AC_Fence: Change logic to fence enable and sys_status reporting

libraries/AC_Fence/AC_Fence.cpp

@@ -18,7 +18,7 @@ const AP_Param::GroupInfo AC_Fence::var_info[] = {
     // @Description: Allows you to enable (1) or disable (0) the fence functionality
     // @Values: 0:Disabled,1:Enabled
     // @User: Standard
-    AP_GROUPINFO("ENABLE",      0,  AC_Fence,   _enabled,   0),
+    //AP_GROUPINFO("ENABLE",      0,  AC_Fence,   _enabled,   0),
 
     // @Param: TYPE
     // @DisplayName: Fence Type
@@ -159,13 +159,20 @@ void AC_Fence::disable_floor()
 
 bool AC_Fence::present() const
 {
-    // A fence is present if it is enabled and there are points present
-    if (_poly_loader.total_fence_count() == 0) {
-        return false;
-    }
+    // A fence is present if any of the conditions are true.
+    //   * tin can (circle) is enabled
+    //   * min or max alt is enabled
+    //   * polygon fences are enabled and any fence has been uploaded
+    if (_enabled_fences.get() & AC_FENCE_TYPE_CIRCLE ||
+        _enabled_fences.get() & AC_FENCE_TYPE_ALT_MIN ||
+        _enabled_fences.get() & AC_FENCE_TYPE_ALT_MAX ||
+        ((_enabled_fences.get() & AC_FENCE_TYPE_POLYGON) && _poly_loader.total_fence_count() > 0)) {
         return true;
     }
 
+    return false;
+}
+
 /// get_enabled_fences - returns bitmask of enabled fences
 uint8_t AC_Fence::get_enabled_fences() const
 {
@@ -598,7 +605,8 @@ bool AC_Fence::sys_status_enabled() const
     if (_action == AC_FENCE_ACTION_REPORT_ONLY) {
         return false;
     }
-    return true;
+    // Fence is only enabled when the flag is enabled
+    return _enabled;
 }
 
 bool AC_Fence::sys_status_failed() const

libraries/AC_Fence/AC_Fence.h

@@ -177,7 +177,6 @@ private:
     bool pre_arm_check_alt(const char* &fail_msg) const;
 
     // parameters
-    AP_Int8         _enabled;               // fence enable/disable control
     AP_Int8         _auto_enabled;          // top level flag for auto enabling fence
     AP_Int8         _enabled_fences;        // bit mask holding which fences are enabled
     AP_Int8         _action;                // recovery action specified by user
@@ -200,6 +199,7 @@ private:
     float           _circle_breach_distance;    // distance beyond the circular fence
 
     // other internal variables
+    bool            _enabled;               // fence enable/disable control
     bool            _floor_enabled;         // fence floor is enabled
     float           _home_distance;         // distance from home in meters (provided by main code)
     float           _curr_alt;