GCS_MAVLink: use compass singleton instead of subclass callback

libraries/GCS_MAVLink/GCS.h

@@ -254,7 +254,6 @@ protected:
     virtual bool accept_packet(const mavlink_status_t &status, mavlink_message_t &msg) { return true; }
     virtual AP_Mission *get_mission() = 0;
     virtual AP_Rally *get_rally() const = 0;
-    virtual Compass *get_compass() const = 0;
     virtual class AP_Camera *get_camera() const = 0;
     virtual AP_AdvancedFailsafe *get_advanced_failsafe() const { return nullptr; };
     virtual AP_VisualOdom *get_visual_odom() const { return nullptr; }

libraries/GCS_MAVLink/GCS_Common.cpp

@@ -2538,10 +2538,7 @@ MAV_RESULT GCS_MAVLINK::handle_command_flash_bootloader(const mavlink_command_lo
 
 MAV_RESULT GCS_MAVLINK::handle_command_preflight_set_sensor_offsets(const mavlink_command_long_t &packet)
 {
-    Compass *compass = get_compass();
-    if (compass == nullptr) {
-        return MAV_RESULT_UNSUPPORTED;
-    }
+    Compass &compass = AP::compass();
 
     uint8_t compassNumber = -1;
     if (is_equal(packet.param1, 2.0f)) {
@@ -2554,7 +2551,7 @@ MAV_RESULT GCS_MAVLINK::handle_command_preflight_set_sensor_offsets(const mavlin
     if (compassNumber == (uint8_t) -1) {
         return MAV_RESULT_FAILED;
     }
-    compass->set_and_save_offsets(compassNumber, packet.param2, packet.param3, packet.param4);
+    compass.set_and_save_offsets(compassNumber, packet.param2, packet.param3, packet.param4);
     return MAV_RESULT_ACCEPTED;
 }
 
@@ -2640,11 +2637,7 @@ MAV_RESULT GCS_MAVLINK::handle_command_preflight_calibration(const mavlink_comma
 
 MAV_RESULT GCS_MAVLINK::handle_command_mag_cal(const mavlink_command_long_t &packet)
 {
-    Compass *compass = get_compass();
-    if (compass == nullptr) {
-        return MAV_RESULT_UNSUPPORTED;
-    }
-    return compass->handle_mag_cal_command(packet);
+    return AP::compass().handle_mag_cal_command(packet);
 }
 
 MAV_RESULT GCS_MAVLINK::handle_command_request_autopilot_capabilities(const mavlink_command_long_t &packet)
@@ -2845,18 +2838,15 @@ void GCS_MAVLINK::handle_command_int(mavlink_message_t *msg)
 
 bool GCS_MAVLINK::try_send_compass_message(const enum ap_message id)
 {
-    Compass *compass = get_compass();
-    if (compass == nullptr) {
-        return true;
-    }
+    Compass &compass = AP::compass();
     bool ret = true;
     switch (id) {
     case MSG_MAG_CAL_PROGRESS:
-        compass->send_mag_cal_progress(chan);
+        compass.send_mag_cal_progress(chan);
         ret = true;;
         break;
     case MSG_MAG_CAL_REPORT:
-        compass->send_mag_cal_report(chan);
+        compass.send_mag_cal_report(chan);
         ret = true;
         break;
     default:

libraries/GCS_MAVLink/GCS_Dummy.h

@@ -22,7 +22,6 @@ class GCS_MAVLINK_Dummy : public GCS_MAVLINK
 
 protected:
 
-    Compass *get_compass() const override { return nullptr; };
     AP_Mission *get_mission() override { return nullptr; }
     AP_Rally *get_rally() const override { return nullptr; };
     AP_Camera *get_camera() const override { return nullptr; };

libraries/GCS_MAVLink/examples/routing/routing.cpp

@@ -28,7 +28,6 @@ public:
 protected:
 
     uint32_t telem_delay() const override { return 0; }
-    Compass *get_compass() const override { return nullptr; };
     AP_Mission *get_mission() override { return nullptr; }
     AP_Rally *get_rally() const override { return nullptr; }
     AP_Camera *get_camera() const override { return nullptr; };