Automattic/node-canvas

`Image#src=` does not work with object URL (`onload` never called, cannot be drawn on 2d context)

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#2,525 opened on Jul 16, 2025

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Good first issue

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Description

import { Image } from 'canvas';
import { readFileSync } from 'fs';

const file = readFileSync('test.png');
const objectUrl = URL.createObjectURL(new Blob([file], { type: 'image/png' }));
const image = new Image();
image.onload = () => {
	URL.revokeObjectURL(objectUrl);
	console.log('in onload: complete =', image.complete); // never called
};
image.src = objectUrl;
console.log('immediately after setting src: complete =', image.complete); // true

If you try to draw an image with src being an object URL on a 2d context, you get Error: Image given has not completed loading.

Environment:

  • Node.js 22.14.0
  • canvas 3.1.2

Contributor guide

Research direction
Investigate why `Image#src` with object URLs fails to trigger `onload` and why `complete` is set to true immediately. Check the node canvas internals for object URL handling and the loading lifecycle.
Tech stack
javascript
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.
Active
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
Clear
Prerequisites
GitNode.js
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
60