Flutter如何在PopupMenuButton中使用对齐方式？

Question

我想使用对齐方式，因为我希望弹出动画从buttoncenter到topcenter。该怎么做？

from airflow.hooks.oracle_hook import OracleHook
import cx_Oracle
import sys

from datetime import datetime
from contextlib import closing
import os
os.environ['NLS_DATE_FORMAT'] = 'YYYY-MM-DD HH24:MI:SS'

class OracleHookTypeHandler(OracleHook):
    def __init__(self, oracle_conn_id):
        OracleHook.__init__(self, oracle_conn_id)

    # Override get_records from inherited class dbapihook
    def get_records(self, sql, parameters=None):
        """
        Executes the sql and returns a set of records.

        :param sql: the sql statement to be executed (str) or a list of
            sql statements to execute
        :type sql: str or list
        :param parameters: The parameters to render the SQL query with.
        :type parameters: mapping or iterable
        """
        if sys.version_info[0] < 3:
            sql = sql.encode('utf-8')

        with closing(self.get_conn()) as conn:
            with closing(conn.cursor()) as cur:
    
                cur.outputtypehandler = self.OutputHandler

                if parameters is not None:
                    cur.execute(sql, parameters)
                else:
                    cur.execute(sql)
                return cur.fetchall()

    # Dealing with invalid years in the database
    def DateTimeConverter(self, value):
        print('DateTimeConverter was called')
        if value.startswith('4712'):
            return None
        return datetime.strptime(value, '%Y-%m-%d %H:%M:%S')

    def OutputHandler(self, cursor, name, defaulttype, length, precision, scale):
        print('OutputHandler was called')
        if defaulttype == cx_Oracle.DATETIME:
            return cursor.var(cx_Oracle.STRING, arraysize=cursor.arraysize,
                              outconverter=self.DateTimeConverter)

def extract(extract_connection)
    # Return the extracted records
    extract_records_query = 'SELECT col1, col2, col3 FROM table'
    o_extract_hook = OracleHookTypeHandler(oracle_conn_id=extract_connection)
    print('Extract started')
    extract_records = o_extract_hook.get_records(sql=extract_records_query)
    return extract_records

这是我的简单代码。