private void drawSlice(Canvas canvas, SliceValue sliceValue, float lastAngle, float angle, int mode) {
        sliceVector.set((float) (Math.cos(Math.toRadians(lastAngle + angle / 2))),
                (float) (Math.sin(Math.toRadians(lastAngle + angle / 2))));
        normalizeVector(sliceVector);
        drawCircleOval.set(originCircleOval);
        if (MODE_HIGHLIGHT == mode) {
            // Add additional touch feedback by setting bigger radius for that slice and darken color.
            drawCircleOval.inset(-touchAdditional, -touchAdditional);
            slicePaint.setColor(sliceValue.getDarkenColor());
            canvas.drawArc(drawCircleOval, lastAngle, angle, true, slicePaint);
        } else {
            slicePaint.setColor(sliceValue.getColor());
            canvas.drawArc(drawCircleOval, lastAngle, angle, true, slicePaint);
        }
    }
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