GPUI Web Platform (WebAssembly/WebGPU)

Note: This implementation was developed with assistance from Claude Code.

This fork adds web platform support to GPUI, the GPU-accelerated UI framework from Zed.

Live Demo →

Overview

GPUI now runs in the browser via WebAssembly with support for both WebGPU and WebGL2 backends (via wgpu's automatic fallback). All 31 GPUI examples work in modern browsers.

What Works

• Text rendering (via cosmic-text)
• Images, GIFs, and SVGs
• Animations and transitions
• Mouse input (click, hover, drag & drop)
• Keyboard input and text editing
• Scrolling and uniform lists
• Gradients, shadows, patterns, and paths
• Flexbox and grid layouts

What's Not Implemented

• Clipboard (read/write)
• File dialogs
• Native menus
• Multi-window support
• Drag & drop to/from OS

Technical Approach

The implementation adds a new platform module (crates/gpui/src/platform/web/) alongside the existing macOS, Linux, and Windows implementations. Key components:

Component	Implementation
Rendering	WebGPU or WebGL2 via wgpu (auto-detected)
Text	cosmic-text (same as Linux)
Event loop	requestAnimationFrame via wasm-bindgen
Async runtime	futures crate (no smol in WASM)
Time	web_time::Instant (no std::time::Instant)

Core Changes

Changes to existing GPUI code are minimal and cfg-gated:

1. Async GPU Init: WebGPU requires async request_adapter().await - added is_renderer_ready() check to defer first draw
2. No Blocking: WASM can't block - executor.block() panics with helpful message
3. Time APIs: std::time::Instant unavailable - conditional web_time import
4. HTTP Client: Web fetch API stub replaces native http_client

All native platforms remain unchanged. See crates/gpui/src/platform/web/CHANGES.md for detailed documentation.

Building for Web

Prerequisites

rustup target add wasm32-unknown-unknown
cargo install wasm-pack

Build an Example

cd crates/gpui_web_example
wasm-pack build --target web --out-dir www/pkg

Serve Locally

cd www && python3 -m http.server 8081

Open http://localhost:8081 in Chrome or Edge (WebGPU required).

Project Structure

crates/
├── gpui/
│   └── src/
│       └── platform/
│           ├── mac/          # macOS (Metal)
│           ├── linux/        # Linux (Vulkan)
│           ├── windows/      # Windows (DirectX)
│           └── web/          # NEW: Web (WebGPU)
│               ├── platform.rs
│               ├── window.rs
│               ├── renderer.rs
│               ├── atlas.rs
│               ├── text_system.rs
│               ├── timer.rs
│               ├── http_client.rs
│               └── CHANGES.md
└── gpui_web_example/         # WASM build harness
    ├── src/lib.rs
    └── www/
        └── index.html

Stats

• ~5,300 lines of new web platform code
• 7 new files in platform/web/
• ~150 lines of changes to core GPUI (all cfg-gated)
• 0 changes to native platform behavior

Related Links

• Zed Web Tracking Issue
• GPUI Documentation
• Zed Repository

License

Same as Zed - see LICENSE.