AP_Common: Location: add set_alt_m

libraries/AP_Common/Location.h

@@ -35,6 +35,10 @@ class Location
 
     // set altitude
     void set_alt_cm(int32_t alt_cm, AltFrame frame);
+    // set_alt_m - set altitude in metres
+    void set_alt_m(float alt_m, AltFrame frame) {
+        set_alt_cm(alt_m*100, frame);
+    }
 
     // get altitude (in cm) in the desired frame
     // returns false on failure to get altitude in the desired frame which can only happen if the original frame or desired frame is:

libraries/AP_Common/tests/test_location.cpp

@@ -280,6 +280,13 @@ TEST(Location, Tests)
     EXPECT_EQ(0, test_location4.loiter_xtrack);
     EXPECT_TRUE(test_location4.initialised());
 
+    // test set_alt_m API:
+    Location loc = test_home;
+    loc.set_alt_m(1.71, Location::AltFrame::ABSOLUTE);
+    int32_t alt_in_cm_from_m;
+    EXPECT_TRUE(loc.get_alt_cm(Location::AltFrame::ABSOLUTE, alt_in_cm_from_m));
+    EXPECT_EQ(171, alt_in_cm_from_m);
+
     // can't create a Location using a vector here as there's no origin for the vector to be relative to:
     // const Location test_location_empty{test_vect, Location::AltFrame::ABOVE_HOME};
     // EXPECT_FALSE(test_location_empty.get_vector_from_origin_NEU(test_vec3));

libraries/GCS_MAVLink/GCS_Common.cpp

@@ -5058,7 +5058,7 @@ bool GCS_MAVLINK::location_from_command_t(const mavlink_command_int_t &in, Locat
     out.lat = in.x;
     out.lng = in.y;
 
-    out.set_alt_cm(int32_t(in.z * 100), frame);
+    out.set_alt_m(in.z, frame);
 
     return true;
 }