Feature request: be able to set your own _getState() callback function

[grayconstruct]

I wanted the debounce and longpress capability that I enjoy from Button2 library but my input was a samd21 touch sensor. Might also have other inputs such as analog threshold or buttons on i2c IO expander. If we could set a custom _getState() handler and get around the check for valid pin in Button2::loop() then buttons that are not on digitalRead would be possible and a more generic way than the esp touch button implementation. I was able to do it by changing _getState() to virtual and derived class as follows, but it was extra work and I don't like changing libraries and having a bunch of notes about that in my code. Here's what I got that might give you ideas on a better way:

#pragma once
#ifndef Button2cb_h
#define Button2cb_h
#if defined(ARDUINO_ARCH_ESP32) || defined(ESP8266)
#include
#endif
#include "Arduino.h"
#include <Button2.h>
#define VIRTUAL_PIN 254
typedef byte (*ButtonStateCallbackFunction)(void);
class Button2cb : public Button2 {
protected:
ButtonStateCallbackFunction getState_cb = NULL;
public:
void begin(boolean activeLow = true);
boolean isPressedRaw() const;
void setGetStateHandler(ButtonStateCallbackFunction f);
private:
// note, to properly override this in the base class, it has to be made virtual in Button2.h
byte _getState();
};

/////////////////////////////////////////////////////////////////
/*
Button2cb.cpp
/
/////////////////////////////////////////////////////////////////
#include "Button2cb.h"
void Button2cb::begin(boolean activeLow / = true */)
{
pin = VIRTUAL_PIN; // this gets us past loop()'s (pin != UNDEFINED_PIN) check
longclick_detected_retriggerable = false;
_pressedState = activeLow ? LOW : HIGH;
setDebounceTime(DEBOUNCE_MS);
setLongClickTime(LONGCLICK_MS);
setDoubleClickTime(DOUBLECLICK_MS);
// this constructor allows us to get around setting pinMode on our VIRTUAL_PIN
state = _getState();
prev_state = state;
}
void Button2cb::setGetStateHandler(ButtonStateCallbackFunction f) {
getState_cb = f;
}
boolean Button2cb::isPressedRaw() const { // another digitalRead to work around
if(getState_cb != NULL)
return (getState_cb() == _pressedState);
return false;
}
/////////////////////////////////////////////////////////////////
// note, to properly override this in the base class, it has to be made virtual in Button2.h
byte Button2cb::_getState() {
if(getState_cb != NULL)
{
return getState_cb(); // use our installed callback function to get the virtual pin's state
}
return 0;
}

/////////////////// Now with the new class, I can use the following

Button2cb DebouncerQtColorChange;
// callback function to read our samd21 qTouch via the measure() function to get the analog value of the touch peripheral
byte ButtonQtColorGetState()
{
return (ButtonQtColorChange.measure() > QtThreshold) ? LOW : HIGH;
}

void setup()
{
DebouncerQtColorChange.begin(); // Button2 subclass
DebouncerQtColorChange.setGetStateHandler(ButtonQtColorGetState); // set my custom way to _getState()
DebouncerQtColorChange.setClickHandler(AnimationColorShiftButtonHandler);
DebouncerQtColorChange.setLongClickHandler(AnimationColorShiftButtonHandler);
}

[LennartHennigs]

Hey,
thank you for the suggestion.
Yes, I understand your request and problem. And that's a nice idea.
Give me some time to think about it how to best implement and handle this inside the lib.

Cheers
l.

[LennartHennigs]

Hey,
thought about your suggestion a bit.
I think some people might be not too familiar with inheritance when they are into Arduino programming.
Thus I'd like to introduce something like this:

• a function that allows you to set a custom getState() function, this eliminates the need for inheritance
• refactored up the code, to there is only digitalRead() used in _getState()
• kept the VIRTUAL_PIN to skip the pin setup in my begin() function
• In the example below I use a regular button pin but I think it makes the idea clear
• the only thing that is now not encapsulated is the initialization of the "custom button", here the pinMode(39, INPUT_PULLUP); but I feel that is ok

@grayconstruct Thoughts?

#include "Button2.h"

Button2 button;

byte myStateHandler() {
  return digitalRead(39);
}

void setup() {
  Serial.begin(9600);
  delay(100);
  Serial.println("\n\nTest");  
  button.begin(VIRTUAL_PIN);

  pinMode(39, INPUT_PULLUP);

  button.setGetStateFunction(myStateHandler);
  button.setTapHandler([](Button2 &b) {
    Serial.print("tap");
  });
}

void loop() {
  button.loop();
}