Arduino sketch to Zoom in/out view and increase/decrease brush size in Krita, using a Digispark ATtiny85 board

digispark_rotary-encoder-Krita.ino

/* 
 * Kritary - Krita Rotary Zoom and Brush Size Controller
 * [Using a Digispark (ATtiny85) and a rotary encoder]
 * 
 * Copyright (C) 2020 Samuele RINI <samuele.rini76 [AT] gmail.com>
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 * 
 * 
 * 
 * 
 * ######################################################################################
 * Realized adapting and modifing the two amazing pieces 
 * of code, [1] and [2], as noted below:
 * ######################################################################################
 * 
 * 
 * 
 * 
 * #####
 * # 1 # --------------------------------------------------------------------------------
 * #####
 * 
 * ===== T H E   K N O B =====
 *   Media Controller Mk III
 * ----- By Frank Lumien -----
 *        www.lumien.se
 * ===========================
 *       Arduino code by:
 *  IAmOrion aka James Tanner
 * ===========================
 * 
 * Version 2.0
 *                                                     Changes in this fork
 * FUNCTIONS                                           --------------------
 * Turn knob left: Volume down                         "-" to zoom out
 * Turn knob right: Volume up                          "+" to zoom in
 * Press knob: Play & Pause (alternating)              zoom reset
 * Press and turn knob left: Previous track            decrease brush size
 * Press and turn knob right: Next track               increase brush size
 * 
 * Note: You can change all of these functions, see Settings.h for more.
 *
 * PINOUT, Digispark to KY-040
 * P0   to  CLK
 * P2   to  DT
 * P5   to  SW  // RESET disabled
 * VIN  to  GND // reversed
 * GND  to  +5V // reversed
 * Note: The position of these pins may depend on your board and encoder.
 * If you have already soldered or if The Knob doesn’t behave as expected,
 * you can adjust the pin settings in Settings.h
 * 
 * CONNECTING
 * See https://digistump.com/wiki/digispark/tutorials/connecting for how
 * to connect, get drivers and add set up Arduino for the Digispark bord.
 * 
 * Set board to "Digispark (Default - 16.5Mhz)"
 * 
 * COMPILING
 * Get the Trinket library from https://github.com/adafruit/Adafruit-Trinket-USB/tree/master/TrinketHidCombo
 * When compiling you will likely get warning messages related to the Trinket 
 * library. This is normal and does not mean that something is wrong. As long 
 * as the compilation finishes, you are good to go.
 * 
 * #####
 * # 2 # --------------------------------------------------------------------------------
 * #####
 *
 * TinyMultimediaController - Multimedia controller using a Digispark
 *                            (ATtiny85) and a rotary encoder
 * 
 * Copyright (C) 2018 Costin STROIE <costinstroie@eridu.eu.org>
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

#include "DigiKeyboard.h"

//Pin settings
#define encoderPinA 2 // DT -- (volume DOWN)
#define encoderPinB 0 // CLK - (volume UP)
#define encoderButton 5
#define ROTARY_LED 1

// LED stuff
bool          ledLight    = false;  // Status flag for the LED (on or off)
unsigned long ledTimeout  = 0UL;    // The time when the LED will turn off
unsigned long ledDelay    = 30UL;   // Time delay after which the LED turns off

// Function settings. To change any of the functions, replace
// the MMKEY_* commands with any of the examples below.

// all actions will be done with the 
// LEFT CONTROL modifier, in the sketch
#define LEFT_ACTION 0x38 // "-"
#define LEFT_ACTION_MODE1 KEY_8

