Implement controller support for the SDL2 frontend

.gitmodules

@@ -1,3 +1,6 @@
 [submodule "external/gba-suite"]
 	path = external/gba-suite
 	url = https://github.com/jsmolka/gba-suite.git
+[submodule "external/SDL_GameControllerDB"]
+	path = external/SDL_GameControllerDB
+	url = https://github.com/gabomdq/SDL_GameControllerDB

platform/rustboyadvance-sdl2/src/input.rs

@@ -1,4 +1,5 @@
 use sdl2::keyboard::Scancode;
+use sdl2::controller::Button;
 
 use rustboyadvance_core::keypad as gba_keypad;
 use rustboyadvance_core::InputInterface;
@@ -22,11 +23,24 @@ impl Sdl2Input {
             self.keyinput.set_bit(key as usize, false);
         }
     }
+
     pub fn on_keyboard_key_up(&mut self, scancode: Scancode) {
         if let Some(key) = scancode_to_keypad(scancode) {
             self.keyinput.set_bit(key as usize, true);
         }
     }
+
+    pub fn on_controller_button_down(&mut self, button: Button) {
+        if let Some(key) = controller_button_to_keypad(button) {
+            self.keyinput.set_bit(key as usize, false);
+        }
+    }
+
+    pub fn on_controller_button_up(&mut self, button: Button) {
+        if let Some(key) = controller_button_to_keypad(button) {
+            self.keyinput.set_bit(key as usize, true);
+        }
+    }
 }
 
 fn scancode_to_keypad(scancode: Scancode) -> Option<gba_keypad::Keys> {
@@ -45,6 +59,22 @@ fn scancode_to_keypad(scancode: Scancode) -> Option<gba_keypad::Keys> {
     }
 }
 
+fn controller_button_to_keypad(button: Button) -> Option<gba_keypad::Keys> {
+    match button {
+        Button::DPadUp => Some(gba_keypad::Keys::Up),
+        Button::DPadDown => Some(gba_keypad::Keys::Down),
+        Button::DPadLeft => Some(gba_keypad::Keys::Left),
+        Button::DPadRight => Some(gba_keypad::Keys::Right),
+        Button::A => Some(gba_keypad::Keys::ButtonB), // A and B are swapped compared to the SDL layout
+        Button::B => Some(gba_keypad::Keys::ButtonA),
+        Button::Start => Some(gba_keypad::Keys::Start),
+        Button::Back => Some(gba_keypad::Keys::Select),
+        Button::LeftShoulder => Some(gba_keypad::Keys::ButtonL),
+        Button::RightShoulder => Some(gba_keypad::Keys::ButtonR),
+        _ => None,
+    }
+}
+
 pub fn create_input() -> Sdl2Input {
     Sdl2Input {
         keyinput: gba_keypad::KEYINPUT_ALL_RELEASED,

platform/rustboyadvance-sdl2/src/main.rs

@@ -16,7 +16,7 @@ use std::cell::RefCell;
 use std::rc::Rc;
 
 use std::fs;
-use std::io::Read;
+use std::io::{Cursor, Read};
 use std::path::{Path, PathBuf};
 use std::process;
 use std::time;
@@ -192,6 +192,26 @@ 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");
+    controller_subsystem.load_mappings_from_read(&mut Cursor::new(controller_mappings))?;
+
+    let available_controllers = (0..controller_subsystem.num_joysticks()?)
+        .filter(|&id| controller_subsystem.is_game_controller(id))
+        .collect::<Vec<u32>>();
+
+    let _active_controller = match available_controllers.first() {
+        Some(&id) => {
+            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") {
         Some(path) => path.to_string(),
         _ => {
@@ -298,6 +318,12 @@ fn main() -> Result<(), Box<dyn std::error::Error>> {
                     Scancode::Space => frame_limiter = true,
                     k => input.borrow_mut().on_keyboard_key_up(k),
                 },
+                Event::ControllerButtonDown { button, .. } => {
+                    input.borrow_mut().on_controller_button_down(button);
+                },
+                Event::ControllerButtonUp { button, .. } => {
+                    input.borrow_mut().on_controller_button_up(button);
+                },
                 Event::Quit { .. } => break 'running,
                 Event::DropFile { filename, .. } => {
                     // load the new rom