Joystick: make negativethrust visible by firmwarePlugin

src/FirmwarePlugin/FirmwarePlugin.cc

@@ -129,6 +129,12 @@ bool FirmwarePlugin::supportsThrottleModeCenterZero(void)
     return true;
 }
 
+bool FirmwarePlugin::supportsNegativeThrust(void)
+{
+    // By default, this is not supported
+    return false;
+}
+
 bool FirmwarePlugin::supportsManualControl(void)
 {
     return false;

src/FirmwarePlugin/FirmwarePlugin.h

@@ -158,6 +158,10 @@ public:
     /// throttle.
     virtual bool supportsThrottleModeCenterZero(void);
 
+    /// Returns true if the vehicle and firmware supports the use of negative thrust
+    /// Typically supported rover.
+    virtual bool supportsNegativeThrust(void);
+
     /// Returns true if the firmware supports the use of the MAVlink "MANUAL_CONTROL" message.
     /// By default, this returns false unless overridden in the firmware plugin.
     virtual bool supportsManualControl(void);

src/Joystick/Joystick.cc

@@ -463,7 +463,7 @@ void Joystick::run(void)
 
             // Adjust throttle to 0:1 range
             if (_throttleMode == ThrottleModeCenterZero && _activeVehicle->supportsThrottleModeCenterZero()) {
-                if (!_negativeThrust) {
+                if (!_activeVehicle->supportsNegativeThrust() || !_negativeThrust) {
                     throttle = std::max(0.0f, throttle);
                 }
             } else {

src/Vehicle/Vehicle.cc

@@ -2118,6 +2118,11 @@ bool Vehicle::supportsThrottleModeCenterZero(void) const
     return _firmwarePlugin->supportsThrottleModeCenterZero();
 }
 
+bool Vehicle::supportsNegativeThrust(void) const
+{
+    return _firmwarePlugin->supportsNegativeThrust();
+}
+
 bool Vehicle::supportsRadio(void) const
 {
     return _firmwarePlugin->supportsRadio();

src/Vehicle/Vehicle.h

@@ -284,6 +284,7 @@ public:
     Q_PROPERTY(bool                 sub                     READ sub                                                    NOTIFY vehicleTypeChanged)
     Q_PROPERTY(bool                 supportsManualControl   READ supportsManualControl                                  CONSTANT)
     Q_PROPERTY(bool        supportsThrottleModeCenterZero   READ supportsThrottleModeCenterZero                         CONSTANT)
+    Q_PROPERTY(bool                supportsNegativeThrust   READ supportsNegativeThrust                                 CONSTANT)
     Q_PROPERTY(bool                 supportsJSButton        READ supportsJSButton                                       CONSTANT)
     Q_PROPERTY(bool                 supportsRadio           READ supportsRadio                                          CONSTANT)
     Q_PROPERTY(bool               supportsMotorInterference READ supportsMotorInterference                              CONSTANT)
@@ -522,6 +523,7 @@ public:
 
     bool supportsManualControl(void) const;
     bool supportsThrottleModeCenterZero(void) const;
+    bool supportsNegativeThrust(void) const;
     bool supportsRadio(void) const;
     bool supportsJSButton(void) const;
     bool supportsMotorInterference(void) const;

src/VehicleSetup/JoystickConfig.qml

@@ -455,6 +455,7 @@ SetupPage {
                                 }
 
                                 QGCCheckBox {
+                                    visible:        _activeVehicle.supportsNegativeThrust
                                     id:             negativeThrust
                                     text:           qsTr("Allow negative Thrust")
                                     checked:        _activeJoystick ? _activeJoystick.negativeThrust : false