canvg

What is canvg?

The canvg npm package is a versatile library that allows users to parse and render SVG (Scalable Vector Graphics) to a Canvas element in a browser or on the server-side using Node.js. It is particularly useful for converting SVGs into Canvas for manipulation, rendering, or exporting purposes.

What are canvg's main functionalities?

Rendering SVG to Canvas

This code sample demonstrates how to load an SVG file, render it onto a Canvas, and then save the Canvas output as a PNG file. This is useful for server-side generation of images from SVG files.

const canvg = require('canvg');
const Canvas = require('canvas');
const fs = require('fs');

const canvas = Canvas.createCanvas(800, 600);
const ctx = canvas.getContext('2d');
const svg = fs.readFileSync('path/to/your/svgfile.svg', 'utf-8');
canvg(ctx, svg);

const out = fs.createWriteStream('path/to/output.png');
const stream = canvas.createPNGStream();
stream.pipe(out);

Manipulating SVG before rendering

This example shows how to manipulate SVG data by changing its color before rendering it to a Canvas. This is useful for dynamically altering the appearance of SVGs based on runtime conditions.

const canvg = require('canvg');
const Canvas = require('canvas');
const fs = require('fs');

const canvas = Canvas.createCanvas(800, 600);
const ctx = canvas.getContext('2d');
let svg = fs.readFileSync('path/to/your/svgfile.svg', 'utf-8');

// Modify SVG data
svg = svg.replace('fill:#000000', 'fill:#123456');

// Render modified SVG to canvas
canvg(ctx, svg);

Other packages similar to canvg

fabric

Fabric.js is a powerful and rich graphics library, allowing you to manipulate and render both SVG and Canvas elements. Compared to canvg, Fabric.js offers a broader set of features for interactive object model on canvas, including a full suite of interactive capabilities such as drag and drop, object manipulation, and events.

svg2canvas

svg2canvas is another library that focuses on converting SVG documents into Canvas elements. While similar in purpose to canvg, svg2canvas might have different implementation details or performance characteristics, making it a viable alternative depending on specific project requirements.

README

node-canvg

A port of canvg, which pareses svg input and renders the result to a canvas. http://code.google.com/p/canvg/

Usage

var canvg = require("canvg");
var Canvas = require("canvas");

var canvas = new Canvas();

canvg(canvas, '<svg>...</svg>');

/* and so on */

Todo

The canvg code is pretty much untouched. A lot of browser-specific code has to be removed or rewritten.