code: 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);
          }
      }
docs: Method draws single slice from lastAngle to lastAngle+angle, if mode = {@link #MODE_HIGHLIGHT} slice will be
  darken
  and will have bigger radius.