ShowContrastDlg example for C++ Builder

void __fastcall TForm1::ShowContrastDlg1Click(TObject *Sender) 
{
   L_INT nRet; 
   LEADDlgColor1->DlgFlags = DLG_CONTRAST_SHOW_PREVIEW |
                           DLG_CONTRAST_SHOW_TOOL_ZOOMLEVEL; 
   LEADDlgColor1->LEADImage = LEADImage1; 
   LEADDlgColor1->LEADDlgService = LEADDlgService1; 
   nRet= LEADDlgColor1->ShowContrastDlg ( this ); 
   if ( nRet == SUCCESS_DLG_OK ) 
   {
      LEADImage1->Contrast ( LEADDlgColor1->Change ); 
   }
}