Node.js PNG缓冲区获取未知图像格式错误

您编写的".png"图像部分错误.

Js运行在非阻塞I/O模型上，这意味着它不需要等到读写文件系统等操作完成后才继续下一行代码.这对性能很有好处，但当一个操作依赖于另一个操作的完成时，可能会导致问题.

在您的函数中，您将使用fs.WriteFile()将条形码图像写入磁盘.此方法是异步的-它启动写入过程，然后立即继续，而不是等待文件写入完成.

函数的作用是异步的.

这意味着它启动文件写入过程，然后立即移动到下一行代码，而无需等待文件写入完成.

因此，下一步"fs.createWriteStream()"没有机会读取完成的图像. 因此，此代码将创建正确的PDF文件.

const PDFDocument = require("pdfkit");
const bwipjs = require("bwip-js");
const fs = require("fs");

function generateCustomerInvoice(invoiceData) {
    const id = invoiceData.invoiceNumber;
    const barcodeDir = "./barcodes/";
    const pdfDir = "./pdfs/customer/";

    if (!fs.existsSync(barcodeDir)) {
        fs.mkdirSync(barcodeDir, { recursive: true });
    }

    if (!fs.existsSync(pdfDir)) {
        fs.mkdirSync(pdfDir, { recursive: true });
    }

    bwipjs.toBuffer({
        bcid: "code128",
        text: id,
        scale: 3,
        height: 10,
        includetext: true,
        textxalign: "center",
    })
        .then((png) => {
            return new Promise((resolve, reject) => {
                fs.writeFile("./barcodes/" + id + ".png", png, (err) => {
                    if (err) {
                        console.error("Error writing file:", err);
                        reject(err);
                    } else {
                        console.log("Barcode Finished");
                        resolve();
                    }
                });
            });
        })
        .then(() => {
            const doc = new PDFDocument({ autoFirstPage: false });
            doc.pipe(fs.createWriteStream("./pdfs/customer/" + id + ".pdf"));
            doc.addPage({ size: "A5", margin: 20 });

            doc.fontSize(12).text("Customer Invoice", 40, 30);

            doc.image("./barcodes/" + id + ".png", 40, 60, { width: 150 });

            doc.fontSize(10).text(`Customer Name: ${invoiceData.customerName}`, 40, 130);

            const tableTop = 160;
            doc.fontSize(10);
            doc.text("Description", 40, tableTop);
            doc.text("Quantity", 200, tableTop);
            doc.text("Price", 280, tableTop);
            doc.text("Total", 360, tableTop);

            let verticalPosition = tableTop;
            invoiceData.items.forEach(item => {
                verticalPosition += 20;
                doc.text(item.description, 40, verticalPosition);
                doc.text(item.quantity, 200, verticalPosition);
                doc.text(`$${item.price.toFixed(2)}`, 280, verticalPosition);
                doc.text(`$${(item.quantity * item.price).toFixed(2)}`, 360, verticalPosition);
            });

            doc.end();
        })
        .catch((err) => {
            console.error("Error in PDF generation: ", err);
        });
}

generateCustomerInvoice({
    customerName: "Tom Cruise",
    invoiceNumber: "INV-10001",
    items: [
        { description: "Item 1", quantity: 2, price: 100.00 },
        { description: "Item 2", quantity: 5, price: 50.00 }
    ],
});

Result

更多详细信息请参见here