cc
index a5b7d963f..2ce200332 100644
--- a/src/Vehicle/Vehicle.cc
+++ b/src/Vehicle/Vehicle.cc
@@ -2168,6 +2168,7 @@ Vehicle::guidedModeChangeEquivalentAirspeedMetersSecond(double airspeed)
 
 void Vehicle::guidedModeOrbit(const QGeoCoordinate& centerCoord, double radius, double amslAltitude)
 {
+    qInfo() << "Vehicle::guidedModeOrbit: amslAltitude:" << amslAltitude;
     if (!orbitModeSupported()) {
         qgcApp()->showAppMessage(QStringLiteral("Orbit mode not supported by Vehicle."));
         return;

Before PR:

qml: sliderOutputValue: 121.9 / string
qml: valueInMeters: 121.9 / string
Vehicle::guidedModeOrbit: amslAltitude: nan

After PR:

qml: sliderOutputValue: 121.92 / number
qml: valueInMeters: 121.92 / number
Vehicle::guidedModeOrbit: amslAltitude: 125.171

[or-rhssk]

For me this fixes the "nan-as-AMSL" but there appears to be another issue.

After 404324d this can happen:

• vehicle takes off from 500m AMSL to 510m AMSL (10m relative altitude),
• user executes orbit with slider value of 120m,
• Vehicle::guidedModeOrbit sends 120 + 10 = 130m AMSL altitude to PX4 (well below ground).

[DonLakeFlyer]

Yeah, you are right. I finally got the same NaN thing you are seeing. I'm trying to figure out what is going on with PX4 and orbit altitude, It doesn't respect MAV_FRAME as far as I can tell. Asking the px4 devs.

[DonLakeFlyer]

Replaced by other pull