如何使用带有节点js的pdfkit管道流

Question

在PDFkit 0.5之前 - 以下对我有用(通过pdfkit生成pdf /通过ipp打印到CUPS):

var ipp = require("ipp");
var PDFDocument = require("pdfkit");

var doc = new PDFDocument;
doc.text("Hello World");

doc.output(function(pdf)){
    var printer = ipp.Printer("http://127.0.0.1:631/printers/1");
    var file = {
        "operation-attributes-tag":{
            "requesting-user-name": "User",
        "job-name": "Print Job",
        "document-format": "application/pdf"
        },
        data: new Buffer(pdf, "binary")
    };

    printer.execute("Print-Job", file, function (err, res) {
        console.log("Printed: "+res.statusCode);
    });
}

从PDFkit 0.5开始 - 该output方法已被弃用 - 但我似乎无法找到在pipe我的场景中使用新方法的示例.如果我没有使用浏览器,我还需要像blob-stream这样的模块吗？

Answer 1

由于pdfkit PDFDocument现在是一个流,您必须缓冲来自缓冲区的数据:

var ipp = require("ipp");
var PDFDocument = require("pdfkit");

var doc = new PDFDocument;
doc.text("Hello World");

var buffers = [];
doc.on('data', buffers.push.bind(buffers));
doc.on('end', function () {
    var printer = ipp.Printer("http://127.0.0.1:631/printers/1");
    var file = {
        "operation-attributes-tag":{
            "requesting-user-name": "User",
        "job-name": "Print Job",
        "document-format": "application/pdf"
        },
        data: Buffer.concat(buffers)
    };

    printer.execute("Print-Job", file, function (err, res) {
        console.log("Printed: "+res.statusCode);
    });
});
doc.end();

或者你可以使用concat-stream模块之类的东西:

var ipp = require("ipp");
var PDFDocument = require("pdfkit");
var concat = require("concat-stream");

var doc = new PDFDocument;
doc.text("Hello World");

doc.pipe(concat(function (data) {
    var printer = ipp.Printer("http://127.0.0.1:631/printers/1");
    var file = {
        "operation-attributes-tag":{
            "requesting-user-name": "User",
        "job-name": "Print Job",
        "document-format": "application/pdf"
        },
        data: data
    };

    printer.execute("Print-Job", file, function (err, res) {
        console.log("Printed: "+res.statusCode);
    });
}));
doc.end();