GetSystemMetricsForDpi

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

INT GetSystemMetricsForDpi(
    SYSTEM_METRICS_INDEX nIndex,
    DWORD dpi
);

<DllImport("USER32.dll", SetLastError:=True, ExactSpelling:=True)>
Public Shared Function GetSystemMetricsForDpi(
    nIndex As Integer,   ' SYSTEM_METRICS_INDEX
    dpi As UInteger   ' DWORD
) As Integer
End Function

' nIndex : SYSTEM_METRICS_INDEX
' dpi : DWORD
Declare PtrSafe Function GetSystemMetricsForDpi Lib "user32" ( _
    ByVal nIndex As Long, _
    ByVal dpi As Long) As Long
' VBA7前提(PtrSafe)。32bit Office では LongPtr→Long。Integer=16bit / Long=32bit / LongLong=64bit。

import ctypes
from ctypes import wintypes

GetSystemMetricsForDpi = ctypes.windll.user32.GetSystemMetricsForDpi
GetSystemMetricsForDpi.restype = ctypes.c_int
GetSystemMetricsForDpi.argtypes = [
    ctypes.c_int,  # nIndex : SYSTEM_METRICS_INDEX
    wintypes.DWORD,  # dpi : DWORD
]
# GetLastError: use ctypes.GetLastError() (or ctypes.WinDLL(use_last_error=True))

require 'fiddle'
require 'fiddle/import'

lib = Fiddle.dlopen('USER32.dll')
GetSystemMetricsForDpi = Fiddle::Function.new(
  lib['GetSystemMetricsForDpi'],
  [
    Fiddle::TYPE_INT,  # nIndex : SYSTEM_METRICS_INDEX
    -Fiddle::TYPE_INT,  # dpi : DWORD
  ],
  Fiddle::TYPE_INT)

#[link(name = "user32")]
extern "system" {
    fn GetSystemMetricsForDpi(
        nIndex: i32,  // SYSTEM_METRICS_INDEX
        dpi: u32  // DWORD
    ) -> i32;
}
// crates: windows-sys provides ready-made bindings for this API.

$sig = @"
[DllImport("USER32.dll", SetLastError = true)]
public static extern int GetSystemMetricsForDpi(int nIndex, uint dpi);
"@
$api = Add-Type -MemberDefinition $sig -Name 'USER32_GetSystemMetricsForDpi' -Namespace Win32 -PassThru
# $api::GetSystemMetricsForDpi(nIndex, dpi)

#uselib "USER32.dll"
#func global GetSystemMetricsForDpi "GetSystemMetricsForDpi" sptr, sptr
; GetSystemMetricsForDpi nIndex, dpi   ; 戻り値は stat
; nIndex : SYSTEM_METRICS_INDEX -> "sptr"
; dpi : DWORD -> "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 GetSystemMetricsForDpi "GetSystemMetricsForDpi" int, int
; res = GetSystemMetricsForDpi(nIndex, dpi)
; nIndex : SYSTEM_METRICS_INDEX -> "int"
; dpi : DWORD -> "int"

; INT GetSystemMetricsForDpi(SYSTEM_METRICS_INDEX nIndex, DWORD dpi)
#uselib "USER32.dll"
#cfunc global GetSystemMetricsForDpi "GetSystemMetricsForDpi" int, int
; res = GetSystemMetricsForDpi(nIndex, dpi)
; nIndex : SYSTEM_METRICS_INDEX -> "int"
; dpi : DWORD -> "int"

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

var (
	user32 = windows.NewLazySystemDLL("USER32.dll")
	procGetSystemMetricsForDpi = user32.NewProc("GetSystemMetricsForDpi")
)

// nIndex (SYSTEM_METRICS_INDEX), dpi (DWORD)
r1, _, err := procGetSystemMetricsForDpi.Call(
	uintptr(nIndex),
	uintptr(dpi),
)
_ = err  // syscall.Errno (valid when the call sets last-error)
_ = r1   // INT

function GetSystemMetricsForDpi(
  nIndex: Integer;   // SYSTEM_METRICS_INDEX
  dpi: DWORD   // DWORD
): Integer; stdcall;
  external 'USER32.dll' name 'GetSystemMetricsForDpi';

result := DllCall("USER32\GetSystemMetricsForDpi"
    , "Int", nIndex   ; SYSTEM_METRICS_INDEX
    , "UInt", dpi   ; DWORD
    , "Int")   ; return: INT

●GetSystemMetricsForDpi(nIndex, dpi) = DLL("USER32.dll", "int GetSystemMetricsForDpi(int, dword)")
# 呼び出し: GetSystemMetricsForDpi(nIndex, dpi)
# nIndex : SYSTEM_METRICS_INDEX -> "int"
# dpi : DWORD -> "dword"
# 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)。