Camera: another update API for external camera

        /**

         * Gets the focal length (in millimeter) of the camera.

         *

         * @return the focal length. This method will always return a valid

         *         value.

         * @return the focal length. Returns -1.0 when the device

         *         doesn't report focal length information.

         */

        public float getFocalLength() {

            return Float.parseFloat(get(KEY_FOCAL_LENGTH));