AP_HAL_SITL: Support SFML joystick input

libraries/AP_HAL_SITL/RCInput.cpp

@@ -5,6 +5,14 @@
 #include <SITL/SITL.h>
 #include <AP_RCProtocol/AP_RCProtocol.h>
 
+#ifdef SFML_JOYSTICK
+  #ifdef HAVE_SFML_GRAPHICS_HPP
+    #include <SFML/Window/Joystick.hpp>
+  #elif HAVE_SFML_GRAPHIC_H
+    #include <SFML/Window/Joystick.h>
+  #endif
+#endif // SFML_JOYSTICK
+
 using namespace HALSITL;
 
 extern const AP_HAL::HAL& hal;
@@ -39,7 +47,22 @@ uint16_t RCInput::read(uint8_t ch)
     if (ch >= num_channels()) {
         return 0;
     }
+#ifdef SFML_JOYSTICK
+    SITL::SITL *_sitl = AP::sitl();
+    if (_sitl) {
+        const sf::Joystick::Axis axis = sf::Joystick::Axis(_sitl->sfml_joystick_axis[ch].get());
+        const unsigned int stickID = _sitl->sfml_joystick_id;
+        if (sf::Joystick::hasAxis(stickID, axis)) {
+            return (constrain_float(sf::Joystick::getAxisPosition(stickID, axis) + 100, 0, 200) * 5) + 1000;
+        } else {
+            return 0;
+        }
+    } else {
+      return 0;
+    }
+#else
     return _sitlState->pwm_input[ch];
+#endif
 }
 
 uint8_t RCInput::read(uint16_t* periods, uint8_t len)
@@ -60,7 +83,11 @@ uint8_t RCInput::num_channels()
     }
     SITL::SITL *_sitl = AP::sitl();
     if (_sitl) {
+#ifdef SFML_JOYSTICK
+        return (sf::Joystick::isConnected(_sitl->sfml_joystick_id.get())) ? ARRAY_SIZE(_sitl->sfml_joystick_axis) : 0;
+#else
         return MIN(_sitl->rc_chancount.get(), SITL_RC_INPUT_CHANNELS);
+#endif // SFML_JOYSTICK
     }
     return SITL_RC_INPUT_CHANNELS;
 }