Fix altitude slider and guidedactions for speed action:

There were some errors where fixed wing would not show the action,
also unit conversion support for speed was added

src/FlightDisplay/GuidedActionsController.qml

@@ -190,22 +190,24 @@ Item {
     function setupSlider(actionCode) {
         // generic defaults
         guidedValueSlider.configureAsLinearSlider()
+        guidedValueSlider.setIsSpeedSlider(false)
 
         if (actionCode === actionTakeoff) {
                 guidedValueSlider.setMinVal(_activeVehicle.minimumTakeoffAltitude())
                 guidedValueSlider.setValue(_activeVehicle ? _activeVehicle.minimumTakeoffAltitude() : 0)
                 guidedValueSlider.setDisplayText("Height")
         } else if (actionCode === actionChangeSpeed) {
-            if (_activeVehicle.vtolInFwdFlight) {
+            guidedValueSlider.setIsSpeedSlider(true)
+            if (_fixedWing) {
                 guidedValueSlider.setDisplayText("Set Airspeed")
-                guidedValueSlider.setMinVal(_activeVehicle.minimumEquivalentAirspeed())
-                guidedValueSlider.setMaxVal(_activeVehicle.maximumEquivalentAirspeed())
-                guidedValueSlider.setValue(_activeVehicle.airSpeedSetpoint.rawValue)
-            } else {
+                guidedValueSlider.setMinVal(QGroundControl.unitsConversion.metersSecondToAppSettingsSpeedUnits(_activeVehicle.minimumEquivalentAirspeed()).toFixed(1))
+                guidedValueSlider.setMaxVal(QGroundControl.unitsConversion.metersSecondToAppSettingsSpeedUnits(_activeVehicle.maximumEquivalentAirspeed()).toFixed(1))
+                guidedValueSlider.setValue(_activeVehicle.airSpeed.value)
+            } else if (!_fixedWing && _activeVehicle.haveMRSpeedLimits) {
                 guidedValueSlider.setDisplayText("Set Speed")
-                guidedValueSlider.setMinVal(0.1)
-                guidedValueSlider.setMaxVal(_activeVehicle.maximumHorizontalSpeedMultirotor())
-                guidedValueSlider.setValue(_activeVehicle.maximumHorizontalSpeedMultirotor()/2)
+                guidedValueSlider.setMinVal(QGroundControl.unitsConversion.metersSecondToAppSettingsSpeedUnits(0.1).toFixed(1))
+                guidedValueSlider.setMaxVal(QGroundControl.unitsConversion.metersSecondToAppSettingsSpeedUnits(_activeVehicle.maximumHorizontalSpeedMultirotor()).toFixed(1))
+                guidedValueSlider.setValue(QGroundControl.unitsConversion.metersSecondToAppSettingsSpeedUnits(_activeVehicle.maximumHorizontalSpeedMultirotor()/2).toFixed(1))
             }
         } else if (actionCode === actionChangeAlt || actionCode === actionOrbit || actionCode === actionGoto || actionCode === actionPause) {
             guidedValueSlider.setDisplayText("New Alt(rel)")
@@ -599,10 +601,12 @@ Item {
             break
         case actionChangeSpeed:
             if (_activeVehicle) {
+                // We need to convert back to m/s as that is what mavlink standard uses for MAV_CMD_DO_CHANGE_SPEED
+                var metersSecondSpeed = QGroundControl.unitsConversion.appSettingsSpeedUnitsToMetersSecond(sliderOutputValue).toFixed(1)
                 if (_activeVehicle.vtolInFwdFlight || _activeVehicle.fixedWing) {
-                   _activeVehicle.guidedModeChangeEquivalentAirspeed(sliderOutputValue)
+                   _activeVehicle.guidedModeChangeEquivalentAirspeed(metersSecondSpeed)
                 } else {
-                    _activeVehicle.guidedModeChangeGroundSpeed(sliderOutputValue)
+                    _activeVehicle.guidedModeChangeGroundSpeed(metersSecondSpeed)
                 }
             }
             break

src/FlightDisplay/GuidedValueSlider.qml

@@ -26,6 +26,7 @@ Rectangle {
     property real _sliderCenterValue:   _vehicleAltitude
     property string _displayText:       ""
     property bool _altSlider:         true
+    property bool _speedSlider:       false
 
     property var sliderValue : valueSlider.value
 
@@ -75,6 +76,10 @@ Rectangle {
         _displayText = text
     }
 
+    function setIsSpeedSlider(isSpeed) {
+        _speedSlider = isSpeed
+    }
+
     function getOutputValue() {
         if (_altSlider) {
             return valueField.newValue - _sliderCenterValue
@@ -101,7 +106,8 @@ Rectangle {
         QGCLabel {
             id:                         valueField
             anchors.horizontalCenter:   parent.horizontalCenter
-            text:                       newValueAppUnits + " " + QGroundControl.unitsConversion.appSettingsHorizontalDistanceUnitsString
+            text:                       newValueAppUnits + " " + (_speedSlider ? QGroundControl.unitsConversion.appSettingsSpeedUnitsString
+                                                                               : QGroundControl.unitsConversion.appSettingsHorizontalDistanceUnitsString)
 
             property real   newValue
             property string newValueAppUnits
@@ -120,7 +126,12 @@ Rectangle {
             function updateLinear(value) {
                 // value is between -1 and 1
                 newValue = _sliderMinVal + (value + 1) * 0.5 * (_sliderMaxVal - _sliderMinVal)
-                newValueAppUnits = QGroundControl.unitsConversion.metersToAppSettingsHorizontalDistanceUnits(newValue).toFixed(1)
+                if (_speedSlider) {
+                    // Already working in converted units
+                    newValueAppUnits = newValue.toFixed(1)
+                } else {
+                    newValueAppUnits = QGroundControl.unitsConversion.metersToAppSettingsHorizontalDistanceUnits(newValue).toFixed(1)
+                }
             }
 
             function getSliderValueFromOutputLinear(val) {