Automattic/node-canvas

Can't load svg with base64 image inside

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#1607 opened on Jun 13, 2020

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 (8 comments) (6 reactions) (0 assignees)JavaScript (9,524 stars) (1,140 forks)batch import
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Description

Issue or Feature

When load svg ( with base64 image inside ) file using function loadImage I get exception: GdkPixbuf-CRITICAL **: 13:03:49.842: gdk_pixbuf_get_width: assertion 'GDK_IS_PIXBUF (pixbuf)' failed

Steps to Reproduce

  1. Run following code to load svg file:
const fs = require('fs');
const { createCanvas, loadImage } = require('canvas');

async function nodeCanvasTest() {
  console.log('starting...');
  const canvas = createCanvas(400, 200);
  const ctx = canvas.getContext('2d');

  image = await loadImage('./input.svg');

  ctx.drawImage(image, 0, 0);
  var stream = canvas.createPNGStream();
  stream.pipe(fs.createWriteStream('output.png'));
  console.log('completed');
}

nodeCanvasTest();

Here is svg file:

input.svg.zip

  1. In the terminal run command: node server.js

  2. Get Error: GdkPixbuf-CRITICAL **: 13:03:49.842: gdk_pixbuf_get_width: assertion 'GDK_IS_PIXBUF (pixbuf)' failed

error_load_svg_with_base64

Your Environment

OS: MacOS Catalina 10.15.5 Node: v10.16.0 NPM: 6.9.2 Canvas: canvas@2.6.1

Expected:

SVG file is loaded & rendered normally.

Contributor guide

Tech stack
javascriptnodejs
Domain
backend
Issue type
bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
1-3 hours
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
stale
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
clear
Prerequisites
basic JavaScriptNode.js environmentSVG format knowledge
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
30
Research direction
The error occurs when loading an SVG with embedded base64 images. Investigate the loadImage function in src/canvas.cc or lib/canvas.js to see how SVG files are processed. The issue might be in the rsvg or librsvg integration. Examine the provided SVG file to understand its structure, and check how data URIs are handled. The fix may involve decoding base64 content before passing it to GdkPixbuf. Review the librsvg API to ensure base64 images are properly rendered.