![]() ![]() Positioning Textīy default, the pdfkit module keeps track of where text should be added to the document, essentially print each call to the text() function in a new line. Let's take a look at some of the features it offers. Of course, pdfkit allows us to do much more than just add unformatted text to a document. I.e - all windows with that PDF file must be closed or the program will throw an error. Note: Before attempting to overwrite an existing PDF file, it must be free. When we run the code, a PDF file called SampleDocument.pdf is created in the root folder of our project: $ node index.js Of course, we'll want to end() the stream in the end. Once created, we can add contents to it, via the text function. We're using the pipe() function to do this and save the resulting SampleDocument.pdf into our root directory. If you're not familiar with how streams work, check out our Introduction to Node.js Streams. We'll be piping that stream into a writeable stream to save the file. PdfDoc.pipe(fs.createWriteStream( 'SampleDocument.pdf')) įirst, we import the required modules, after which, we instantiate the PDFDocument. We'll pipe the contents of our PDF file into a fs's writeable stream to save it. To create a PDF document, we will need to import the fs (file system) module as well. To use the module in the project, we'll import it via require(): const PDFDocument = require( 'pdfkit') Then, let's install pdfkit: $ npm install pdfkit Let's create a project directory, cd into it and initialize the Node project with default settings: $ mkdir pdfkit-project $ cd pdfkit-project $ npm init -y PDFKit is a JavaScript PDF generation library for Node.js that provides an easy way to create multi-page, printable PDF documents. In this article, we will discuss how to generate PDF files in NodeJS using the NPM package pdfkit. In dynamic web applications, you might need to export data into a document and PDF is usually a popular option. It's not really finished or well tested at the moment, but if you feel like taking a look at it feel free! Seems like it might be useful for react-pdf and other similar libraries that want to do text layout.The PDF format is one of the most common document formats for transferring information. I've been meaning to clean that up and release it, but I don't really have time. I worked on this problem a bit in a while ago. It basically only works well for unidirectional text in a single font, and you'll hit that limitation very quickly for anything complicated. ![]() PDFKit currently implements an extremely basic version of this without a lot of the steps. Finalize lines - Apply text-decoration, hanging punctuation, etc.Īs you can see, there are a lot of steps here to do text layout correctly in a Unicode friendly way.Justification - If justification is enabled, adjust the spacing between each glyph on each line to justify it.Apply tab stops - make sure the tab characters on each line are the correct width so that they align with tab stops.Bidi reordering - Using the bidi information computed earlier, reorder the generated glyph runs on each line according to the bidi algorithm.Line breaking - Using the generated glyph runs for the paragraph, break into lines using the Unicode line breaking algorithm.This can be done using - the library PDFKit already uses. Font shaping - for each run of text, convert characters to glyphs from that font.Break the text into runs of similar scripts. Script itemization - in Unicode, each character is part of a script.See for a way to do font substitution using the native OS. This produces "runs" of text in the same font. Font substitution - check whether the user-defined font actually supports each character the user wants to render.Get bidi runs and compute paragraph direction - This is the unicode bidirectional algorithm.Split text into paragraphs - the following steps are applied to each paragraph.Here's the basic text layout algorithm most text systems (like word processors, operating systems, web browsers, etc.) follow: Getting the details right in a way that works for all languages is crazy challenging. Text layout is actually a really hard problem - way harder than it seems at first glance. You'll need to do the layout first, and then once the final glyphs and their positions are known, send them to PDFKit for rendering. PDFKit basically immediately writes content to the file as you are adding it, but for justification, especially when multiple styles or fonts can be inlined, you need a multi-pass layout algorithm. I would definitely recommend doing this somewhere higher in the stack than PDFKit.
0 Comments
Leave a Reply. |