#define RIGHT_ACTION 0x30 // "+"
#define RIGHT_ACTION_MODE1 KEY_9

#define BUTTON_ACTION_SINGLE KEY_0

#define TRINKET
#include <avr/power.h>

#define LATCHSTATE 3
int buttonState = LOW, lastButtonState = LOW;
long lastDebounceTime = 0, debounceDelay = 50;
int _position = 0, _positionExt = 0;
int8_t _oldState; bool btnPressed=false, btnReleased=false, pressedRotary=false;

byte bitLed = _BV(ROTARY_LED);

const int8_t encoderStates[] = {
  0, -1, 1, 0,
  1, 0, 0, -1,
  -1, 0, 0, 1,
  0, 1, -1, 0
};

void setup() {
  if (F_CPU == 16000000) clock_prescale_set(clock_div_1);
  
  pinMode(encoderPinA, INPUT);
  pinMode(encoderPinB, INPUT);
  pinMode(encoderButton, INPUT);
  digitalWrite(encoderPinA, HIGH);
  digitalWrite(encoderPinA, HIGH);
  digitalWrite(encoderButton, LOW);
  _oldState = 3;

  // Set the LED pin to output and flash it longer
  pinMode(ROTARY_LED,    OUTPUT);
  ledOn();
  ledTimeout += ledDelay;

  // this is generally not necessary but with some older systems it seems to
  // prevent missing the first character after a delay:
  DigiKeyboard.sendKeyStroke(0);
  DigiKeyboard.delay(250);
}

/**
  Send a media keypress

  @param key the key code to send
*/
void keySend(byte key/* , byte mod */) {
  // Turn the LED on
  ledOn();
  // Send the key
  DigiKeyboard.sendKeyStroke(key, MOD_CONTROL_LEFT);
}

/*
  Turn the LED on and set the timeout
*/
void ledOn() {
  if (!ledLight) {
    ledLight = true;
    PORTB |= bitLed;
  }
  ledTimeout = millis() + ledDelay;
}

/*
  Check the timeout and turn the LED off

  @param nowMillis cached millis()
*/
void ledOff(unsigned long nowMillis) {
  if (ledLight and (nowMillis > ledTimeout)) {
    ledLight = false;
    PORTB &= ~bitLed;
  }
}

void loop() {
  // Keep the time
  unsigned long nowMillis = millis();

  static int pos = 0;
  tick();
  int newPos = getPosition();
  if (pos != newPos) {
    if (newPos < pos) {
      if (!btnPressed) {
        keySend(LEFT_ACTION);
      } else {
        pressedRotary=true;
        keySend(LEFT_ACTION_MODE1);
      }
    }
    else if (newPos > pos){
     if (!btnPressed) {
        keySend(RIGHT_ACTION);
      } else {
        pressedRotary=true;
        keySend(RIGHT_ACTION_MODE1);
      }
    }
    pos = newPos;
  }
  int reading = digitalRead(encoderButton);
  if (reading != lastButtonState) {
    lastDebounceTime = millis();
  }
  if ((millis() - lastDebounceTime) > debounceDelay) {
    if (reading != buttonState) {
      buttonState = reading;
      if (buttonState == HIGH) {
        btnPressed=true;
      } else if (buttonState == LOW){
        btnReleased=true;
      }
    } 
  }
  lastButtonState = reading;

  if (btnPressed == true && btnReleased ==true && pressedRotary ==false) {
    keySend(BUTTON_ACTION_SINGLE);
    btnPressed=false;btnReleased=false;
  } else if (btnPressed == true && btnReleased == true && pressedRotary == true) {
    //RELEASED_AFTER_HELD_ROTATION
    btnPressed=false;btnReleased=false;pressedRotary=false;
  }

  // Turn the LED off, if timed out
  ledOff(nowMillis);
}

int  getPosition() {
  return _positionExt;
}

void setPosition(int newPosition) {
  _position = ((newPosition<<2) | (_position & 0x03));
  _positionExt = newPosition;
}

void tick(void) {
  int sig1 = digitalRead(encoderPinA);
  int sig2 = digitalRead(encoderPinB);
  int8_t thisState = sig1 | (sig2 << 1);
  if (_oldState != thisState) {
    _position += encoderStates[thisState | (_oldState<<2)];
    if (thisState == LATCHSTATE)
      _positionExt = _position >> 2;
    _oldState = thisState;
  }
}