@bun-win32/mscms

Zero-dependency, zero-overhead Win32 MSCMS bindings for Bun on Windows.

Overview

@bun-win32/mscms exposes the mscms.dll exports using Bun's FFI. It provides a single class, Mscms, which lazily binds native symbols on first use. You can optionally preload a subset or all symbols up-front via Preload().

The bindings are strongly typed for a smooth DX in TypeScript.

Features

• Bun-first ergonomics on Windows 10/11.
• Direct FFI to mscms.dll (ICC color profiles, color transforms, color space conversion, display calibration, and Windows Color System).
• In-source docs in structs/Mscms.ts with links to Microsoft Docs.
• Lazy binding on first call; optional eager preload (Mscms.Preload()).
• No wrapper overhead; calls map 1:1 to native APIs.
• Strongly-typed Win32 aliases (see types/Mscms.ts).

Requirements

• Bun runtime
• Windows 10 or later

Installation

bun add @bun-win32/mscms

Quick Start

import Mscms, { PROFILE_ACCESS, PROFILE_TYPE } from '@bun-win32/mscms';

// Preload the symbols you'll use
Mscms.Preload(['OpenColorProfileW', 'GetColorProfileHeader', 'CloseColorProfile']);

// Build a PROFILE struct that points at a filename
const path = Buffer.from('C:\\Windows\\System32\\spool\\drivers\\color\\sRGB Color Space Profile.icm\0', 'utf16le');
const profile = Buffer.alloc(24);
profile.writeUInt32LE(PROFILE_TYPE.PROFILE_FILENAME, 0);
profile.writeBigUInt64LE(BigInt(path.ptr!), 8);
profile.writeUInt32LE(path.byteLength, 16);

const hProfile = Mscms.OpenColorProfileW(profile.ptr!, PROFILE_ACCESS.PROFILE_READ, 0, 3 /* OPEN_EXISTING */);
if (hProfile !== 0n) {
  // 128-byte ICC profile header
  const header = Buffer.alloc(128);
  if (Mscms.GetColorProfileHeader(hProfile, header.ptr!)) {
    console.log('Profile size:', header.readUInt32LE(0));
  }
  Mscms.CloseColorProfile(hProfile);
}

[!NOTE] AI agents: see AI.md for the package binding contract and source-navigation guidance. It explains how to use the package without scanning the entire implementation.

Examples

Run the included examples:

bun run example:color-spectrum     # Animated sRGB <-> Adobe RGB gamut visualization
bun run example:profile-inspector  # Full ICC profile dump for every installed display profile

Notes

• Either rely on lazy binding or call Mscms.Preload().
• Windows only. Bun runtime required.
• SAL types & naming: nullability is in the type — Optional<T> (formally optional, SAL _*opt_) and Nullable<T> (plain [in]/[out] the docs say can be NULL), the null sentinel derived from T (null for pointers LP*/P*, 0n for handles/by-value addresses); direction is in the parameter name — _out (_Out_), _in_out (_Inout_), _In_ bare. See AI.md and the repo AGENTS.md.