SDL Gamepad Input Stuff

main.cpp

#include <cstdio>
#include <string>
#include <vector>
#include <SDL.h>

void logJoystickEvent(SDL_Event e);
std::string showHatState(Uint8 hat);

int main(int argc, char* argv[]) {
	// Detect first gamepad on which a key is pressed, then log its events.

	bool quit = false;
	bool deviceFound = false;
	SDL_Event e;
	int num_joysticks = 0;
	SDL_Joystick* activeJoystick = nullptr;
	SDL_JoystickID activeJoystickID;
	auto joysticks = std::vector<SDL_Joystick*>();

	if (SDL_Init(SDL_INIT_JOYSTICK) < 0) {
		printf("SDL initialization failed.  Error: %s\n", SDL_GetError());
	}

	num_joysticks = SDL_NumJoysticks();
	for (int i = 0; i < num_joysticks; i++) {
		auto joystick = SDL_JoystickOpen(i);
		if (joystick == nullptr) {
			printf("Warning: unable to open game controller %d!  SDL Error: %s\n", i, SDL_GetError());
		}
		else {
			joysticks.push_back(joystick);
		}
	}

	while (!deviceFound && !quit) {
		while (SDL_PollEvent(&e) != 0) {
			if (e.type == SDL_QUIT) {
				quit = true;
			}
			else if (e.type == SDL_JOYDEVICEADDED) {
				auto joystick = SDL_JoystickOpen(e.jdevice.which);
				if (joystick == nullptr) {
					printf("Warning: unable to open game controller %d!  SDL Error: %s\n", e.jdevice.which, SDL_GetError());
				}
				else {
					joysticks.push_back(joystick);
				}
			}
			else if (e.type == SDL_JOYDEVICEREMOVED) {
				auto joystick = SDL_JoystickFromInstanceID(e.jdevice.which);
				SDL_JoystickClose(joystick);
			}
			else if (e.type == SDL_JOYBUTTONDOWN) {
				activeJoystick = SDL_JoystickFromInstanceID(e.jbutton.which);
				deviceFound = true;
				logJoystickEvent(e);
			}
		}
	}

	// Stop listening to all other joysticks;
	activeJoystickID = SDL_JoystickInstanceID(activeJoystick);
	auto it = joysticks.begin();
	while (it != joysticks.end()) {
		if (SDL_JoystickInstanceID(*it) != activeJoystickID) {
			it = joysticks.erase(it);
		}
		else {
			it++;
		}
	}

	while (!quit) {
		while (SDL_PollEvent(&e) != 0) {
			if (e.type == SDL_QUIT) {
				quit = true;
			}
			else if (e.type == SDL_JOYBUTTONUP) {
				logJoystickEvent(e);
				if (e.jbutton.button == 7) { // start on xbox 360 controller
					quit = true;
				}
			}
			else if (e.type == SDL_JOYBUTTONDOWN
				  || e.type == SDL_JOYAXISMOTION
				  || e.type == SDL_JOYHATMOTION) {
				logJoystickEvent(e);
			}
			else if (e.type == SDL_JOYDEVICEREMOVED) {
				if (e.jdevice.which == activeJoystickID) {
					printf("Error: active joystick removed.\n");
					quit = true;
				}
			}
		}
	}

	SDL_JoystickClose(activeJoystick);
	SDL_Quit();
	return 0;
}

void logJoystickEvent(SDL_Event e) {
	Uint32 timestamp = 0;
	std::string eventType;
	int index;
	std::string otherData;

	switch (e.type) {
	case SDL_JOYBUTTONUP:
		timestamp = e.jbutton.timestamp;
		eventType = "RELEASE";
		index = e.jbutton.button;
		otherData = "";
		break;
	case SDL_JOYBUTTONDOWN:
		timestamp = e.jbutton.timestamp;
		eventType = "PRESS";
		index = e.jbutton.button;
		otherData = "";
		break;
	case SDL_JOYHATMOTION:
		timestamp = e.jhat.timestamp;
		eventType = "POV";
		index = e.jhat.hat;
		otherData = showHatState(e.jhat.value);
		break;
	case SDL_JOYAXISMOTION:
		timestamp = e.jaxis.timestamp;
		eventType = "STICK";
		index = e.jaxis.axis;
		otherData = std::to_string(e.jaxis.value);
		break;
	}

	printf("%u\t%s\t%u\t%s\n", timestamp, eventType.c_str(), index, otherData.c_str());
}

std::string showHatState(Uint8 hat) {
	switch (hat) {
	case SDL_HAT_LEFTUP:
		return "LU";
		break;
	case SDL_HAT_UP:
		return "XU";
		break;
	case SDL_HAT_RIGHTUP:
		return "RU";
		break;
	case SDL_HAT_LEFT:
		return "LX";
		break;
	case SDL_HAT_CENTERED:
		return "XX";
		break;
	case SDL_HAT_RIGHT:
		return "RX";
		break;
	case SDL_HAT_LEFTDOWN:
		return "LD";
		break;
	case SDL_HAT_DOWN:
		return "XD";
		break;
	case SDL_HAT_RIGHTDOWN:
		return "RD";
		break;
	default:
		return "??";
		break;
	}
}