Refactor code substantially, moving buttons into separate classes and using a lot more pointers to conserve memory until it is needed.

Button.h

@@ -0,0 +1,97 @@
+#ifndef _BUTTON_H_
+#define _BUTTON_H_
+
+#include <Encoder.h>
+#include <Mux.h>
+#include <Bounce2.h>
+
+using namespace admux;
+
+class Joystick; // forward declaration
+
+enum ButtonType {
+  BUTTON_PASSTHRU = 0x1, // always use the (debounced) absolute state of the input
+  BUTTON_PULSED = 0x2, // on button press, send an on signal followed immediately by an off signal.
+  BUTTON_PULSED_DOUBLE_ACTION = 0x4, // Send a button press twice - once for press and once for release.
+  BUTTON_PULSED_DOUBLE_ACTION_SPLIT = 0x8, // Send two separate button presses - one button on press, another on release.
+  BUTTON_LATCHED_MOMENTARY = 0x10,
+  ENCODER_PULSED_SPLIT = 0x20 // A rotary encoder that should be treated as two different pulsed/momentary buttons, one for each direction
+};
+
+// The abstract button base class. A button must have, at a minimum:
+// * a button *type* (typically automatically assigned by the constructor)
+// * at least one "virtual button" - that is, a Joystick input that it controls
+// * an update method.
+class Button {
+ public:
+  Button(uint8_t vbutton);
+  virtual void Update(Joystick* js) = 0;
+  virtual void ReleaseButtons(Joystick* js);
+  ButtonType type;
+
+ protected:
+  uint8_t vbutton;
+};
+
+// An abstract class for a momentary/pushbutton or toggle switch. Special properties:
+// * needs to be explicitly debounced
+// * may use the microcontroller's built-in pullup resistor mode to eliminate noise
+// * may be attached to a multiplexer. In this case, the `pin` value will be treated as a multiplexer channel,
+//   and the multiplexer logic will be automatically invoked by Update()
+class SwitchButton : public Button {
+ public:
+  SwitchButton(uint8_t pin, uint8_t vbutton, bool pullup, Mux* mux);
+  virtual void Update(Joystick* js) = 0;
+  bool BouncerUpdate(); // returns true if the pin's status has changed
+  bool On();
+
+ protected:
+  Bounce bouncer;
+  bool inverted;
+  Mux *mux;
+  uint8_t channel_id;
+};
+
+class PassthruButton : public SwitchButton {
+ public:
+  PassthruButton(uint8_t pin, uint8_t vbutton, bool pullup = true, Mux* mux = NULL);
+  void Update(Joystick* js);
+};
+
+class LatchedButton : public SwitchButton {
+ public:
+  LatchedButton(uint8_t pin, uint8_t vbutton, bool pullup = true, Mux* mux = NULL);
+  void Update(Joystick* js);
+
+ protected:
+  bool pressed;
+};
+
+class PulsedButton : public SwitchButton {
+ public:
+  PulsedButton(uint8_t pin, uint8_t vbutton, bool double_action = false, bool split = false, bool pullup = true, Mux* mux = NULL);
+  void Update(Joystick* js);
+  void ReleaseButtons(Joystick* js);
+
+ protected:
+  bool double_action;
+  bool split;
+  uint8_t vbutton2;
+};
+
+class EncoderButton : public Button {
+ public:
+  EncoderButton(uint8_t pin1, uint8_t pin2, uint8_t vbutton);
+  void Update(Joystick* js);
+  void ReleaseButtons(Joystick* js);
+
+ protected:
+  Encoder* encoder;
+  long last_value;
+  uint8_t vbutton2;
+};
+
+// Internal use only.
+#define _BUTTON_PULSED_TYPES (BUTTON_PULSED | BUTTON_PULSED_DOUBLE_ACTION | BUTTON_PULSED_DOUBLE_ACTION_SPLIT | ENCODER_PULSED_SPLIT)
+
+#endif