; -- CodeDll.iss --
;
; This script shows how to call functions in external DLLs (like Windows API functions)
; at runtime and how to perform direct callbacks from these functions to functions
; in the script.

[Setup]
AppName=My Program
AppVersion=1.5
WizardStyle=modern
DefaultDirName={autopf}\My Program
DisableProgramGroupPage=yes
DisableWelcomePage=no
UninstallDisplayIcon={app}\MyProg.exe
OutputDir=userdocs:Inno Setup Examples Output

[Files]
Source: "MyProg.exe"; DestDir: "{app}"
Source: "MyProg.chm"; DestDir: "{app}"
Source: "Readme.txt"; DestDir: "{app}"; Flags: isreadme
; Install our DLL to {app} so we can access it at uninstall time.
; Use "Flags: dontcopy" if you don't need uninstall time access.
Source: "MyDll.dll"; DestDir: "{app}"

[Code]
const
  MB_ICONINFORMATION = $40;

// Importing a Unicode Windows API function.
function MessageBox(hWnd: Integer; lpText, lpCaption: String; uType: Cardinal): Integer;
external 'MessageBoxW@user32.dll stdcall';

// Importing an ANSI custom DLL function, first for Setup, then for uninstall.
procedure MyDllFuncSetup(hWnd: Integer; lpText, lpCaption: AnsiString; uType: Cardinal);
external 'MyDllFunc@files:MyDll.dll stdcall setuponly';

procedure MyDllFuncUninstall(hWnd: Integer; lpText, lpCaption: AnsiString; uType: Cardinal);
external 'MyDllFunc@{app}\MyDll.dll stdcall uninstallonly';

// Importing an ANSI function for a DLL which might not exist at runtime.
procedure DelayLoadedFunc(hWnd: Integer; lpText, lpCaption: AnsiString; uType: Cardinal);
external 'DllFunc@DllWhichMightNotExist.dll stdcall delayload';

function NextButtonClick(CurPage: Integer): Boolean;
var
  hWnd: Integer;
begin
  if CurPage = wpWelcome then begin
    hWnd := StrToInt(ExpandConstant('{wizardhwnd}'));

    MessageBox(hWnd, 'Hello from Windows API function', 'MessageBoxA', MB_OK or MB_ICONINFORMATION);

    MyDllFuncSetup(hWnd, 'Hello from custom DLL function', 'MyDllFunc', MB_OK or MB_ICONINFORMATION);

    try
      // If this DLL does not exist (it shouldn't), an exception will be raised. Press F9 to continue.
      DelayLoadedFunc(hWnd, 'Hello from delay loaded function', 'DllFunc', MB_OK or MB_ICONINFORMATION);
    except
      // <Handle missing dll here>
    end;
  end;
  Result := True;
end;

procedure CurUninstallStepChanged(CurUninstallStep: TUninstallStep);
begin
  // Call our function just before the actual uninstall process begins.
  if CurUninstallStep = usUninstall then begin
    MyDllFuncUninstall(0, 'Hello from custom DLL function', 'MyDllFunc', MB_OK or MB_ICONINFORMATION);
    
    // Now that we're finished with it, unload MyDll.dll from memory.
    // We have to do this so that the uninstaller will be able to remove the DLL and the {app} directory.
    UnloadDLL(ExpandConstant('{app}\MyDll.dll'));
  end;
end;

// The following shows how to use callbacks.

function SetTimer(hWnd, nIDEvent, uElapse, lpTimerFunc: Longword): Longword;
external 'SetTimer@user32.dll stdcall';

var
  TimerCount: Integer;

procedure MyTimerProc(Arg1, Arg2, Arg3, Arg4: Longword);
begin
  Inc(TimerCount);
  WizardForm.BeveledLabel.Caption := ' Timer! ' + IntToStr(TimerCount) + ' ';
  WizardForm.BeveledLabel.Visible := True;
end;

procedure InitializeWizard;
begin
  SetTimer(0, 0, 1000, CreateCallback(@MyTimerProc));
end;