private void normalizeVector(PointF point) {
        final float abs = point.length();
        point.set(point.x / abs, point.y / abs);
    }
Method draws single slice from lastAngle to lastAngle+angle, if mode = {@link #MODE_HIGHLIGHT} slice will be
darken
and will have bigger radius.
hellocharts-library/src/lecho/lib/hellocharts/renderer/PieChartRenderer.java