Add analogue stick support for controllers in SDL2

Former-commit-id: b3ccff53ded59930a0fe997f1bbbf83fd5e356d8
Former-commit-id: c3c286d1fccf6d9fc5478cd9f6b13d6a7d670b4b

platform/rustboyadvance-sdl2/src/input.rs

@@ -1,5 +1,6 @@
-use sdl2::keyboard::Scancode;
+use sdl2::controller::Axis;
 use sdl2::controller::Button;
+use sdl2::keyboard::Scancode;
 
 use rustboyadvance_core::keypad as gba_keypad;
 use rustboyadvance_core::InputInterface;
@@ -9,11 +10,12 @@ use bit::BitIndex;
 
 pub struct Sdl2Input {
     keyinput: u16,
+    axis_keyinput: u16,
 }
 
 impl InputInterface for Sdl2Input {
     fn poll(&mut self) -> u16 {
-        self.keyinput
+        !(!self.keyinput | !self.axis_keyinput)
     }
 }
 
@@ -41,6 +43,31 @@ impl Sdl2Input {
             self.keyinput.set_bit(key as usize, true);
         }
     }
+
+    pub fn on_axis_motion(&mut self, axis: Axis, val: i16) {
+        use gba_keypad::Keys as GbaKeys;
+        let keys = match axis {
+            Axis::LeftX => (GbaKeys::Left, GbaKeys::Right),
+            Axis::LeftY => (GbaKeys::Up, GbaKeys::Down),
+            Axis::TriggerLeft => (GbaKeys::ButtonL, GbaKeys::ButtonL),
+            Axis::TriggerRight => (GbaKeys::ButtonR, GbaKeys::ButtonR),
+            _ => {
+                return;
+            }
+        };
+
+        // Axis motion is an absolute value in the range
+        // [-32768, 32767]. Let's simulate a very rough dead
+        // zone to ignore spurious events.
+        let dead_zone = 10_000;
+        if val > dead_zone || val < -dead_zone {
+            let key = if val < 0 { keys.0 } else { keys.1 };
+            self.axis_keyinput.set_bit(key as usize, false);
+        } else {
+            self.axis_keyinput.set_bit(keys.0 as usize, true);
+            self.axis_keyinput.set_bit(keys.1 as usize, true);
+        }
+    }
 }
 
 fn scancode_to_keypad(scancode: Scancode) -> Option<gba_keypad::Keys> {
@@ -78,5 +105,6 @@ fn controller_button_to_keypad(button: Button) -> Option<gba_keypad::Keys> {
 pub fn create_input() -> Sdl2Input {
     Sdl2Input {
         keyinput: gba_keypad::KEYINPUT_ALL_RELEASED,
+        axis_keyinput: gba_keypad::KEYINPUT_ALL_RELEASED,
     }
 }

platform/rustboyadvance-sdl2/src/main.rs

@@ -193,7 +193,8 @@ fn main() -> Result<(), Box<dyn std::error::Error>> {
     canvas.set_logical_size(CANVAS_WIDTH, CANVAS_HEIGHT)?;
 
     let controller_subsystem = sdl_context.game_controller()?;
-    let controller_mappings = include_str!("../../../external/SDL_GameControllerDB/gamecontrollerdb.txt");
+    let controller_mappings =
+        include_str!("../../../external/SDL_GameControllerDB/gamecontrollerdb.txt");
     controller_subsystem.load_mappings_from_read(&mut Cursor::new(controller_mappings))?;
 
     let available_controllers = (0..controller_subsystem.num_joysticks()?)
@@ -205,11 +206,11 @@ fn main() -> Result<(), Box<dyn std::error::Error>> {
             let controller = controller_subsystem.open(id)?;
             info!("Found game controller: {}", controller.name());
             Some(controller)
-        },
+        }
         _ => {
             info!("No game controllers were found");
             None
-        },
+        }
     };
 
     let mut rom_path = match matches.value_of("game_rom") {
@@ -320,10 +321,13 @@ fn main() -> Result<(), Box<dyn std::error::Error>> {
                 },
                 Event::ControllerButtonDown { button, .. } => {
                     input.borrow_mut().on_controller_button_down(button);
-                },
+                }
                 Event::ControllerButtonUp { button, .. } => {
                     input.borrow_mut().on_controller_button_up(button);
-                },
+                }
+                Event::ControllerAxisMotion { axis, value, .. } => {
+                    input.borrow_mut().on_axis_motion(axis, value);
+                }
                 Event::Quit { .. } => break 'running,
                 Event::DropFile { filename, .. } => {
                     // load the new rom