Windows DLL & COM Reference

All native Windows API calls are made via syscall.SyscallN and windows.NewLazySystemDLL — no CGo, no .c/.h files. CGo is used only indirectly via the Zig cc build toolchain for ONNX runtime linking. The Go-native transformer engine (ml/ module, action prediction) is pure Go via Gorgonia — no CGO or DLL dependencies.

System DLLs

user32.dll

| File | Procs Used | Purpose | |——|———–|———| | user32.go | GetDC, ReleaseDC, GetSystemMetrics, GetWindowDC, GetDesktopWindow, WindowFromPoint, GetUpdateRect, GetWindowRect, SetWindowPos, ShowWindow, EnumWindows, GetWindowTextW, GetWindowTextLengthW, IsWindowVisible, GetForegroundWindow, SetForegroundWindow, AttachThreadInput, GetWindowThreadProcessId, GetCurrentThreadId, GetMenuItemCount, GetMenuItemRect, ClientToScreen | Core window management, focus, enumeration | | keyboard.go | SendInput | Input simulation via INPUT struct | | mouse.go | SendInput, GetCursorPos | Mouse simulation | | keylogger.go | SetWinEventHook, UnhookWinEvent, GetMessageW, GetAsyncKeyState, GetKeyState, VkKeyScanW, MapVirtualKeyW, ToUnicode, GetKeyboardState, GetKeyboardLayout, GetForegroundWindow | WinEvent hook for input recording | | uia_com.go | via IUIAutomation COM interface | Accessibility tree navigation | | layout.go | GetKeyboardLayout, GetKeyboardLayoutNameW, ActivateKeyboardLayout, LoadKeyboardLayoutW | Keyboard layout enumeration/switching | | window.go | EnumWindows, FindWindowW, SetForegroundWindow, MoveWindow, ShowWindowAsync, GetWindowRect, IsIconic, IsZoomed, GetWindowTextW, GetWindowThreadProcessId, AttachThreadInput | Window enumeration, focus, state | | window_ext.go | MoveWindow, GetWindowRect, ShowWindowAsync, PostMessageW, IsIconic, IsZoomed, FindWindowW, MonitorFromWindow | Extended window ops, fullscreen detection |

gdi32.dll

| File | Procs Used | Purpose | |——|———–|———| | screenshot.go | CreateCompatibleDC, CreateCompatibleBitmap, SelectObject, BitBlt, GetDIBits, DeleteDC, DeleteObject, CreateDCW | GDI screen capture, bitmap conversion | | dpi.go | GetDeviceCaps | LOGPIXELSX/Y for DPI |

kernel32.dll

| File | Procs Used | Purpose | |——|———–|———| | system.go | GetComputerNameW, GetNativeSystemInfo, GlobalMemoryStatusEx | System info | | process.go | CreateToolhelp32Snapshot, Process32First, Process32Next, OpenProcess, TerminateProcess, CloseHandle | Process listing/management | | window.go | OpenProcess, GetModuleBaseNameW, GetWindowThreadProcessId | Process-per-window | | idle.go | GetLastInputInfo | Idle time | | power.go | GetDiskFreeSpaceW | Disk usage | | audio.go | GetVolumeInformationW | Volume info |

shell32.dll

| File | Procs Used | Purpose | |——|———–|———| | system.go | ShellExecuteW | Open URLs, launch files | | windowexploreruse.go | ShellExecuteW | File Explorer automation |

shcore.dll

| File | Procs Used | Purpose | |——|———–|———| | dpi.go | SetProcessDpiAwareness, GetDpiForMonitor, GetScaleFactorForMonitor | DPI awareness, per-monitor scaling |

ntdll.dll

| File | Procs Used | Purpose | |——|———–|———| | misc.go | NtQuerySystemInformation | System power status | | system.go | RtlGetVersion | OS version details |

powrprof.dll

| File | Procs Used | Purpose | |——|———–|———| | power.go | SetSuspendState, GetPwrCapabilities | Sleep, hibernate |

