The source code

    Ext.chart.Chart.CHART_URL = '../../resources/charts.swf';

    Ext.onReady(function(){
        var store = new Ext.data.JsonStore({
            fields: ['season', 'total'],
            data: [{
                season: 'Summer',
                total: 150
            },{
                season: 'Fall',
                total: 245
            },{
                season: 'Winter',
                total: 117
            },{
                season: 'Spring',
                total: 184
            }]
        });

        new Ext.Panel({
            width: 400,
            height: 400,
            title: 'Pie Chart with Legend - Favorite Season',
            renderTo: 'container',
            items: {
                store: store,
                xtype: 'piechart',
                dataField: 'total',
                categoryField: 'season',
                //extra styles get applied to the chart defaults
                extraStyle:
                {
                    legend:
                    {
                        display: 'bottom',
                        padding: 5,
                        font:
                        {
                            family: 'Tahoma',
                            size: 13
                        }
                    }
                }
            }
        });
    });