JoystickInput.h

#pragma once
 
#include <cstddef>
#include <cstdint>
#include <vector>
 
namespace Ship
{
namespace joystick
{
 
constexpr double kAxisMax = 32767.0;
 
constexpr int kSliderAxisOffset = 5;
 
enum HatBits : std::uint8_t
{
   kHatCentered = 0x00,
   kHatUp       = 0x01, 
   kHatRight    = 0x02, 
   kHatDown     = 0x04, 
   kHatLeft     = 0x08, 
};
 
enum class PovDirection
{
   Centered,
   North,
   South,
   East,
   West,
   NorthEast,
   NorthWest,
   SouthEast,
   SouthWest,
};
 
PovDirection HatToPov(std::uint8_t hat);
 
inline double ScaleAxis(std::int16_t raw) { return static_cast<double>(raw) / kAxisMax; }
 
struct JoystickState
{
   std::vector<std::int16_t> axes;
   std::vector<std::uint8_t> buttons;
   std::vector<std::uint8_t> hats;
 
   std::int16_t Axis(int i) const { return (i >= 0 && std::size_t(i) < axes.size()) ? axes[std::size_t(i)] : 0; }
   bool         Button(int i) const { return i >= 0 && std::size_t(i) < buttons.size() && buttons[std::size_t(i)] != 0; }
   std::uint8_t Hat(int i) const { return (i >= 0 && std::size_t(i) < hats.size()) ? hats[std::size_t(i)] : kHatCentered; }
 
   double ScaledAxis(int i) const { return ScaleAxis(Axis(i)); }
   double ScaledSlider(int k) const { return ScaleAxis(Axis(kSliderAxisOffset + k)); }
};
 
class JoystickListener
{
public:
   virtual ~JoystickListener() = default;
   virtual void ButtonPressed(int button, const JoystickState& state) { }
   virtual void ButtonReleased(int button, const JoystickState& state) { }
   virtual void AxisMoved(int axis, const JoystickState& state) { }
   virtual void HatMoved(int hat, const JoystickState& state) { }
};
 
void DispatchChanges(const JoystickState& previous, const JoystickState& current, JoystickListener& listener);
 
} // namespace joystick
} // namespace Ship