@bun-win32/dwmapi

@bun-win32/dwmapi

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

Overview

@bun-win32/dwmapi exposes the dwmapi.dll exports using Bun's FFI. It provides a single class, Dwmapi, 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 dwmapi.dll (27 bindings covering Desktop Window Manager composition, blur, thumbnails, and window attributes).
• In-source docs in structs/Dwmapi.ts with links to Microsoft Docs.
• Lazy binding on first call; optional eager preload (Dwmapi.Preload()).
• No wrapper overhead; calls map 1:1 to native APIs.
• Strongly-typed Win32 aliases (see types/Dwmapi.ts).

Requirements

• Bun runtime
• Windows 10 or later

Installation

bun add @bun-win32/dwmapi

Quick Start

import Dwmapi, { WindowAttribute } from '@bun-win32/dwmapi';

// Optionally bind a subset up-front
Dwmapi.Preload(['DwmIsCompositionEnabled', 'DwmGetWindowAttribute', 'DwmSetWindowAttribute']);

// Check if DWM composition is enabled
const enabledBuf = Buffer.alloc(4);
Dwmapi.DwmIsCompositionEnabled(enabledBuf.ptr);
console.log('Composition enabled:', !!enabledBuf.readInt32LE(0));

// Get the system colorization color
const colorBuf = Buffer.alloc(4);
const opaqueBuf = Buffer.alloc(4);
Dwmapi.DwmGetColorizationColor(colorBuf.ptr, opaqueBuf.ptr);
console.log('Color:', '0x' + colorBuf.readUInt32LE(0).toString(16));

// Enable immersive dark mode on a window (requires a valid HWND)
// const darkMode = Buffer.alloc(4);
// darkMode.writeInt32LE(1, 0);
// Dwmapi.DwmSetWindowAttribute(hwnd, WindowAttribute.DWMWA_USE_IMMERSIVE_DARK_MODE, darkMode.ptr, 4);

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 example:

bun run example

Notes

• Either rely on lazy binding or call Dwmapi.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.