주어진 폼을 프린트 하는 기능을 여러 군데서 짜집기를 해서 만들었습니다.
가장큰 차이점은 GetFormImage() 함수를 사용하지 않은 점입니다.
간혹 무한루프를 타서요...

void __fastcall TFormMain::ButtonPrintClick(TObject *Sender)
{
//
    TForm * pForm = FormMain;    // Set Printing Form

    Graphics::TBitmap *mjbmp = new Graphics::TBitmap();
    mjbmp->Width = pForm->ClientWidth;
    mjbmp->Height = pForm->ClientHeight;
    mjbmp->Canvas->CopyRect ( Rect(0, 0,mjbmp->Width, mjbmp->Height),
        pForm->Canvas, Rect(0, 0, pForm->ClientWidth, pForm->ClientHeight));

    if (!PrintDialog1->Execute()) return;
    //Graphics::TBitmap *mjbmp= FormMain->GetFormImage();
    TPrinter *prt=Printer();
    mjbmp->HandleType=bmDIB; // This is *VERY* important
    double h=mjbmp->Height,w=mjbmp->Width,fct,wf;
    if (w>h) prt->Orientation=poLandscape;
    else prt->Orientation=poPortrait;

    prt->Title="SPINDLE TEST PRINT";
    wf=(double)prt->PageWidth/w;
    fct=(double)prt->PageHeight/h;
    if (fct>wf) fct=wf;

    prt->BeginDoc();
    prt->Canvas->StretchDraw(Rect(0,0,fct*w-1,fct*h-1),mjbmp);
    prt->Canvas->TextOut(0,0,"PRINT OK");
    prt->EndDoc();
    delete mjbmp;
}