@ioffice/svg2png

SVG-to-PNG Converter Using Chromium

You have a SVG file. For whatever reason, you need a PNG. svg2png can help.

const fs = require("pn/fs"); // https://www.npmjs.com/package/pn
const svg2png = require("svg2png");

svg2png("~/test.svg")
    .then(buffer => fs.writeFile("dest.png", buffer))
    .catch(e => console.error(e));

In the above example, we use the width and height attributes specified in the SVG file to automatically determine the size of the SVG. You can also explicitly set the size:

svg2png(url, { width: 300, height: 400 })
    .then(buffer => ...)
    .catch(e => console.error(e));

This is especially useful for images without width or heights. You can even specify just one of them and (if the image has an appropriate viewBox) the other will be set to scale.

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Sync variant

There's also a sync variant, for use in your shell scripts:

const outputBuffer = svg2png.sync(url, options);

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How the conversion is done

svg2png uses puppeteer to render your SVGs using a headless Chromium instance. I have found this to produce much more accurate renderings than other solutions like GraphicsMagick or Inkscape. Plus, it's easy to install cross-platform since it downloads Chromium on install so you don't even need to have it in your PATH.

Exact resizing behavior

Previous versions of svg2png attempted to infer a good size based on the width, height, and viewBox attributes. As of our 3.0 release, we attempt to stick as close to the behavior of loading a SVG file in your browser as possible. The rules are:

• Any width or height attributes that are in percentages are ignored and do not count for the subsequent rules.
• The dimensions option { width, height } overrides any width or height attributes in the SVG file, including for the subsequent rules. If a key is missing from the dimensions object (i.e. { width } or { height }) the corresponding attribute in the SVG file will be deleted.
• width and height attributes without a viewBox attribute cause the output to be of those dimensions; this might crop the image or expand it with empty space to the bottom and to the right.
• width and/or height attributes with a viewBox attribute cause the image to scale to those dimensions. If the ratio does not match the viewBox's aspect ratio, the image will be expanded and centered with empty space in the extra dimensions. When a viewBox is present, one of either width or height can be omitted, with the missing one inferred from the viewBox's aspect ratio.
• When there are neither width nor height attributes, the promise rejects.

One thing to note is that svg2png does not and cannot stretch your images to new aspect ratios.

CLI

This package comes with a CLI version as well; you can install it globally with npm install svg2png -g. Use it as follows:

$ svg2png --help
Converts SVGs to PNGs, using Chromium

svg2png input.svg [--output=output.png] [--width=300] [--height=150]

Options:
  -o, --output  The output filename; if not provided, will be inferred  [string]
  -w, --width   The output file width, in pixels                        [string]
  -h, --height  The output file height, in pixels                       [string]
  --help        Show help                                              [boolean]
  --version     Show version number                                    [boolean]

Node.js requirements

svg2png uses the latest in ES2017 features, and as such requires a recent version of Node.js. Only the 8.x series onward is supported.

TODO:

Create the tests for the cli