GetLayeredWindowAttributes

// USER32.dll
#include <windows.h>

BOOL GetLayeredWindowAttributes(
    HWND hwnd,
    COLORREF* pcrKey,   // optional
    BYTE* pbAlpha,   // optional
    LAYERED_WINDOW_ATTRIBUTES_FLAGS* pdwFlags   // optional
);

<DllImport("USER32.dll", SetLastError:=True, ExactSpelling:=True)>
Public Shared Function GetLayeredWindowAttributes(
    hwnd As IntPtr,   ' HWND
    pcrKey As IntPtr,   ' COLORREF* optional, out
    pbAlpha As IntPtr,   ' BYTE* optional, out
    pdwFlags As IntPtr   ' LAYERED_WINDOW_ATTRIBUTES_FLAGS* optional, out
) As Boolean
End Function

' hwnd : HWND
' pcrKey : COLORREF* optional, out
' pbAlpha : BYTE* optional, out
' pdwFlags : LAYERED_WINDOW_ATTRIBUTES_FLAGS* optional, out
Declare PtrSafe Function GetLayeredWindowAttributes Lib "user32" ( _
    ByVal hwnd As LongPtr, _
    ByVal pcrKey As LongPtr, _
    ByVal pbAlpha As LongPtr, _
    ByVal pdwFlags As LongPtr) As Long
' VBA7前提(PtrSafe)。32bit Office では LongPtr→Long。Integer=16bit / Long=32bit / LongLong=64bit。

import ctypes
from ctypes import wintypes

GetLayeredWindowAttributes = ctypes.windll.user32.GetLayeredWindowAttributes
GetLayeredWindowAttributes.restype = wintypes.BOOL
GetLayeredWindowAttributes.argtypes = [
    wintypes.HANDLE,  # hwnd : HWND
    ctypes.c_void_p,  # pcrKey : COLORREF* optional, out
    ctypes.POINTER(ctypes.c_ubyte),  # pbAlpha : BYTE* optional, out
    ctypes.c_void_p,  # pdwFlags : LAYERED_WINDOW_ATTRIBUTES_FLAGS* optional, out
]
# GetLastError: use ctypes.GetLastError() (or ctypes.WinDLL(use_last_error=True))

require 'fiddle'
require 'fiddle/import'

lib = Fiddle.dlopen('USER32.dll')
GetLayeredWindowAttributes = Fiddle::Function.new(
  lib['GetLayeredWindowAttributes'],
  [
    Fiddle::TYPE_VOIDP,  # hwnd : HWND
    Fiddle::TYPE_VOIDP,  # pcrKey : COLORREF* optional, out
    Fiddle::TYPE_VOIDP,  # pbAlpha : BYTE* optional, out
    Fiddle::TYPE_VOIDP,  # pdwFlags : LAYERED_WINDOW_ATTRIBUTES_FLAGS* optional, out
  ],
  Fiddle::TYPE_INT)

#[link(name = "user32")]
extern "system" {
    fn GetLayeredWindowAttributes(
        hwnd: *mut core::ffi::c_void,  // HWND
        pcrKey: *mut u32,  // COLORREF* optional, out
        pbAlpha: *mut u8,  // BYTE* optional, out
        pdwFlags: *mut u32  // LAYERED_WINDOW_ATTRIBUTES_FLAGS* optional, out
    ) -> i32;
}
// crates: windows-sys provides ready-made bindings for this API.

$sig = @"
[return: MarshalAs(UnmanagedType.Bool)]
[DllImport("USER32.dll", SetLastError = true)]
public static extern bool GetLayeredWindowAttributes(IntPtr hwnd, IntPtr pcrKey, IntPtr pbAlpha, IntPtr pdwFlags);
"@
$api = Add-Type -MemberDefinition $sig -Name 'USER32_GetLayeredWindowAttributes' -Namespace Win32 -PassThru
# $api::GetLayeredWindowAttributes(hwnd, pcrKey, pbAlpha, pdwFlags)

