Handle parameters not being available

src/AutoPilotPlugins/PX4/SensorsComponent.qml

@@ -272,16 +272,6 @@ Rectangle {
             }
 
             Column {
-                property Fact cal_mag0_rot: Fact { name: "CAL_MAG0_ROT" }
-                property Fact cal_mag1_rot: Fact { name: "CAL_MAG1_ROT" }
-                property Fact cal_mag2_rot: Fact { name: "CAL_MAG2_ROT" }
-
-                // Compass rotation parameter < 0 indicates either internal compass, or no compass. So in
-                // both those cases we do not show a rotation combo.
-                property bool showCompass0: cal_mag0_rot.value >= 0
-                property bool showCompass1: cal_mag1_rot.value >= 0
-                property bool showCompass2: cal_mag2_rot.value >= 0
-
                 x: parent.width - rotationColumnWidth
 
                 QGCLabel { text: "Autpilot Orientation" }
@@ -309,8 +299,8 @@ Rectangle {
                         fact:   Fact { name: "CAL_MAG0_ROT" }
                     }
                 }
-                Loader { sourceComponent: parent.showCompass0 ? compass0ComponentLabel : null }
-                Loader { sourceComponent: parent.showCompass0 ? compass0ComponentCombo : null }
+                Loader { sourceComponent: controller.showCompass0 ? compass0ComponentLabel : null }
+                Loader { sourceComponent: controller.showCompass0 ? compass0ComponentCombo : null }
 
                 // Compass 1 rotation
                 Component {
@@ -328,8 +318,8 @@ Rectangle {
                         fact:   Fact { name: "CAL_MAG1_ROT" }
                     }
                 }
-                Loader { sourceComponent: parent.showCompass1 ? compass1ComponentLabel : null }
-                Loader { sourceComponent: parent.showCompass1 ? compass1ComponentCombo : null }
+                Loader { sourceComponent: controller.showCompass1 ? compass1ComponentLabel : null }
+                Loader { sourceComponent: controller.showCompass1 ? compass1ComponentCombo : null }
 
                 // Compass 2 rotation
                 Component {
@@ -347,8 +337,8 @@ Rectangle {
                         fact:   Fact { name: "CAL_MAG2_ROT" }
                     }
                 }
-                Loader { sourceComponent: parent.showCompass2 ? compass2ComponentLabel : null }
-                Loader { sourceComponent: parent.showCompass2 ? compass2ComponentCombo : null }
+                Loader { sourceComponent: controller.showCompass2 ? compass2ComponentLabel : null }
+                Loader { sourceComponent: controller.showCompass2 ? compass2ComponentCombo : null }
             }
         }
     }

src/AutoPilotPlugins/PX4/SensorsComponentController.cc

@@ -38,6 +38,9 @@ SensorsComponentController::SensorsComponentController(AutoPilotPlugin* autopilo
     _progressBar(NULL),
     _showGyroCalArea(false),
     _showAccelCalArea(false),
+    _showCompass0(false),
+    _showCompass1(false),
+    _showCompass2(false),
     _gyroCalInProgress(false),
     _accelCalDownSideDone(false),
     _accelCalUpsideDownSideDone(false),
@@ -54,7 +57,16 @@ SensorsComponentController::SensorsComponentController(AutoPilotPlugin* autopilo
     _textLoggingStarted(false),
     _autopilot(autopilot)
 {
-    Q_ASSERT(autopilot);
+    Q_ASSERT(_autopilot);
+    Q_ASSERT(_autopilot->pluginReady());
+    
+    // Mag rotation parameters are optional
+    _showCompass0 = _autopilot->parameterExists("CAL_MAG0_ROT") &&
+                        _autopilot->getParameterFact("CAL_MAG0_ROT")->value().toInt() >= 0;
+    _showCompass1 = _autopilot->parameterExists("CAL_MAG1_ROT") &&
+                        _autopilot->getParameterFact("CAL_MAG1_ROT")->value().toInt() >= 0;
+    _showCompass2 = _autopilot->parameterExists("CAL_MAG2_ROT") &&
+                        _autopilot->getParameterFact("CAL_MAG2_ROT")->value().toInt() >= 0;
 }
 
 /// Appends the specified text to the status log area in the ui
@@ -273,11 +285,19 @@ void SensorsComponentController::_refreshParams(void)
     _autopilot->refreshParameter(FactSystem::defaultComponentId, "CAL_ACC0_ID");
     _autopilot->refreshParameter(FactSystem::defaultComponentId, "SENS_DPRES_OFF");
     
-    _autopilot->refreshParameter(FactSystem::defaultComponentId, "CAL_MAG0_ROT");
-    _autopilot->refreshParameter(FactSystem::defaultComponentId, "CAL_MAG1_ROT");
-    _autopilot->refreshParameter(FactSystem::defaultComponentId, "CAL_MAG2_ROT");
     _autopilot->refreshParameter(FactSystem::defaultComponentId, "SENS_BOARD_ROT");
     
+    // Mag rotation parameters are optional
+    if (_autopilot->parameterExists("CAL_MAG0_ROT")) {
+        _autopilot->refreshParameter(FactSystem::defaultComponentId, "CAL_MAG0_ROT");
+    }
+    if (_autopilot->parameterExists("CAL_MAG1_ROT")) {
+        _autopilot->refreshParameter(FactSystem::defaultComponentId, "CAL_MAG1_ROT");
+    }
+    if (_autopilot->parameterExists("CAL_MAG2_ROT")) {
+        _autopilot->refreshParameter(FactSystem::defaultComponentId, "CAL_MAG2_ROT");
+    }
+    
     // Pull full set in order to get all cal values back
     _autopilot->refreshAllParameters();
 }

src/AutoPilotPlugins/PX4/SensorsComponentController.h

@@ -51,6 +51,10 @@ public:
     Q_PROPERTY(QQuickItem* accelButton MEMBER _accelButton)
     Q_PROPERTY(QQuickItem* airspeedButton MEMBER _airspeedButton)
     
+    Q_PROPERTY(bool showCompass0 MEMBER _showCompass0 CONSTANT)
+    Q_PROPERTY(bool showCompass1 MEMBER _showCompass1 CONSTANT)
+    Q_PROPERTY(bool showCompass2 MEMBER _showCompass2 CONSTANT)
+    
     Q_PROPERTY(bool showGyroCalArea MEMBER _showGyroCalArea NOTIFY showGyroCalAreaChanged)
     Q_PROPERTY(bool showAccelCalArea MEMBER _showAccelCalArea NOTIFY showAccelCalAreaChanged)
     
@@ -110,6 +114,10 @@ private:
     bool _showGyroCalArea;
     bool _showAccelCalArea;
     
+    bool _showCompass0;
+    bool _showCompass1;
+    bool _showCompass2;
+    
     bool _gyroCalInProgress;
     
     bool _accelCalDownSideDone;