tappable.js

MiniApp.Tappable = {

  _tap_tapCount: null,
  _tap_candidateTouch: null,
  _tap_eventTimer: null,

  tapWiggle: 10,
  tapDelay: 200,

  tapStart: function(evt){
    var viewTouches = evt.touchesForView(this),
        shouldCancel = NO;

    // We don't want events triggering during a touch, will be reset when touch is over if it's a candidate
    if (this._tap_eventTimer) this._tap_eventTimer.invalidate();

    // We have an activeTap but another touch has been started
    if (this._tap_tapCount && viewTouches) shouldCancel = YES;

    if (shouldCancel) {
      this._tap_cancelTap();
      return;
    }

    // This touch is a candidate
    this._tap_candidateTouch = {
      startTime: Date.now(),
      identifier: evt.identifier
    }

  },

  tapsChanged: function(evt, viewTouches){
    var touch = viewTouches[0];

    // Somehow another touch got in
    var tooManyTouches = (
      viewTouches.length > 1 ||
      !this._tap_candidateTouch ||
      touch.identifier !== this._tap_candidateTouch.identifier
    );

    // Touch moved too much
    var touchMoved = touch.dragDistance() > this.get('tapWiggle');

    if (tooManyTouches || touchMoved) this._tap_cancelTap();
  },

  tapEnd: function(evt){
    if (this._tap_candidateTouch) {
      if (evt.dragDistance() > this.get('tapWiggle') || Date.now() - this._tap_candidateTouch.startTime > this.get('tapDelay') ) {
        // Touch moved too much or took too long
        this._tap_cancelTap();
      } else {
        this._tap_addTap();
      }
    }
  },

  _tap_addTap: function(){
    if (this._tap_eventTimer) this._tap_eventTimer.invalidate();

    this._tap_tapCount = (this._tap_tapCount || 0) + 1;
    this._tap_candidateTouch = null;
    this._tap_eventTimer = SC.Timer.schedule({
      target: this,
      action: '_tap_triggerTap',
      interval: this.get('tapDelay')
    });
  },

  _tap_cancelTap: function(){
    if (this._tap_eventTimer) this._tap_eventTimer.invalidate();
    this._tap_tapCount = null;
    this._tap_candidateTouch = null;
    this._tap_eventTimer = null;
  },

  _tap_triggerTap: function(){
    this.tap(this._tap_tapCount);

    this._tap_tapCount = null;
    this._tap_candidateTouch = null;
    this._tap_eventTimer = null;
  }

};