xtermjs/xterm.js

Infinite loop when drawing large ligatures to char atlas

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#4,362 创建于 2023年1月2日

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 (1 评论) (0 反应) (0 负责人)TypeScript (16,196 star) (1,574 fork)batch import
area/addon/ligaturesarea/addon/webglhelp wantedtype/bug

描述

some fonts provide extremely long ligatures, e.g. Fira Code for =================================================== The char atlas code tries to find a row to fit it but fails and gets stuck in an infinite loop https://github.com/xtermjs/xterm.js/blob/fe8981766769c19ab1903dffa19f1a64ad83da13/src/browser/renderer/shared/TextureAtlas.ts#L792-L799 ^Here we're checking if there's room on the current row and creating a new one if not.

Details

  • Browser and browser version: chrome 108
  • OS version: macOS 12
  • xterm.js version: 5.1.0 (also on latest master branch)

Steps to reproduce

  1. Install Fira Code font, Run the xterm demo and enable ligatures
  2. start typing =
  3. Keep looking at the char atlas drawn below, once the glyph is almost the same width as char atlas, typing the next = will freeze everything.

贡献者指南

技术栈
typescript
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。
stale
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
TypeScriptCanvas renderingTexture atlas concept
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 function at src/browser/renderer/shared/TextureAtlas.ts lines 792-799. The loop currently creates a new row but does not handle the case where the glyph width exceeds the atlas width, leading to an infinite loop. Consider adding a maximum row attempt check or ensuring that if a new row is still too small, the glyph is skipped or an error is thrown. Review the Canvas rendering logic to understand row dimensions.