请使用win32com向excel插入图片并转成pdf

我想在excel每个sheet的底部插入一张jpg，并且将这个sheet打印成“所有列为一页”的pdf，但我无法获取到excel底部的坐标；或者我能否通过获取最底部的单元格，以单元格为坐标进行插入，如果是这样请问该如何操作？
底下附上我的代码，仅供参考，请指点

import os
from win32com.client import Dispatch, constants, gencache, DispatchEx


class PDFConverter:
    def __init__(self, pathname, export='.'):
        self._handle_postfix = ['xls', 'xlsx']           #'doc', 'docx', 'ppt', 'pptx', 
        self._filename_list = list()
        folder = r'C:\Users\rz\Desktop\新建文件夹\PDF' 
        self._export_folder = os.path.join(os.path.abspath('.'),folder)
        if not os.path.exists(self._export_folder):
                os.mkdir(self._export_folder)
        self._enumerate_filename(pathname)
    
    def _enumerate_filename(self, pathname):
        '''
        读取所有文件名
        '''
        full_pathname = os.path.abspath(pathname)
        if os.path.isfile(full_pathname):
            if self._is_legal_postfix(full_pathname):
                self._filename_list.append(full_pathname)
            else:
                raise TypeError('文件 {} 后缀名不合法！仅支持如下文件类型：{}。'.format(pathname, '、'.join(self._handle_postfix)))
        elif os.path.isdir(full_pathname):
            for relpath, _, files in os.walk(full_pathname):
                for name in files:
                    filename = os.path.join(full_pathname, relpath, name)
                    if self._is_legal_postfix(filename):
                        self._filename_list.append(os.path.join(filename))
        else:
            raise TypeError('文件/文件夹 {} 不存在或不合法！'.format(pathname))

    def _is_legal_postfix(self, filename):
        return filename.split('.')[-1].lower() in self._handle_postfix and not os.path.basename(filename).startswith('~')
    
    def run_conver(self):
        '''
        进行批量处理，根据后缀名调用函数执行转换
        '''
        print('需要转换的文件数：', len(self._filename_list))
        for filename in self._filename_list:
            postfix = filename.split('.')[-1].lower()
            funcCall = getattr(self, postfix)
            print('原文件：', filename)
            funcCall(filename)
        print('转换完成！')
    
    def xls(self, filename):
        '''
        xls 和 xlsx 文件转换
        '''
        name = os.path.basename(filename).split('.')[0] + '.pdf'
        exportfile = os.path.join(self._export_folder, name)
        xlApp = DispatchEx("Excel.Application")
        xlApp.Visible = False    
        xlApp.DisplayAlerts = 0   
        books = xlApp.Workbooks.Open(filename,False)
        books.ExportAsFixedFormat(0, exportfile)
        books.Close(False)
        print('保存 PDF 文件：', exportfile)
        xlApp.Quit()
    



if __name__ == "__main__":
    
    # 支持文件夹批量导入
    folder = r'C:\Users\rz\Desktop\新建文件夹' 
    pathname = os.path.join(os.path.abspath('.'), folder)
    


    pdfConverter = PDFConverter(pathname)
    pdfConverter.run_conver()