How to Call DLL Functions

The script engine can import procedures and functions from external DLL files, allowing you to extend your application by calling your own DLL functions.

How to Import a DLL Function in HEScript #

This is done with the external keyword.

Syntax:

function functionName(arguments): resultType;
[callingConvention]; external "libName.dll" [name 'ExternalFunctionName'];

For example, the following declaration:

function MyFunction(arg: integer): integer; external 'CustomLib.dll';

This imports a function called MyFunction from CustomLib.dll. The default calling convention is register if not otherwise specified.

HEScript allows you to declare a different calling convention (stdcall, register, pascal, cdecl, or safecall) and to use a different name for the DLL function, as in the following declaration:

function MsgBox(hWnd: Pointer; lpText, lpCaption: String;
uType: Cardinal): Integer; stdcall; external "user32.dll" name 'MessageBoxW';

This imports the MessageBoxW function from user32.dll (a Windows API library) and renames it to MsgBox for use in the script:

procedure TestDLL;
var
  S: String;
begin
  S := InputBox("What do you want to show?", "Query", "");
  MsgBox(0, S, "You entered:", MB_OK + MB_ICONINFORMATION);
end;

Other Examples #

The following Windows APIs can be imported into the HEScript engine with these declarations:

function GetDiskFreeSpace(root: AnsiString; var secPerCluster, bytesPerCluster, freeClusters, totalClusters: integer): boolean; stdcall; external "Kernel32.dll" name 'GetDiskFreeSpaceA';

function FindWindow(className, windowName: AnsiString): integer; stdcall; external "User32.dll" name 'FindWindowA';

function GetKeyState(virtKey: integer): smallint; stdcall; external "User32.dll";

Introduction to Scripting

Using the Script Manager

Script Function Reference