Pretext Optimizer

Reduce DOM measurement overhead during rendering, improving performance for large documents.

Version: 1.2.2 | Requires: Obsidian 1.10+

中文文档 · 中文文档 — see README_zh.md for the Chinese version.

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What it does

When you open a note, Obsidian needs to measure the actual occupied size of text to set heights — this is called DOM measurement. Every measurement touches the render tree and is expensive. Pretext calculates heights at build time and sets min-height directly, letting the browser skip measurement.

Effects:

• Faster first-paint on long documents
• Reduced reflow during scroll
• Particularly helpful for large documents (callouts, blockquotes, tables)

How it works

1. Preview mode: MarkdownPostProcessor captures the render, uses Pretext to compute height, sets min-height
2. Edit mode: CodeMirrorExtension does the same on editor lines (Obsidian 1.5+)
3. Smart cache: Identical text + identical font results are cached, avoiding repeated computation

Performance optimizations (v1.2.1)

• Local scanning: observeHeavyElements() now only scans the visible content area, not the whole document
• RAF throttling: DOM-mutation triggers are throttled via requestAnimationFrame to prevent duplicate processing
• Batched processing: Preview mode processes at most 5 elements per batch, using requestIdleCallback for scheduling

Install

In Obsidian (after approval)

1. Open Settings → Community plugins
2. Search for "Pretext Optimizer"
3. Click Install, then Enable

BRAT (recommended for beta)

1. Install the BRAT plugin
2. Command palette → BRAT: Add a beta plugin → enter wuyifan-code/Obsidian-pretext
3. Enable "Pretext Optimizer"

Manual

1. Download the latest release
2. Extract to .obsidian/plugins/obsidian-pretext/
3. Restart Obsidian and enable the plugin

Development

npm install
npm test         # run tests
npm run typecheck
npm run build    # build main.js

Project layout

src/
├── analysis/           # tokenization, punctuation, whitespace
│   ├── segmentation.ts
│   ├── punctuation.ts
│   └── whitespace.ts
├── hooks/              # Obsidian extension points
│   ├── CodeMirrorExtension.ts
│   ├── MarkdownPostProcessor.ts
│   └── HeavyElementOptimizer.ts
├── PretextManager.ts   # Pretext core manager
└── MeasurementCache.ts # measurement result cache

Tech stack

• TypeScript + Vitest
• Pretext by Cheng Lou — MIT License
• CodeMirror 6 (built into Obsidian)

License

MIT — see LICENSE.

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Powered by Pretext by Cheng Lou

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中文文档

减少渲染时的 DOM 测量开销，提升大型文档的渲染性能。

版本: 1.2.2 | 要求: Obsidian 1.10+

这个插件做什么

在你的笔记打开时，Obsidian 需要测量文本的实际占用来设置高度——这叫 DOM 测量。每次测量都要访问渲染树，开销很大。Pretext 在构建时就算好高度，直接设置 min-height，让浏览器跳过测量。

效果：

• 长文档首次渲染更快
• 滚动时减少 reflow
• 大文档（callout、blockquote、表格）特别受益

如何工作

1. 预览模式: MarkdownPostProcessor 捕获渲染，用 Pretext 计算高度，设置 min-height
2. 编辑模式: CodeMirrorExtension 在编辑器行上做同样处理（Obsidian 1.5+）
3. 智能缓存: 相同文本+相同字体的结果缓存起来，避免重复计算

性能优化 (v1.2.1)

• 局部扫描: observeHeavyElements() 现在只扫描可见内容区域，不扫整个 document
• RAF 节流: DOM 变化触发时用 requestAnimationFrame 节流，防止重复处理
• 分批处理: 预览模式每批最多 5 个元素，用 requestIdleCallback 分批处理

安装

BRAT（推荐 Beta 安装）

1. 安装 BRAT 插件
2. 命令面板 → BRAT: Add a beta plugin → 输入 wuyifan-code/Obsidian-pretext
3. 启用 "Pretext Optimizer"

手动

1. 下载最新 release
2. 解压到 .obsidian/plugins/obsidian-pretext/
3. 重启 Obsidian，启用插件

开发

npm install
npm test        # 运行测试
npm run typecheck
npm run build   # 构建 main.js

项目结构

src/
├── analysis/           # 分词、标点、空白处理模块
│   ├── segmentation.ts
│   ├── punctuation.ts
│   └── whitespace.ts
├── hooks/              # Obsidian 扩展点
│   ├── CodeMirrorExtension.ts
│   ├── MarkdownPostProcessor.ts
│   └── HeavyElementOptimizer.ts
├── PretextManager.ts   # Pretext 核心管理
└── MeasurementCache.ts # 测量结果缓存

技术栈

• TypeScript + Vitest
• Pretext (Cheng Lou) — MIT License
• CodeMirror 6 (Obsidian 内置)

许可证

MIT License。