如何在flutter中对PDF文件生成二维码

Question

我已经使用了这个解决方案如何生成QR码并将其显示在Flutter中的PDF页面上但仍然没有打印QR码。

我的代码：

  pdf.BarcodeWidget(
              color: PdfColor.fromHex("#000000"),
              barcode:pdf.Barcode.qrCode(), data: "My name is Bilal"
          ),

这是我的职责：

Future<Uint8List> func_generate_sale_pdf(PdfPageFormat format) {
    final doc = pdf.Document();

    doc.addPage(pdf.Page(build: (pdf.Context context) {
      return pdf.Center(
        child: pdf.Column(children: <pdf.Widget>[

          pdf.Text(config.app_name.toUpperCase(),
              style:
                  pdf.TextStyle(fontSize: 32, fontWeight: pdf.FontWeight.bold)),
          pdf.SizedBox(height: 25),
          pdf.Text(
              " ${languages.skeleton_language_objects[config.app_language]['for_enquiries_call']} : ${config.app_contacts}",
              style: pdf.TextStyle(fontSize: 22)),
          pdf.SizedBox(height: 5),
          pdf.Text("${config.app_po_box}", style: pdf.TextStyle(fontSize: 22)),
          pdf.SizedBox(height: 5),
          pdf.Text(
              "${languages.skeleton_language_objects[config.app_language]['receipt']} # ${receipt_data['receipt_no']}",
              style: pdf.TextStyle(fontSize: 20)),
          pdf.SizedBox(height: 5),
          pdf.Text("${receipt_data['date_time']}",
              style: pdf.TextStyle(fontSize: 20)),
          pdf.SizedBox(height: 30),
          pdf.Container(
            alignment: pdf.Alignment.topLeft,
            child: pdf.Text("${receipt_data['items_list'].toString()}",
                style: pdf.TextStyle(
                    fontSize: 22, fontWeight: pdf.FontWeight.normal),
                textAlign: pdf.TextAlign.left),
          ),
          pdf.SizedBox(height: 30),
          pdf.Container(
              child: pdf.Row(children: <pdf.Widget>[
            pdf.Expanded(
              flex: 1,
              child: pdf.Text(
                  languages.skeleton_language_objects[config.app_language]
                      ['total_amount'],
                  style: pdf.TextStyle(
                      fontSize: 20, fontWeight: pdf.FontWeight.bold),
                  textAlign: pdf.TextAlign.left),
            ),
            pdf.Expanded(
              flex: 1,
              child: pdf.Text("${receipt_data['total_amount']}",
                  style: pdf.TextStyle(fontSize: 20),
                  textAlign: pdf.TextAlign.right),
            ),
          ])),
          pdf.SizedBox(height: 10),
          pdf.Container(
              child: pdf.Row(children: <pdf.Widget>[
            pdf.Expanded(
              flex: 1,
              child: pdf.Text(
                  languages.skeleton_language_objects[config.app_language]
                      ['total_items'],
                  style: pdf.TextStyle(
                      fontSize: 20, fontWeight: pdf.FontWeight.bold),
                  textAlign: pdf.TextAlign.left),
            ),
            pdf.Expanded(
              flex: 1,
              child: pdf.Text("${receipt_data['total_items']}",
                  style: pdf.TextStyle(fontSize: 20),
                  textAlign: pdf.TextAlign.right),
            ),
          ])),
          pdf.SizedBox(height: 10),
          pdf.Container(
              height: 35,
              child: pdf.Row(children: <pdf.Widget>[
                pdf.Expanded(
                  flex: 1,
                  child: pdf.Text(
                      languages.skeleton_language_objects[config.app_language]
                          ['total_tax'],
                      style: pdf.TextStyle(
                          fontSize: 20, fontWeight: pdf.FontWeight.bold),
                      textAlign: pdf.TextAlign.left),
                ),
                pdf.Expanded(
                  flex: 1,
                  child: pdf.Text("${receipt_data['total_tax_amount']}",
                      style: pdf.TextStyle(fontSize: 20),
                      textAlign: pdf.TextAlign.right),
                ),
              ])),
          pdf.SizedBox(height: 35),
          pdf.Text(
              languages.skeleton_language_objects[config.app_language]
                  ['thant_you_and_come_again'],
              style: pdf.TextStyle(fontSize: 24)),


         //From here on, the compiler doesn't print anything.
          pdf.BarcodeWidget(
              color: PdfColor.fromHex("#000000"),
              barcode:pdf.Barcode.qrCode(), data: "My name is Bilal"
          ),
          pdf.Text("SkillzUPP Technologies: [phone]",
              style: pdf.TextStyle(fontSize: 24),
              textAlign: pdf.TextAlign.center),
          pdf.SizedBox(height: 10),

        ]),
      ); // Center
    }));

    return doc.save();
  }

除了二维码之外，一切都打印正常，并且在该特定行，此错误显示在终端上：

Helvetica-Bold has no Unicode support see https://github.com/DavBfr/dart_pdf/wiki/Fonts-Management

Answer 1

我在显示该行

"has no Unicode support..."

时遇到问题，以修复我在项目上创建了一个文件夹字体并向其中添加了一些真实类型字体，然后我为文档创建了一个 pdf 主题，如下所示：

var myTheme = ThemeData.withFont(
      base: Font.ttf(await rootBundle.load("fonts/OpenSans-Regular.ttf")),
      bold: Font.ttf(await rootBundle.load("fonts/OpenSans-Bold.ttf")),
      italic: Font.ttf(await rootBundle.load("fonts/OpenSans-Italic.ttf")),
      boldItalic:
          Font.ttf(await rootBundle.load("fonts/OpenSans-BoldItalic.ttf")),
    );

然后我在文档页面中使用了主题，错误就消失了，如下所示：

Page(theme: myTheme,...)

我不确定是否是同样的情况，但我认为你应该尝试一下。

Answer 2

import 'package:pdf/pdf.dart';
import 'package:pdf/widgets.dart' as pw;
import 'package:printing/printing.dart';

final fontData = await rootBundle.load("assets/fonts/OpenSans-Regular.ttf");
    final ttf = pw.Font.ttf(fontData);
    
    var theme = pw.ThemeData.withFont(base: ttf);
    final pdf = pw.Document(
        version: PdfVersion.pdf_1_5,
        theme: theme,
        compress: true
    );