@Override
    public void onChartDataChanged() {
        super.onChartDataChanged();
        final PieChartData data = dataProvider.getPieChartData();
        hasLabelsOutside = data.hasLabelsOutside();
        hasLabels = data.hasLabels();
        hasLabelsOnlyForSelected = data.hasLabelsOnlyForSelected();
        valueFormatter = data.getFormatter();
        hasCenterCircle = data.hasCenterCircle();
        centerCircleScale = data.getCenterCircleScale();
        centerCirclePaint.setColor(data.getCenterCircleColor());
        if (null != data.getCenterText1Typeface()) {
            centerCircleText1Paint.setTypeface(data.getCenterText1Typeface());
        }
        centerCircleText1Paint.setTextSize(ChartUtils.sp2px(scaledDensity, data.getCenterText1FontSize()));
        centerCircleText1Paint.setColor(data.getCenterText1Color());
        centerCircleText1Paint.getFontMetricsInt(centerCircleText1FontMetrics);
        if (null != data.getCenterText2Typeface()) {
            centerCircleText2Paint.setTypeface(data.getCenterText2Typeface());
        }
        centerCircleText2Paint.setTextSize(ChartUtils.sp2px(scaledDensity, data.getCenterText2FontSize()));
        centerCircleText2Paint.setColor(data.getCenterText2Color());
        centerCircleText2Paint.getFontMetricsInt(centerCircleText2FontMetrics);

        onChartViewportChanged();
    }
Default renderer for PieChart. PieChart doesn't use viewport concept so it a little different than others chart
types.
hellocharts-library/src/lecho/lib/hellocharts/renderer/PieChartRenderer.java