bun-win32

Zero-dependency Win32 FFI bindings for Bun on Windows. Each system DLL is a standalone @bun-win32/* package with full type definitions.

Install

# Per-DLL packages:
bun add @bun-win32/kernel32 @bun-win32/user32 # etc...

# Or pull the entire surface in one install:
bun add @bun-win32/all     # scoped meta-package
bun add bun-win32          # unscoped alias for the same surface

Requires Bun >= 1.1.0 and Windows 10+.

Usage

After the first call resolves the symbol via dlopen/dlsym, the native function pointer is cached directly on the class. Every subsequent call is a straight pointer invocation through Bun's FFI - no marshaling layer, no runtime type checks, no wrapper overhead. It's the same codepath as calling the C function yourself.

For hot paths, Preload() resolves symbols eagerly so even the first call pays zero binding cost:

import Kernel32 from '@bun-win32/kernel32';

const pid = Kernel32.GetCurrentProcessId();
const ticks = Kernel32.GetTickCount64();

import User32 from '@bun-win32/user32';

User32.Preload(['GetForegroundWindow', 'SetWindowPos']);

const { GetForegroundWindow, SetWindowPos } = User32;

SetWindowPos(hWnd, 0n, x, y, width, height, flags);

[!IMPORTANT] If you destructure before binding, you capture the lazy wrapper instead of the native function.

Packages

All type definitions are provided by @bun-win32/core.

Published packages are AI-friendly. Alongside the README.md, each package includes an AI.md file that documents the binding contract, type surface, and source layout so coding agents can use the package correctly.

Graphics & Windowing

• comctl32 - common controls, image lists, property sheets, DPA/DSA dynamic arrays, flat scroll bars, window subclassing
• comdlg32 - common dialogs: Open / Save File, Choose Color, Choose Font, Print, Page Setup, Find / Replace, and CommDlgExtendedError
• d2d1 - Direct2D: GPU-accelerated 2D — ID2D1Factory / device-context creation plus Direct2D's native affine-matrix, color-space (sRGB / scRGB), gradient-mesh (Coons-patch), and trig / vector math (D2D1CreateFactory, D2D1MakeRotateMatrix, D2D1ConvertColorSpace, …)
• d3d11 - Direct3D 11 device / swap-chain creation, D3D11-on-12 interop, WinRT IDirect3DDevice / IDirect3DSurface bridges
• d3d12 - Direct3D 12 device creation, debug-layer / global-interface access, and root-signature serialize/deserialize (D3D12CreateDevice, D3D12GetDebugInterface, D3D12GetInterface, D3D12SerializeVersionedRootSignature, …) — modern GPU/compute/ML path
• d3dcompiler_47 - HLSL → DXBC shader compilation, preprocessing, disassembly, reflection, blob part extraction, shader stripping, function linking graph
• dcomp - DirectComposition device/surface creation (DCompositionCreateDevice/2/3, DCompositionCreateSurfaceHandle) and the Windows-11 compositor-clock frame/statistics surface (DCompositionGetFrameId, DCompositionGetStatistics, DCompositionWaitForCompositorClock, DCompositionBoostCompositorClock) — live compositor heartbeat proven pure-FFI
• dwmapi - DWM composition, blur, thumbnails
• dwrite - DirectWrite factory entry point (DWriteCreateFactory): system font enumeration, text layout, glyph metrics, and pure-FFI ClearType/grayscale glyph rasterization over the IDWriteFactory COM vtable
• dxcore - DXCore adapter-factory entry point (DXCoreCreateAdapterFactory): DXGI-independent GPU & compute-only MCDM adapter enumeration, hardware IDs, memory pools, and capability/attribute queries over the IDXCoreAdapterFactory/List/Adapter COM vtable
• dxgi - DXGI adapter enumeration, factory creation, debug interface (CreateDXGIFactory*, DXGIGetDebugInterface1)
• dxva2 - DDC/CI monitor configuration (brightness, contrast, RGB drive/gain, colour temperature, VCP), physical monitor enumeration, DXVA2 / DXVA-HD video acceleration, OPM video output
• gdi32 - graphics device interface
• gdiplus - GDI+ flat C API: image load/save (PNG, JPEG, BMP, GIF, TIFF, ICO), antialiased 2D drawing, paths, regions, gradients, brushes, fonts, color matrix effects, metafile recording
• glu32 - OpenGL utility functions
• magnification - Magnification API: recolor the entire desktop via a 5x5 color matrix (grayscale, photo-negative, sepia, color-blindness simulation), full-screen zoom/pan transforms, magnifier-control window filtering, and pen/touch input remapping
• mscms - Image Color Management (ICM): ICC profiles, color transforms, sRGB / Adobe RGB / CMYK conversion via Win32 CMM, display calibration, and the Windows Color System (WCS) profile management API
• opengl32 - OpenGL rendering context
• user32 - windows, messages, input, UI
• uxtheme - visual styles, themed controls, buffered painting
• windowscodecs - Windows Imaging Component (WIC): zero-build image decode/encode (JPEG, PNG, GIF, TIFF, BMP, HEIF), scaling, flip/rotate, pixel-format conversion, palettes, color contexts, and metadata — the full proxy-function surface

