Button.h

#ifndef BUTTON_LIBRARY_INCLUDED
#define BUTTON_LIBRARY_INCLUDED

#include <inttypes.h>

class Button;
typedef void (*buttonEventHandler)(const Button&);

struct ButtonCBHandlers {
    ButtonCBHandlers() : cb_onPress(0), cb_onRelease(0), cb_onClick(0), cb_onHold(0) {}
    buttonEventHandler  cb_onPress;
    buttonEventHandler  cb_onRelease;
    buttonEventHandler  cb_onClick;
    buttonEventHandler  cb_onHold;
};

/**
  * A simple button class that configures the Arduino, filters bounces, and
  * detects clicks and holds. Use `ButtoCB` if you would like to add callback handlers.
  */
class Button {
public:

    enum {
        PULL_DOWN       = 0,
        PULL_UP         = 1,
        INTERNAL_PULLUP = 2,

        DEFAULT_HOLD_TIME       = 500,
        DEFAULT_BOUNCE_DURATION = 20
    };

    /**
     *  Construct a button.
     *  'buttonPin' is the pin for this button to use.
     *  'resistor' is the wiring of the button.
     *      - A PULL_DOWN resistor means the button is tied to ground, and the button connects to HIGH on close.
     *      - A PULL_UP resistor is tied to Vcc, and the button connects to LOW on close.
     *      - An INTERNAL_PULLUP uses the internal resistor, and the button connects to LOW on close.
     *  'debounceDuration' is how long it takes the button to settle, mechanically, when pressed.
     */
    Button(uint8_t buttonPin=255, uint8_t resistor = PULL_DOWN, uint16_t debounceDuration = DEFAULT_BOUNCE_DURATION);

    void init(uint8_t buttonPin, uint8_t resistor = PULL_DOWN, uint16_t debounceDuration = DEFAULT_BOUNCE_DURATION);
    const int pin() const {
        return m_myPin;
    }

    /** Process the button state change. Should be called from loop().
     *  Will call the callbacks, if needed.
     */
    void process();

    /// true if pressed on this loop
    bool press() const;
    /// true if the the button is down
    bool isDown() const;
    /// true if the button is held to the trigger time
    bool held() const;
    /// return the time the button has been held down
    uint32_t holdTime() const;
    /// return the last time the button was pressed down
    uint32_t pressedTime() const {
        return m_pressedStartTime;
    }

    void setHoldThreshold(uint32_t holdTime);
    const uint16_t holdThreshold() const {
        return m_holdEventThreshold;
    }

    /** If false (the default) only one hold event is set.
      * If true the a hold event is sent every holdTime()
      */
    void setHoldRepeats(bool holdRepeats) { m_holdRepeats = holdRepeats; }

    /// Return true of the hold event repeats.
    const bool holdRepeats() const {
        return m_holdRepeats;
    }

    /** If a repeating hold, returns the number of holds
      * times. The first is '1'.
      */
    int nHolds() const {
        return m_nHolds;
    }

    int cycle(bool* on = 0) const {
        if (on) *on = false;            

        if (held()) {
            if (on) *on = (m_nHolds & 1) ? true : false;
            return (m_nHolds + 1) / 2;
        }
        return 0;
    }

    // For testing - do not call in normal use.
    const ButtonCBHandlers* queryHandlers() const {
        return m_handlers;
    }
    void enableTestMode(bool testMode);
    void testPress();
    void testRelease();

private:
    bool stateChanged() const;
    bool queryButtonDown() const;

    bool                m_holdRepeats;
    uint8_t             m_myPin;
    uint8_t             m_mode;
    uint8_t             m_state;
    uint16_t            m_nHolds;
    uint16_t            m_holdEventThreshold;
    uint16_t            m_debounceDuration;
    uint32_t            m_pressedStartTime;
    uint32_t            m_debounceStartTime;

protected:
    const ButtonCBHandlers* m_handlers;
};


/**
 * Creates a button that supports Callbacks for Press, Release, Click, and Hold.
 * Uses a bit more memory (24 bytes) so the functionality is opt-in.
 */
class ButtonCB : public Button {
public:
    ButtonCB(uint8_t buttonPin=255,  uint8_t resistor = PULL_DOWN, uint16_t debounceDuration = DEFAULT_BOUNCE_DURATION) :
        Button(buttonPin, resistor, debounceDuration)
    {
        m_handlers = &m_handlerData;
    }

    /** Every button press generates 'press' and 'release'.
      * It may also generate a 'click' or a 'hold'.
      */
    void setPressHandler(buttonEventHandler handler);
    void setReleaseHandler(buttonEventHandler handler);
    void setClickHandler(buttonEventHandler handler);
    void setHoldHandler(buttonEventHandler handler);

private:
    ButtonCBHandlers m_handlerData;
};

#endif // BUTTON_LIBRARY_INCLUDED