@bun-win32/shcore

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

Overview

@bun-win32/shcore exposes the shcore.dll exports using Bun's FFI. It provides a single class, Shcore, 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 shcore.dll (DPI awareness, scale factors, AppUserModelID, random access streams, registry helpers, and more).
• In-source docs in structs/Shcore.ts with links to Microsoft Docs.
• Lazy binding on first call; optional eager preload (Shcore.Preload()).
• No wrapper overhead; calls map 1:1 to native APIs.
• Strongly-typed Win32 aliases (see types/Shcore.ts).

Requirements

• Bun runtime
• Windows 10 or later

Installation

bun add @bun-win32/shcore

Quick Start

import Shcore, { ProcessDpiAwareness } from '@bun-win32/shcore';

// Optionally bind a subset up-front
Shcore.Preload(['SetProcessDpiAwareness', 'GetScaleFactorForDevice']);

// Opt in to per-monitor DPI awareness (0 on success)
const hr = Shcore.SetProcessDpiAwareness(ProcessDpiAwareness.PROCESS_PER_MONITOR_DPI_AWARE);
console.log('SetProcessDpiAwareness hr: 0x%s', (hr >>> 0).toString(16));

// Read the preferred scale factor for the primary display (DEVICE_PRIMARY = 0)
const scale = Shcore.GetScaleFactorForDevice(0);
console.log('Primary display scale: %d%%', scale);

[!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:dpi-scope     # Visualize DPI, scale, and shell UI sizing
bun run example:shcore        # Process DPI awareness + AppUserModelID roundtrip

Notes

• Either rely on lazy binding or call Shcore.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.