Processing keyboard input

Keyboard.pde

import java.awt.event.KeyListener;
import java.awt.event.FocusListener;
import java.awt.event.KeyEvent;
import java.awt.event.FocusEvent;
import static java.awt.event.KeyEvent.*;

/*
 * Keyboard input handler for processing
 * Coded with care by Daniel Boerlage 2015
 *
 * example usage:
 * if(keyboard.upArrowPressed()) {
 *   moveUp();
 * }
 * if(keyboard.onCharDown(' ')) {
 *   fireBullet();
 * }
 */
class Keyboard implements KeyListener, FocusListener {

  /*
   * ArrayList of keyCodes to keep track of the current keys pressed
   * keyCodes are just integers that java uses to keep track of keys on your keyboard
   * We use Integer instead of int because you cant have an ArrayList of the primitive type int
   * warning: most modern usb keyboards have a small key rollover
   * For example keyboards with three-key rollover can reliably detect only any three keys used simultaneously
   * So isDown may return false even when the key is actually being pressed if many other keys are also being pressed
   */
  ArrayList<Integer> keysDown;

  // Constructor: tells the sketch to send the keyboard class all key events like keyPressed() and focus events like focusGained()
  Keyboard(PApplet parent) {
    parent.addKeyListener(this);
    parent.addFocusListener(this);
    keysDown = new ArrayList<Integer>();
  }

  // General method to detect if a particular keyCode is down
  boolean isKeyCodeDown(Integer code) {
    return keysDown.contains(code);
  }

  /*
   * Similar to isKeyCodeDown, but uses the key and then immediatley disposes it,
   * This method is useful for example when shooting a single bullet;
   * you dont want to shoot bullets every frame that the trigger key is held down in
   * the arrayList remove function returns true if the original list contained the parameter
   */
  boolean onKeyCodeDown(Integer code) {
    return keysDown.remove(code);
  }

  /*
   * returns true if the key corresponding to the character c is currently pressed down
   * character literals must be wrapped in single quotes, for example 'a' or ' ' or even '\t' for tab
   */
  boolean isCharDown(char c) {
    return isKeyCodeDown(charToKeyCode(c));
  }

  // one-off version of isCharDown
  boolean onCharDown(char c) {
    return onKeyCodeDown(charToKeyCode(c));
  }

  /**
   * create as many single key methods as necessary for keys that cant be represented by characters
   * a few examples are below
   * reference http://docs.oracle.com/javase/7/docs/api/java/awt/event/KeyEvent.html for KeyCode constants
   */
  boolean upArrowPressed() {
    return isKeyCodeDown(VK_UP);
  }

  boolean downArrowPressed() {
    return isKeyCodeDown(VK_DOWN);
  }

  boolean leftArrowPressed() {
    return isKeyCodeDown(VK_LEFT);
  }

  boolean rightArrowPressed() {
    return isKeyCodeDown(VK_RIGHT);
  }

  boolean shiftPressed() {
    return isKeyCodeDown(VK_SHIFT);
  }

  boolean controlPressed() {
    return isKeyCodeDown(VK_CONTROL);
  }

  // ...

  /*
   * KeyListener method that adds a keyCode to keysDown
   * When a key is held down, the os sends multiple key pressed events like holding backspace to delete multiple words in a text editor
   * Our program recieves these repeated events and shouldnt add them to the keysDown list because they would clutter the list with duplicate keyCodes
   */
  void keyPressed(KeyEvent ev) {
    if (!isKeyCodeDown(ev.getKeyCode()))
      keysDown.add(ev.getKeyCode());
  }

  /*
   * KeyListener method that removes a keyCode from keysDown
   * we cast to int with the code (Integer) because if we dont the arraylist remove thinks we are using the integer as an index instead of an element
   */
  void keyReleased(KeyEvent ev) {
    keysDown.remove((Integer)ev.getKeyCode());
  }

  // KeyListener method - no use
  void keyTyped(KeyEvent ev) { }

  // FocusListener method - no use
  void focusGained(FocusEvent ev) { }

  // FocusListener method - without this defocusing and refocusing the sketch window breaks everything
  void focusLost(FocusEvent ev) {
    keysDown.clear();
  }

  // utility method to convert characters to their integer keyCode equivalent
  Integer charToKeyCode(char c) {
    return new Integer(Character.toUpperCase(c));
  }
}

