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[2048.git] / js / keyboard_input_manager.js
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function KeyboardInputManager() {
  this.events = {};
 
  this.listen();
}
 
KeyboardInputManager.prototype.on = function (event, callback) {
  if (!this.events[event]) {
    this.events[event] = [];
  }
  this.events[event].push(callback);
};
 
KeyboardInputManager.prototype.emit = function (event, data) {
  var callbacks = this.events[event];
  if (callbacks) {
    callbacks.forEach(function (callback) {
      callback(data);
    });
  }
};
 
KeyboardInputManager.prototype.listen = function () {
  var self = this;
 
  var map = {
    38: 0, // Up
    39: 1, // Right
    40: 2, // Down
    37: 3  // Left
  };
 
  document.addEventListener("keydown", function (event) {
    var modifiers = event.altKey && event.ctrlKey && event.metaKey &&
                    event.shiftKey;
    var mapped    = map[event.which];
 
    if (!modifiers && mapped !== undefined) {
      event.preventDefault();
      self.emit("move", mapped);
    }
  });
 
  var retry = document.getElementsByClassName("retry-button")[0];
  retry.addEventListener("click", function (event) {
    event.preventDefault();
    self.emit("restart");
  });
};
 
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