#uselib "USER32.dll"
#func global GetLayeredWindowAttributes "GetLayeredWindowAttributes" sptr, sptr, sptr, sptr
; GetLayeredWindowAttributes hwnd, pcrKey, varptr(pbAlpha), pdwFlags   ; 戻り値は stat
; hwnd : HWND -> "sptr"
; pcrKey : COLORREF* optional, out -> "sptr"
; pbAlpha : BYTE* optional, out -> "sptr"
; pdwFlags : LAYERED_WINDOW_ATTRIBUTES_FLAGS* optional, out -> "sptr"
; ※HSP3.7は #func のため戻り値はシステム変数 stat に格納されます。

#uselib "USER32.dll"
#cfunc global GetLayeredWindowAttributes "GetLayeredWindowAttributes" sptr, int, var, int
; res = GetLayeredWindowAttributes(hwnd, pcrKey, pbAlpha, pdwFlags)
; hwnd : HWND -> "sptr"
; pcrKey : COLORREF* optional, out -> "int"
; pbAlpha : BYTE* optional, out -> "var"
; pdwFlags : LAYERED_WINDOW_ATTRIBUTES_FLAGS* optional, out -> "int"
; ※出力/バッファ引数は var 方式(変数を直接渡す)。varptr 方式にも切替可。

; BOOL GetLayeredWindowAttributes(HWND hwnd, COLORREF* pcrKey, BYTE* pbAlpha, LAYERED_WINDOW_ATTRIBUTES_FLAGS* pdwFlags)
#uselib "USER32.dll"
#cfunc global GetLayeredWindowAttributes "GetLayeredWindowAttributes" intptr, int, var, int
; res = GetLayeredWindowAttributes(hwnd, pcrKey, pbAlpha, pdwFlags)
; hwnd : HWND -> "intptr"
; pcrKey : COLORREF* optional, out -> "int"
; pbAlpha : BYTE* optional, out -> "var"
; pdwFlags : LAYERED_WINDOW_ATTRIBUTES_FLAGS* optional, out -> "int"
; ※出力/バッファ引数は var 方式(変数を直接渡す)。varptr 方式にも切替可。

import (
	"golang.org/x/sys/windows"
	"unsafe"
)

var (
	user32 = windows.NewLazySystemDLL("USER32.dll")
	procGetLayeredWindowAttributes = user32.NewProc("GetLayeredWindowAttributes")
)

// hwnd (HWND), pcrKey (COLORREF* optional, out), pbAlpha (BYTE* optional, out), pdwFlags (LAYERED_WINDOW_ATTRIBUTES_FLAGS* optional, out)
r1, _, err := procGetLayeredWindowAttributes.Call(
	uintptr(hwnd),
	uintptr(pcrKey),
	uintptr(pbAlpha),
	uintptr(pdwFlags),
)
_ = err  // syscall.Errno (valid when the call sets last-error)
_ = r1   // BOOL

function GetLayeredWindowAttributes(
  hwnd: THandle;   // HWND
  pcrKey: Pointer;   // COLORREF* optional, out
  pbAlpha: Pointer;   // BYTE* optional, out
  pdwFlags: Pointer   // LAYERED_WINDOW_ATTRIBUTES_FLAGS* optional, out
): BOOL; stdcall;
  external 'USER32.dll' name 'GetLayeredWindowAttributes';

result := DllCall("USER32\GetLayeredWindowAttributes"
    , "Ptr", hwnd   ; HWND
    , "Ptr", pcrKey   ; COLORREF* optional, out
    , "Ptr", pbAlpha   ; BYTE* optional, out
    , "Ptr", pdwFlags   ; LAYERED_WINDOW_ATTRIBUTES_FLAGS* optional, out
    , "Int")   ; return: BOOL

●GetLayeredWindowAttributes(hwnd, pcrKey, pbAlpha, pdwFlags) = DLL("USER32.dll", "bool GetLayeredWindowAttributes(void*, void*, void*, void*)")
# 呼び出し: GetLayeredWindowAttributes(hwnd, pcrKey, pbAlpha, pdwFlags)
# hwnd : HWND -> "void*"
# pcrKey : COLORREF* optional, out -> "void*"
# pbAlpha : BYTE* optional, out -> "void*"
# pdwFlags : LAYERED_WINDOW_ATTRIBUTES_FLAGS* optional, out -> "void*"
# なでしこ1は32bit・ANSI(Shift_JIS)。文字列=char*(ANSI)、ポインタ/ハンドル=void*(4byte)。