PX4 Autopilot plugin: Allow horizon level calibration

src/AutoPilotPlugins/PX4/SensorsComponent.qml

@@ -43,7 +43,8 @@ QGCView {
     readonly property string compassHelp:   "For Compass calibration you will need to rotate your vehicle through a number of positions. For this calibration it is best " +
                                                 "to be connected to your vehicle via radio instead of USB, since the USB cable will likely get in the way."
     readonly property string gyroHelp:      "For Gyroscope calibration you will need to place your vehicle right side up on solid surface and leave it still."
-    readonly property string accelHelp:     "For Accelerometer calibration you will need to place your vehicle on all six sides and hold it still in each orientation for a few seconds."
+    readonly property string accelHelp:     "For Accelerometer calibration you will need to place your vehicle on all six sides on a level surface and hold it still in each orientation for a few seconds."
+    readonly property string levelHelp:     "To level the horizon you need to place the vehicle in its level flight position."
     readonly property string airspeedHelp:  "For Airspeed calibration you will need to keep your airspeed sensor out of any wind and then blow across the sensor."
 
     readonly property string statusTextAreaDefaultText: compassHelp + "\n\n" + gyroHelp + "\n\n" + accelHelp + "\n\n" + airspeedHelp + "\n\n"
@@ -128,6 +129,8 @@ QGCView {
                     controller.calibrateGyro()
                 } else if (preCalibrationDialogType == "accel") {
                     controller.calibrateAccel()
+                } else if (preCalibrationDialogType == "level") {
+                    controller.calibrateLevel()
                 } else if (preCalibrationDialogType == "compass") {
                     controller.calibrateCompass()
                 } else if (preCalibrationDialogType == "airspeed") {
@@ -330,6 +333,21 @@ QGCView {
                         }
                     }
 
+                    IndicatorButton {
+                        property Fact fact: Fact { name: "SENS_BOARD_X_OFF" }
+
+                        id:             levelButton
+                        width:          parent.buttonWidth
+                        text:           "Level Horizon"
+                        indicatorGreen: fact.value != 0
+
+                        onClicked: {
+                            preCalibrationDialogType = "level"
+                            preCalibrationDialogHelp = levelHelp
+                            showDialog(preCalibrationDialogComponent, "Level Horizon", 50, StandardButton.Cancel | StandardButton.Ok)
+                        }
+                    }
+
                     IndicatorButton {
                         property Fact fact: Fact { name: "SENS_DPRES_OFF" }
 

src/AutoPilotPlugins/PX4/SensorsComponentController.cc

@@ -191,6 +191,12 @@ void SensorsComponentController::calibrateAccel(void)
     _uas->startCalibration(UASInterface::StartCalibrationAccel);
 }
 
+void SensorsComponentController::calibrateLevel(void)
+{
+    _startLogCalibration();
+    _uas->startCalibration(UASInterface::StartCalibrationLevel);
+}
+
 void SensorsComponentController::calibrateAirspeed(void)
 {
     _startLogCalibration();

src/AutoPilotPlugins/PX4/SensorsComponentController.h

@@ -85,6 +85,7 @@ public:
     Q_INVOKABLE void calibrateCompass(void);
     Q_INVOKABLE void calibrateGyro(void);
     Q_INVOKABLE void calibrateAccel(void);
+    Q_INVOKABLE void calibrateLevel(void);
     Q_INVOKABLE void calibrateAirspeed(void);
     Q_INVOKABLE void cancelCalibration(void);