如何在 Flutter 中生成 PDF 文件的二维码

Question

我已使用此解决方案How Can I generate QR code and Show it on a PDF page in Flutter，但仍然无法打印二维码。

我的代码：

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

这是我的功能：

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: +923058431046",
              style: pdf.TextStyle(fontSize: 24),
              textAlign: pdf.TextAlign.center),
          pdf.SizedBox(height: 10),

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

    return doc.save();
  }

除 QR 码外，所有内容都可以正常打印，并且在该特定行，此错误会显示在终端：

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

Answer 1

我在显示 "has no Unicode support..." 行时遇到问题，以修复我在项目中创建了一个文件夹字体并添加了一些真实类型的字体，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，错误消失了，如下所示：

Page(theme: myTheme,...)

我不确定是不是同样的情况，但我认为你应该试试。