swipe detection example for Titanium

swipe_detection_example.js

var movementHistory = {
  pointAndTimeHistory: [],
  set: function(point) {
    // add this point into the point and time history for velocity calculations based on time & distance
    this.pointAndTimeHistory.push({
      time: new Date().getTime(),
      x: point.x,
      y: point.y
    });

    // trim history older than 300ms ago
    while ( (this.pointAndTimeHistory.length > 0) && ( (this.pointAndTimeHistory[0].time+300) < (new Date()).getTime() ) ) {
      this.pointAndTimeHistory.shift();
    }

    // get average horizonal velocity based on oldest co-ordinate and newest co-ordinate
    if (this.pointAndTimeHistory.length) {
      this.xVelocity = (point.x - this.pointAndTimeHistory[0].x) / (new Date() - this.pointAndTimeHistory[0].time);
      if (isNaN(this.xVelocity)) { this.xVelocity = 0; } // protect against NaN
      this.yVelocity = (point.y - this.pointAndTimeHistory[0].y) / (new Date() - this.pointAndTimeHistory[0].time);
      if (isNaN(this.yVelocity)) { this.yVelocity = 0; } // protect against NaN
    } else {
      this.xVelocity = 0;
      this.yVelocity = 0;
    }

    // store the current position
    this.x = point.x;
    this.y = point.y;
  }
};

view.addEventListener('touchstart', function(e) {
  movementHistory.set(e.globalPoint);
});

view.addEventListener('touchmove', function(e) {
  movementHistory.set(e.globalPoint);
  if (Math.abs(movementHistory.xVelocity) > Math.abs(movementHistory.yVelocity)) {
    if (Math.abs(movementHistory.xVelocity) > 1)  {
      // horizontal swipe as user has gestured quickly but not lifted their finger
      // if x > 0 then swipe is left to right
    }
  } else {
    if (Math.abs(movementHistory.yVelocity) > 1)  {
      // vertical swipe as user has gestured quickly but not lifted their finger
      // if y > 0 then vertically down
    }
  }
});

view.addEventListener('touchend', function(e) {
  movementHistory.set(e.globalPoint);
  if (Math.abs(movementHistory.xVelocity) > Math.abs(movementHistory.yVelocity)) {
    if (Math.abs(movementHistory.xVelocity) > 0.25)  {
      // horizontal swipe as user has gestured and lifted their finger
    }
  } else {
    if (Math.abs(movementHistory.yVelocity) > 0.25)  {
      // vertical swipe as user has gestured and lifted their finger
    }
  }
});