fix(image): make Buffer load synchronous and add decode() method by Brooooooklyn · Pull Request #1186 · Brooooooklyn/canvas

Brooooooklyn · 2025-12-25T08:57:25Z

Buffer src now fires onload/onerror synchronously (matches node-canvas)
Dimensions extracted from image header before events fire
Add decode() method returning Promise per W3C spec
Add 18 comprehensive decode() tests per WHATWG HTML spec

🤖 Generated with Claude Code

Co-Authored-By: Claude Opus 4.5 noreply@anthropic.com

Note

Introduces a decoding API and refactors image loading to be spec-aligned and race-safe.

Add Image.decode() Promise API with typings, and implement internal decoder_task using ScopedTask to expose a resolvable/rejectable decode promise
Buffer src behavior: complete=true immediately; dimensions parsed via imagesize before full decode; SVG decoded synchronously; onload now fires after bitmap decode so drawImage/createPattern work in handlers
Robust state/race handling: generation counter to abort stale loads, proper currentSrc semantics, clearing src='' resets state without events, broken images report 0 dimensions, external memory accounting fixed
AVIF fix: detect AVIF from Buffer by checking libavif first (before infer) and decode correctly
Loader update: load-image.js now waits for image.decode() before resolving
Types: index.d.ts adds decode() to Image
Dependencies: add imagesize (png/jpeg/gif/webp/heif) for header-based sizing
Tests: replace manual onload waits with await image.decode() where needed; add extensive WHATWG/W3C spec compliance and regression tests for complete/currentSrc, aborts, decode behavior, and AVIF

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Brooooooklyn · 2025-12-25T08:57:44Z

fix(image): make Buffer load synchronous and add decode() method #1186 👈 (View in Graphite)
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Pull request overview

This PR makes Buffer image loading synchronous (matching node-canvas behavior) by firing onload/onerror events synchronously after extracting dimensions from image headers. It also adds a decode() method that returns a Promise for the bitmap decoding operation, per the W3C HTML specification.

Key changes:

Natural dimensions are extracted from image headers using the imagesize crate before bitmap decoding
Buffer sources now fire onload/onerror synchronously with complete=true
Added decode() method returning Promise for async bitmap decoding
18 comprehensive tests for decode() behavior per WHATWG HTML spec

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 11 comments.

File	Description
src/image.rs	Adds natural_width/natural_height fields, synchronous Buffer loading with header parsing via imagesize, BufferDecodeTask for async bitmap decoding, and decode() method that returns the decoder task promise
test/image.spec.ts	Updates existing tests for new synchronous Buffer behavior and adds 18 new tests covering decode() method per W3C spec
Cargo.toml	Adds imagesize dependency for fast image header parsing without full decoding

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- Buffer src now fires onload/onerror synchronously (matches node-canvas) - Dimensions extracted from image header before events fire - Add decode() method returning Promise per W3C spec - Add 18 comprehensive decode() tests per WHATWG HTML spec 🤖 Generated with [Claude Code](https://claude.com/claude-code) Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Copilot AI review requested due to automatic review settings December 25, 2025 08:57

Copilot started reviewing on behalf of Brooooooklyn December 25, 2025 08:57 View session

Copilot AI reviewed Dec 25, 2025

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