private void drawCenterCircle(Canvas canvas) {
        final PieChartData data = dataProvider.getPieChartData();
        final float circleRadius = originCircleOval.width() / 2f;
        final float centerRadius = circleRadius * data.getCenterCircleScale();
        final float centerX = originCircleOval.centerX();
        final float centerY = originCircleOval.centerY();

        canvas.drawCircle(centerX, centerY, centerRadius, centerCirclePaint);

        // Draw center text1 and text2 if not empty.
        if (!TextUtils.isEmpty(data.getCenterText1())) {

            final int text1Height = Math.abs(centerCircleText1FontMetrics.ascent);

            if (!TextUtils.isEmpty(data.getCenterText2())) {
                // Draw text 2 only if text 1 is not empty.
                final int text2Height = Math.abs(centerCircleText2FontMetrics.ascent);
                canvas.drawText(data.getCenterText1(), centerX, centerY - text1Height * 0.2f, centerCircleText1Paint);
                canvas.drawText(data.getCenterText2(), centerX, centerY + text2Height, centerCircleText2Paint);
            } else {
                canvas.drawText(data.getCenterText1(), centerX, centerY + text1Height / 4, centerCircleText1Paint);
            }
        }
    }
Draw center circle with text if {@link PieChartData#hasCenterCircle()} is set true.
hellocharts-library/src/lecho/lib/hellocharts/renderer/PieChartRenderer.java