/**
 * @class Ext.chart.Navigation
 *
 * Handles panning and zooming capabilities.
 * 
 * Used as mixin by Ext.chart.Chart.
 */
Ext.define('Ext.chart.Navigation', {

    constructor: function() {
        this.originalStore = this.store;
    },
    
    //filters the store to the specified interval(s)
    setZoom: function(zoomConfig) {
        var me = this,
            store = me.substore || me.store,
            bbox = me.chartBBox,
            len = store.getCount(),
            from = (zoomConfig.x / bbox.width * len) >> 0,
            to = Math.ceil(((zoomConfig.x + zoomConfig.width) / bbox.width * len)),
            recFieldsLen, recFields = [], curField, json = [], obj;
        
        store.each(function(rec, i) {
            if (i < from || i > to) {
                return;
            }
            obj = {};
            //get all record field names in a simple array
            if (!recFields.length) {
                rec.fields.each(function(f) {
                    recFields.push(f.name);
                });
                recFieldsLen = recFields.length;
            }
            //append record values to an aggregation record
            for (i = 0; i < recFieldsLen; i++) {
                curField = recFields[i];
                obj[curField] = rec.get(curField);
            }
            json.push(obj);
        });
        me.store = me.substore = Ext.create('Ext.data.JsonStore', {
            fields: recFields,
            data: json
        });
        me.redraw(true);
    },

    restoreZoom: function() {
        this.store = this.substore = this.originalStore;
        this.redraw(true);
    }
    
});