// the main instance of keyboard - consider renaming to something shorter like 'kbd'
Keyboard keyboard = new Keyboard(this);

Keyboard_core.pde

import java.awt.event.KeyAdapter;
import java.awt.event.KeyEvent;
import static java.awt.event.KeyEvent.*;
 
/*
 * Keyboard input handler for processing (core version)
 * Coded with care by Daniel Boerlage 2015
 *
 * example usage:
 * if(keyboard.upArrowPressed()) {
 *   moveUp();
 * }
 */
class Keyboard extends KeyAdapter {
 
  /*
   * ArrayList of keyCodes to keep track of the current keys pressed
   * keyCodes are just integers that java uses to keep track of keys on your keyboard
   * We use Integer instead of int because you cant have an ArrayList of the primitive type int
   * warning: most modern usb keyboards have a small key rollover
   * For example keyboards with three-key rollover can reliably detect only any three keys used simultaneously
   * So isDown may return false even when the key is actually being pressed if many other keys are also being pressed
   */
  ArrayList<Integer> keysDown;

  Keyboard(PApplet parent) {
    parent.addKeyListener(this);
    keysDown = new ArrayList<Integer>();
  }
 
  /*
   * create as many single key methods as necessary
   * a few examples are below
   * reference http://docs.oracle.com/javase/7/docs/api/java/awt/event/KeyEvent.html for KeyCode constants
   */
  boolean aPressed() {
    return keysDown.contains(VK_A);
  }
  
  boolean upArrowPressed() {
    return keysDown.contains(VK_UP);
  }
 
  boolean shiftPressed() {
    return keysDown.contains(VK_SHIFT);
  }
 
  void keyPressed(KeyEvent ev) {
    if (!isKeyCodeDown(ev.getKeyCode()))
      keysDown.add(ev.getKeyCode());
  }
 
  void keyReleased(KeyEvent ev) {
    keysDown.remove((Integer)ev.getKeyCode());
  }
}
 
// the main instance of keyboard - consider renaming to something shorter like 'kbd'
Keyboard keyboard = new Keyboard(this);

Keyboard_undoc.pde

import java.awt.event.KeyListener;
import java.awt.event.FocusListener;
import java.awt.event.KeyEvent;
import java.awt.event.FocusEvent;
import static java.awt.event.KeyEvent.*;

/*
 * Keyboard input handler for processing
 * Coded with care by Daniel Boerlage 2015
 */
class Keyboard implements KeyListener, FocusListener {

  ArrayList<Integer> keysDown;

  Keyboard(PApplet parent) {
    parent.addKeyListener(this);
    parent.addFocusListener(this);
    keysDown = new ArrayList<Integer>();
  }

  boolean isKeyCodeDown(Integer code) {
    return keysDown.contains(code);
  }

  boolean onKeyCodeDown(Integer code) {
    return keysDown.remove(code);
  }

  boolean isCharDown(char c) {
    return isKeyCodeDown(charToKeyCode(c));
  }
  
  boolean onCharDown(char c) {
    return onKeyCodeDown(charToKeyCode(c));
  }
  
  boolean upArrowPressed() {
    return isKeyCodeDown(VK_UP);
  }

  boolean downArrowPressed() {
    return isKeyCodeDown(VK_DOWN);
  }

  boolean leftArrowPressed() {
    return isKeyCodeDown(VK_LEFT);
  }

  boolean rightArrowPressed() {
    return isKeyCodeDown(VK_RIGHT);
  }

  boolean shiftPressed() {
    return isKeyCodeDown(VK_SHIFT);
  }

  boolean controlPressed() {
    return isKeyCodeDown(VK_CONTROL);
  }
  
  void keyPressed(KeyEvent ev) {
    if (!isKeyCodeDown(ev.getKeyCode()))
      keysDown.add(ev.getKeyCode());
  }

  void keyReleased(KeyEvent ev) {
    keysDown.remove((Integer)ev.getKeyCode());
  }

  void keyTyped(KeyEvent ev) { }

  void focusGained(FocusEvent ev) { }

  void focusLost(FocusEvent ev) {
    keysDown.clear();
  }

  Integer charToKeyCode(char c) {
    return new Integer(Character.toUpperCase(c));
  }
}

Keyboard keyboard = new Keyboard(this);