famo.us - Sleep after n milliseconds of no touch/mouse movement

famous-sleepOnIdle.js

var Engine = require('famous/core/Engine');

/**
 * Sleep after n milliseconds of no touch/mouse movement
 */
function sleepOnIdle(idleMS) {
  var lastMoveMS = Date.now();

  window.addEventListener('mousemove', _handleMovement, true);
  window.addEventListener('touchmove', _handleMovement, true);
  Engine.on('prerender', _checkSleep);

  function _handleMovement() {
    lastMoveMS = Date.now();
    Engine.setFPSCap(60);
  }

  function _checkSleep() {
    if (Date.now() - lastMoveMS > idleMS && lastMoveMS !== -1) {
      Engine.setFPSCap(1);
      lastMoveMS = -1;
    }
  }
}