function (evt) {
    if (evt.touches.length !== 1 || !this.data.touchEnabled) { return; }
    this.touchStart = {
      x: evt.touches[0].pageX,
      y: evt.touches[0].pageY
    };
    this.touchStarted = true;
  }
function (evt) {
    if (evt.touches.length !== 1 || !this.data.touchEnabled) { return; }
    this.touchStart = {
      x: evt.touches[0].pageX,
      y: evt.touches[0].pageY
    };
    this.touchStarted = true;
  }
function ( evt ) { if ( evt . touches . length !== 1 || ! this . data . touchEnabled ) { return ; } this . touchStart = { x : evt . touches [ 0 ] . pageX , y : evt . touches [ 0 ] . pageY } ; this . touchStarted = true ; }
Register touch down to detect touch drag.
Register touch down to detect touch drag .
touchstart event handler