Automattic/node-canvas

RGB functions do not support real numbers

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#2339 opened on Jan 18, 2024

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Good first issueHelp wanted

Description

Issue

RGB colors that contain a real number are not supported, while in browsers this works. The official spec defines real numbers as a valid argument for the modern spec and browsers have supported this for several years so it would be nice to have consistency.

Steps to Reproduce

const { Canvas } = require('canvas');
const canvas = new Canvas();
const ctx = canvas.getContext('2d');

ctx.fillStyle = 'rgb(127,127.0,255)';
console.log(ctx.fillStyle); // output: #000000

ctx.fillStyle = 'rgb(127,127,255)';
console.log(ctx.fillStyle); // output: #7f7fff

I think this parsing may just have to be changed to floats?

Your Environment

  • Version of node-canvas: canvas@2.11.2
  • Environment: node v20.2.0 on macOS 14.2.1 (e.g. node 20.9.0 on macOS 14.1.1):

Contributor guide

Tech stack
javascriptnodejscpp
Domain
frontend
Issue type
bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
2
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
under 1 hour
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
fresh
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
clear
Prerequisites
C++CSS color parsing
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
90
Research direction
The issue is in the color parsing code in src/color.cc. The current implementation uses integer parsing; it needs to be changed to accept floating point numbers for RGB components. Look at line 163 and adjust the regex or parsing logic to handle decimals. Ensure compatibility with the CSS spec and existing integer behavior.