    /**
     * @private
     */
    Ext.define('Ext.fx.easing.Linear', {

        extend: 'Ext.fx.easing.Abstract',

        alias: 'easing.linear',

        config: {
            duration: 0,
            endValue: 0
        },

        updateStartValue: function(startValue) {
            this.distance = this.getEndValue() - startValue;
        },

        updateEndValue: function(endValue) {
            this.distance = endValue - this.getStartValue();
        },

        getValue: function() {
            var deltaTime = Ext.Date.now() - this.getStartTime(),
                duration = this.getDuration();

            if (deltaTime > duration) {
                this.isEnded = true;
                return this.getEndValue();
            }
            else {
                return this.getStartValue() + ((deltaTime / duration) * this.distance);
            }
        }
    });