Multimedia

• avifil32 - Video for Windows AVIFile API: open/create .avi files, enumerate streams, read/write video, audio, MIDI, and text streams, decode frames to DIBs (AVIStreamGetFrame), mux files from streams, editable-stream cut/copy/paste
• avrt - MMCSS multimedia thread scheduling: join system-profile tasks ("Pro Audio", "Games", …), raise AVRT priority, query the system-responsiveness reservation, and coordinate thread-ordering groups (AvSetMmThreadCharacteristicsW, AvSetMmThreadPriority, AvQuerySystemResponsiveness, AvRtCreateThreadOrderingGroup) — the low-latency audio/capture scheduling primitives
• dinput8 - DirectInput 8: every non-Xbox controller — racing wheels, flight sticks / HOTAS, generic gamepads (DirectInput8Create, GetdfDIJoystick); device enumeration, capabilities, acquisition, and polling over the IDirectInput8 COM vtable
• directml - Vendor-neutral, Direct3D 12-backed machine-learning device creation (DMLCreateDevice, DMLCreateDevice1); creates a real IDMLDevice over an ID3D12Device and decodes its true max feature level over the IDMLDevice COM vtable — DirectML shipped, proven pure-FFI, audit 0 mismatches
• dsound - DirectSound: playback / capture device creation & enumeration, full-duplex, and default-device GUID resolution (DirectSoundCreate8, DirectSoundEnumerateW, GetDeviceID, …) — synthesize and play PCM end-to-end over the IDirectSound8 / IDirectSoundBuffer COM vtable
• gameinput - GameInput, the modern unified input model — GameInputCreate Nano-COM factory + Dll* COM-server entries; gamepad / keyboard / mouse / flight & arcade stick / racing wheel / sensor readings over the IGameInput COM vtable
• mf - Media Foundation pipeline: source resolver, ASF authoring graph (profile / multiplexer / indexer / splitter / stream selector), container media sinks (MP3 / AC-3 / ADTS / MPEG-4 / fragmented-MP4 / 3GP), streaming sinks, video renderer, network credential / proxy, and the protected-environment / signed-library surface (MFCreateSourceResolver, MFCreateASFProfile, MFCreateMPEG4MediaSink, MFGetSupportedSchemes, …)
• mfplat - Media Foundation platform: lifecycle, work queues, MFT registry, media type / sample / byte stream factories (MFStartup, MFTEnumEx, MFCreateAttributes, MFCreateSample)
• mfreadwrite - Media Foundation source reader / sink writer factories (MFCreateSourceReader*, MFCreateSinkWriter*)
• mmdevapi - MMDevice / Core Audio class factory, WASAPI async activation (DllGetClassObject, ActivateAudioInterfaceAsync)
• quartz - DirectShow runtime: HRESULT → text (AMGetErrorTextA/W) and the Filter Graph Manager Dll* COM server (CLSID_FilterGraph → IGraphBuilder); reaches legacy webcams / capture cards / codecs Media Foundation misses
• winmm - multimedia audio, MIDI, mixers, timers, joysticks, MCI
• xaudio2_9 - XAudio2 2.9: low-latency audio engine + voice graph, X3DAudio positional math (matrix / Doppler / LPF solve), and every built-in XAPO — volume meter, reverb, FXEQ / FXMasteringLimiter / FXReverb / FXEcho (XAudio2Create, X3DAudioInitialize, X3DAudioCalculate, CreateAudioVolumeMeter, CreateFX); synthesize and play PCM end-to-end over the IXAudio2 / IXAudio2SourceVoice COM vtable
• xinput1_4 - XInput 1.4: Xbox controller state, vibration, battery, audio, keystroke
• xinput9_1_0 - XInput 9.1.0: legacy Xbox controller state, vibration, DirectSound GUIDs

Networking