processing/p5.js

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

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#8,771 创建于 2026年5月8日

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 (12 评论) (1 反应) (0 负责人)JavaScript (20,784 star) (3,178 fork)batch import
Area:TypographyBugHelp Wanted

描述

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.

贡献者指南

技术栈
javascript
领域
frontend
议题类型
bug
难度面向新贡献者的预计实现难度，1 表示很小改动，5 表示专家级工作。
3
预计时间有经验贡献者完成调查、实现、测试并准备 pull request 的粗略时间范围。
1-3 hours
活动状态议题当前的可参与程度：新鲜、活跃、陈旧、阻塞或等待维护者输入。
fresh
清晰度议题是否清楚说明期望改动、验收标准和下一步。
clear
前置要求
Familiarity with p5.js Typography codeBasic understanding of canvas text metrics
新手友好度1-100 的估计分数，表示该议题对首次贡献者的友好程度。
60
研究方向
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.
textAscent() and textDescent() broken if textSize > 200 · processing/p5.js#8771 | Good First Issue