The source code

    /**
     * @class Ext.form.SliderField
     * @extends Ext.form.Field
     * Wraps a {@link Ext.slider.MultiSlider Slider} so it can be used as a form field.
     * @constructor
     * Creates a new SliderField
     * @param {Object} config Configuration options. Note that you can pass in any slider configuration options, as well as
     * as any field configuration options.
     * @xtype sliderfield
     */
    Ext.form.SliderField = Ext.extend(Ext.form.Field, {

        /**
         * @cfg {Boolean} useTips
         * True to use an Ext.slider.Tip to display tips for the value. Defaults to <tt>true</tt>.
         */
        useTips : true,

        /**
         * @cfg {Function} tipText
         * A function used to display custom text for the slider tip. Defaults to <tt>null</tt>, which will
         * use the default on the plugin.
         */
        tipText : null,

        // private override
        actionMode: 'wrap',

        /**
         * Initialize the component.
         * @private
         */
        initComponent : function() {
            var cfg = Ext.copyTo({
                id: this.id + '-slider'
            }, this.initialConfig, ['vertical', 'minValue', 'maxValue', 'decimalPrecision', 'keyIncrement', 'increment', 'clickToChange', 'animate']);

            // only can use it if it exists.
            if (this.useTips) {
                var plug = this.tipText ? {getText: this.tipText} : {};
                cfg.plugins = [new Ext.slider.Tip(plug)];
            }
            this.slider = new Ext.Slider(cfg);
            Ext.form.SliderField.superclass.initComponent.call(this);
        },

        /**
         * Set up the hidden field
         * @param {Object} ct The container to render to.
         * @param {Object} position The position in the container to render to.
         * @private
         */
        onRender : function(ct, position){
            this.autoCreate = {
                id: this.id,
                name: this.name,
                type: 'hidden',
                tag: 'input'
            };
            Ext.form.SliderField.superclass.onRender.call(this, ct, position);
            this.wrap = this.el.wrap({cls: 'x-form-field-wrap'});
            this.resizeEl = this.positionEl = this.wrap;
            this.slider.render(this.wrap);
        },

        /**
         * Ensure that the slider size is set automatically when the field resizes.
         * @param {Object} w The width
         * @param {Object} h The height
         * @param {Object} aw The adjusted width
         * @param {Object} ah The adjusted height
         * @private
         */
        onResize : function(w, h, aw, ah){
            Ext.form.SliderField.superclass.onResize.call(this, w, h, aw, ah);
            this.slider.setSize(w, h);
        },

        /**
         * Initialize any events for this class.
         * @private
         */
        initEvents : function(){
            Ext.form.SliderField.superclass.initEvents.call(this);
            this.slider.on('change', this.onChange, this);
        },

        /**
         * Utility method to set the value of the field when the slider changes.
         * @param {Object} slider The slider object.
         * @param {Object} v The new value.
         * @private
         */
        onChange : function(slider, v){
            this.setValue(v, undefined, true);
        },

        /**
         * Enable the slider when the field is enabled.
         * @private
         */
        onEnable : function(){
            Ext.form.SliderField.superclass.onEnable.call(this);
            this.slider.enable();
        },

        /**
         * Disable the slider when the field is disabled.
         * @private
         */
        onDisable : function(){
            Ext.form.SliderField.superclass.onDisable.call(this);
            this.slider.disable();
        },

        /**
         * Ensure the slider is destroyed when the field is destroyed.
         * @private
         */
        beforeDestroy : function(){
            Ext.destroy(this.slider);
            Ext.form.SliderField.superclass.beforeDestroy.call(this);
        },

        /**
         * If a side icon is shown, do alignment to the slider
         * @private
         */
        alignErrorIcon : function(){
            this.errorIcon.alignTo(this.slider.el, 'tl-tr', [2, 0]);
        },

        /**
         * Sets the minimum field value.
         * @param {Number} v The new minimum value.
         * @return {Ext.form.SliderField} this
         */
        setMinValue : function(v){
            this.slider.setMinValue(v);
            return this;
        },

        /**
         * Sets the maximum field value.
         * @param {Number} v The new maximum value.
         * @return {Ext.form.SliderField} this
         */
        setMaxValue : function(v){
            this.slider.setMaxValue(v);
            return this;
        },

        /**
         * Sets the value for this field.
         * @param {Number} v The new value.
         * @param {Boolean} animate (optional) Whether to animate the transition. If not specified, it will default to the animate config.
         * @return {Ext.form.SliderField} this
         */
        setValue : function(v, animate, /* private */ silent){
            // silent is used if the setValue method is invoked by the slider
            // which means we don't need to set the value on the slider.
            if(!silent){
                this.slider.setValue(v, animate);
            }
            return Ext.form.SliderField.superclass.setValue.call(this, this.slider.getValue());
        },

        /**
         * Gets the current value for this field.
         * @return {Number} The current value.
         */
        getValue : function(){
            return this.slider.getValue();
        }
    });

    Ext.reg('sliderfield', Ext.form.SliderField);