processing/p5.js

textAscent() and textDescent() broken if textSize > 200

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#8771 opened on May 8, 2026

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Area:TypographyBugHelp Wanted

Description

Most appropriate sub-area of p5.js?

  • Accessibility
  • Color
  • Core/Environment/Rendering
  • Data
  • DOM
  • Events
  • Image
  • IO
  • Math
  • Typography
  • Utilities
  • p5.strands
  • WebGL
  • DevOps, Build process, Unit testing
  • Internationalization (i18n)
  • Friendly Errors
  • Other (specify if possible)

p5.js version

1.11.13

Web browser and version

Chrome latest

Operating system

MacOS

Steps to reproduce this

Steps:

  1. textSize(201)
  2. textDescent()

Snippet:

https://editor.p5js.org/JuanIrache/sketches/2VVe5sram

When text size is larger than 200, trextAscent() and textDescent() break. Their total sum is correct, but they don't point to the top and bottom of the font any more.

Contributor guide

Tech stack
javascript
Domain
frontend
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.
fresh
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
clear
Prerequisites
Familiarity with p5.js Typography codeBasic understanding of canvas text metrics
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
60
Research direction
Investigate the implementation of textAscent() and textDescent() in p5.js's Typography module (likely in src/typography/p5.Font.js). Look for any hardcoded limits or calculations that break when textSize exceeds 200. Test with different font sizes to isolate the issue. Consider the native canvas measureText method's behavior at large sizes.