advapi32.dll

| File | Procs Used | Purpose | |——|———–|———| | uipi.go | OpenProcessToken, GetTokenInformation | UIPI elevation detection via TOKEN_ELEVATION (see uipi.md for full logic) |

iphlpapi.dll

| File | Procs Used | Purpose | |——|———–|———| | network.go | GetNetworkParams, GetAdaptersInfo | Network info |

winmm.dll

| File | Procs Used | Purpose | |——|———–|———| | system.go | waveOutGetVolume, waveOutSetVolume | System audio volume |

COM & WinRT Infrastructure

ole32.dll / oleaut32.dll

| File | Functions Used | Purpose | |——|—————|———| | uia_com.go | CoInitializeEx, CoCreateInstance, CoTaskMemFree, SysFreeString, VariantClear | UIA COM initialization, BSTR/VARIANT management |

combase.dll

| File | Functions Used | Purpose | |——|—————|———| | winrt.go | RoInitialize, RoGetActivationFactory, WindowsCreateStringReference, WindowsDeleteString, WindowsGetStringRawBuffer | WinRT COM infrastructure | | ocr_com.go | RoInitialize, RoGetActivationFactory, WindowsCreateString, WindowsDeleteString, WindowsGetStringRawBuffer | WinRT OCR via Windows.Media.Ocr.OcrEngine | | ocr.go | RoGetActivationFactory, WindowsCreateString, WindowsDeleteString, vtbl method calls on IOcrEngineStatics | OcrLanguages() enumeration |

onnxruntime.dll

| File | Purpose | |——|———| | onnx.go | Loaded at runtime via onnxruntime_go Go library. YOLO detection + MobileNet classifier inference. Downloaded by onnx_download tool from https://github.com/microsoft/onnxruntime/releases |

COM Interface Architecture

WinRT (combase.dll)
  ├── Windows.Media.Ocr.OcrEngine — OCR (ocr_com.go)
  │     └── IOcrEngineStatics → OcrEngine → OcrResult → OcrLine[] → OcrWord[]
  ├── Windows.Storage.StorageFile — file access for OCR images
  └── Windows.Graphics.Imaging — bitmap decode for OCR

UIA (ole32.dll → IUIAutomation)
  └── UIA COM vtbl interface (uia_com.go)
        ├── IUIAutomation → CreateTrueCondition, CreatePropertyCondition
        ├── IUIAutomationElement → GetCurrentPropertyValue, GetCurrentPattern
        └── IUIAutomationCondition → tree traversal

SendInput (user32.dll — kernel-mode input injection)
  ├── keyboard.go: KEYEVENTF_UNICODE + virtual key codes
  └── mouse.go: MOUSEEVENTF_LEFTDOWN/UP, RIGHT, MIDDLE, WHEEL, HWHEEL

Calling Convention

All DLL calls use the same pattern:

var user32 = windows.NewLazySystemDLL("user32.dll")
var findWindowW = user32.NewProc("FindWindowW")

func FindWindow(title string) uintptr {
    ptr, _ := syscall.UTF16PtrFromString(title)
    hwnd, _, _ := findWindowW.Call(0, uintptr(unsafe.Pointer(ptr)))
    return hwnd
}

COM vtbl calls use syscall.SyscallN with method index on the vtable:

func vtblMethod(unk unsafe.Pointer, idx int) uintptr {
    return *(*uintptr)(unsafe.Pointer(
        *(*uintptr)(unk) + uintptr(idx)*unsafe.Sizeof(uintptr(0)),
    ))
}

Cross-Reference

• docs/reference/codebase-map.md — tool→handler→action→file mapping
• docs/reference/com-patterns.md — COM threading, vtable dispatch, async polling, HSTRING/BSTR lifecycle
• docs/guides/build.md — Zig cc build, CGO linking
• docs/reference/models-setup.md — ONNX model download