Printing a PDF file with Electron JS

Question

I am trying to create an Electron JS app that has the purpose to print letter size PDFs.

This is my snippet of code for printing:

win = new BrowserWindow         


        

Answer 1

I'm facing the same issue. It appears the PDF printing to a printer is just not implemented in Electron, despite it's been requested since 2017. Here is another related question on SO and the feature request on GitHub:

• Silent printing in electron
• Support printing in native PDF rendering

One possible solution might be to use Google PDFium and a wrapping NodeJS library which appears to allow conversion from PDF to a set of EMFs, so the EMFs can be printed to a local/network printer, at least on Windows.

As another viable option, this answer provides a simple C# solution for PDF printing using PdfiumViewer, which is a PDFium wrapper library for .NET.

I'm sill looking at any other options. Utilizing a locally installed instance of Acrobat Reader for printing is not an acceptable solution for us.

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UPDATED. For now, PDF.js solves the problem with rendering/previewing individual pages, but as to printing itself, it appears Electron (at the time of this posting) just lacks the proper printing APIs. E.g., you can't set paper size/landscape portrait mode etc. Moreover, when printing, PDF.js produces rasterized printouts - thanks to how HTML5 canvas work - unlike how Chrome PDF Viewer does it. Here is a discussion of some other PDF.js shortcomings.

So for now I think we might go on with a combination of PDF.js (for UI in the Electron's Renderer process) and PDFium (for actual printing from the Main process).

Based on Tim's answer, here's a version of the PDF.js renderer using ES8 async/await (supported as of the current version of Electron):

async function renderPDF(url, canvasContainer, options) {
    options = options || { scale: 1 };

    async function renderPage(page) {
        let viewport = page.getViewport(options.scale);
        let canvas = document.createElement('canvas');
        let ctx = canvas.getContext('2d');
        let renderContext = {
            canvasContext: ctx,
            viewport: viewport
        };

        canvas.height = viewport.height;
        canvas.width = viewport.width;
        canvasContainer.appendChild(canvas);

        await page.render(renderContext);
    }

    let pdfDoc = await pdfjsLib.getDocument(url);

    for (let num = 1; num <= pdfDoc.numPages; num++)
    {
        if (num > 1)
        {
            // page separator
            canvasContainer.appendChild(document.createElement('hr'));
        }
        let page = await pdfDoc.getPage(num);
        await renderPage(page);
    }
}