adjust image size with printer 58 mm or 80 mm

[YouSour]

hi, i just found your video, it is awesome, i wonder how to adjust image size with printer 58mm or 80 mm ? thank in advance
here : example code what i using screenshot package to capture as image

import 'dart:math';
import 'package:flutter/material.dart';
import 'package:intl/intl.dart';

class TestPrinting extends StatelessWidget {
  const TestPrinting({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    ThemeData theme = Theme.of(context);
    List<Map<String, dynamic>> headerData = [
      {'លរ': Random().nextInt(100)},
      {'កាលបរិច្ឆេទ': DateFormat('yyyy-MM-dd – kk:mm').format(DateTime.now())},
      {'អ្នកលក់': 'Jhon'},
      {'អតិថជន': 'General'},
      {'លេខទូរស័ព្ទ': 'xxx xxx xxx'}
    ];

    List<String> dataTableHeader = ['ទំនិញ', 'ចំនួន', 'តម្លៃ', 'សរុប'];

    List<Map<String, dynamic>> dataTableBody = [
      {'item': 'item 1', 'qty': 1, 'price': 3.5, 'amount': 0},
      {'item': 'item 2', 'qty': 5, 'price': 2.5, 'amount': 0},
      {'item': 'item 3', 'qty': 1, 'price': 4.5, 'amount': 0},
    ];
    num total = 0;
    for (int i = 0; i < dataTableBody.length; i++) {
      total += dataTableBody[i]['price'] * dataTableBody[i]['qty'];
    }

    String formatTimeStampToString(DateTime dateTime, bool enableTime) {
      String formatStyle = 'dd/MM/yyyy';
      if (enableTime) formatStyle = 'dd/MM/yyyy hh:mm:ss a';
      return DateFormat(formatStyle).format(dateTime);
    }

    return Container(
      width: 300.0,
      child: Column(
        children: [
          Text(
            'RABBIT',
            style: theme.textTheme.headline4,
          ),
          Text(
            '# Street 153 រ៉ាប៊ីតតិចណូឡូជី, Battambang, Cambodia',
            style: theme.textTheme.headline5!.copyWith(fontSize: 16.0),
            textAlign: TextAlign.center,
          ),
          Text(
            'លេខទូរស័ព្ទ ៖ 070 550 880',
            style: theme.textTheme.headline5!.copyWith(fontSize: 16.0),
          ),
          const Divider(
            color: Colors.black,
            thickness: 1.5,
          ),
          Text('Invoice',
              style: theme.textTheme.headline5!
                  .copyWith(decoration: TextDecoration.underline)),
          for (int i = 0; i < headerData.length; i++)
            Row(
              mainAxisAlignment: MainAxisAlignment.spaceBetween,
              children: [
                Text(
                  headerData[i].keys.first.toUpperCase(),
                  style: theme.textTheme.bodyText2!
                      .copyWith(fontWeight: FontWeight.bold),
                ),
                Text(
                  headerData[i].entries.single.value.toString(),
                  style: theme.textTheme.headline6!,
                ),
              ],
            ),
          const SizedBox(height: 10.0),
          SizedBox(
            width: double.infinity,
            child: Theme(
              data: Theme.of(context).copyWith(dividerColor: Colors.black),
              child: DataTable(
                dividerThickness: 1.5,
                columns: <DataColumn>[
                  for (int i = 0; i < dataTableHeader.length; i++)
                    DataColumn(
                      label: Expanded(
                        child: Text(
                          dataTableHeader[i],
                          style: const TextStyle(
                              color: Colors.black,
                              // fontSize: 18.0,
                              fontStyle: FontStyle.italic,
                              fontWeight: FontWeight.bold),
                        ),
                      ),
                    ),
                ],
                rows: <DataRow>[
                  for (int i = 0; i < dataTableBody.length; i++)
                    DataRow(
                      cells: <DataCell>[
                        DataCell(
                          Text(
                            dataTableBody[i]['item'],
                            style: const TextStyle(fontWeight: FontWeight.bold),
                          ),
                        ),
                        DataCell(
                          Text(
                            dataTableBody[i]['qty'].toString(),
                            style: const TextStyle(fontWeight: FontWeight.bold),
                          ),
                        ),
                        DataCell(
                          Text(
                            dataTableBody[i]['price'].toString(),
                            style: const TextStyle(fontWeight: FontWeight.bold),
                          ),
                        ),
                        DataCell(
                          Text(
                            '${dataTableBody[i]['price'] * dataTableBody[i]['qty']}',
                            style: const TextStyle(fontWeight: FontWeight.bold),
                          ),
                        ),
                      ],
                    ),
                ],
              ),
            ),
          ),
          const Divider(color: Colors.black, thickness: 1.5),
          Column(
            crossAxisAlignment: CrossAxisAlignment.stretch,
            children: [
              RichText(
                textAlign: TextAlign.end,
                text: TextSpan(
                    text: 'សរុបទាំងអស់ : ',
                    style: theme.textTheme.bodyText2!
                        .copyWith(fontWeight: FontWeight.bold),
                    children: [
                      TextSpan(
                          text: '$total \$', style: theme.textTheme.headline6),
                    ]),
              )
            ],
          ),
          const Padding(
            padding: EdgeInsets.symmetric(vertical: 10.0),
            child: Text('សូមអរគុណជួបគ្នាម្តងទៀត...'),
          ),
        ],
      ),
    );
  }
}

image :