//unit UTransparent: Transparent the Windows;
unit UTransparent;

interface

uses Windows;

function TransparentWind(const Handle: THandle; Level: Byte; Toggle: Boolean): Boolean;
function LoadWin2k: Boolean;
function UnLoadWin2k: Boolean;
function WinVer: Integer;
function GetTrans(Int: Integer): Byte;

var
  TransLoaded: Boolean;

const
  OS_WINNT = 1; { WINDOWS NT}
  OS_WIN32 = 0; { WINDOWS 95 OR 98}
  OS_WINS = 2; { WIN32 UNDER WIN3.1}
  OS_WINNT4 = 3; { NT 4 }
  OS_WIN2k = 4; { Win2k - duh! }

implementation

var
  LayerFunc: Function(Handle: HWND; crKey: DWord; bAlpha: Byte; dwFlags: DWORD): Bool; stdcall;
  hDLL: HWND;

const
  WS_EX_LAYERED = $00080000;
  LWA_COLORKEY = $00000001;
  LWA_ALPHA = $00000002;
  ULW_COLORKEY = $00000001;
  ULW_ALPHA = $00000002;
  ULW_OPAQUE = $00000004;

function GetTrans(Int: Integer): Byte;
begin
  case Int of
    0: result := 0;
    1: result := 40;
    2: result := 80;
    3: result := 120;
    4: result := 160;
    5: result := 200;
    6: result := 240
  else
    result := 0;
  end;

end;

function WinVer: Integer;
var
  OSVerInfo: TOSVersionInfo;
begin
  try
    OSVerInfo.dwOSVersionInfoSize := SizeOf(TOSVersionInfo);
    GetVersionEx(OSVerInfo);
    result := OSVerInfo.dwMajorVersion;
    case OSVerInfo.dwPlatformID of
      VER_PLATFORM_WIN32s: Result := OS_WINS;
      VER_PLATFORM_WIN32_WINDOWS: result := OS_WIN32;
      VER_PLATFORM_WIN32_NT: begin
        case OSVerInfo.dwMajorVersion of
          1: result := OS_WINNT;
          2: result := OS_WINNT;
          3: result := OS_WINNT;
          4: result := OS_WINNT4;
          5: result := OS_WIN2k;
        end;
      end
    else
      result := OSVerInfo.dwPlatformID;
    end;
  except
    result := -1;
  end;
end;

function LoadTransDLL: Boolean;
begin
  try
    hDLL := LoadLibrary('user32.dll');
    if hDLL <> 0 then
      @LayerFunc := GetProcAddress(hDLL, 'SetLayeredWindowAttributes');
    result := true;
  except
    result := false;
  end;
end;

function LoadWin2k: Boolean;
begin
  if WinVer = OS_WIN2k then
  begin
    try
      if LoadTransDll then
      begin
        Result := True;
        TransLoaded := True;
      end
      else
      begin
        result := false;
        TransLoaded := false;
      end;
    except
      TransLoaded := false;
      result := false;
    end;
  end
  else
    result := false;
end;

function UnLoadWin2k: Boolean;
begin
  if WinVer = OS_WIN2k then
  begin
    try
      @LayerFunc := Nil;
      FreeLibrary(HDLL);
      result := true;
    except
      result := false;
    end;
  end
  else
    result := False;
end;

function TransparentWind(const Handle: THandle; Level: Byte; Toggle: Boolean): Boolean;
var
  dwLong,
  nAlpha: DWORD;
begin
  if WinVer = OS_WIN2k then
  begin
    if Toggle = true then
    begin // turn it on
      try
        if Level < 10 then Level := 10 // anything lower is blank
        else
          if Level > 240 then Level := 240; // anything higher is blank

        dwLong := GetWindowLong(Handle, GWL_EXSTYLE);
        nAlpha := Level;
        SetWindowLong(Handle, GWL_EXSTYLE, dwLong or WS_EX_LAYERED);
        LayerFunc(Handle, RGB(0,0,0), nAlpha, LWA_ALPHA);
        result := true;
      except
        result := false;
      end;
    end
    else
    begin // turn it off
      try
        dwLong := GetWindowLong(Handle, GWL_EXSTYLE);
        SetWindowLong(Handle, GWL_EXSTYLE, dwLong and (NOT WS_EX_LAYERED));
        result := true;
      except
        result := false;
      end;
    end;
    end

  else
    result := false; // oops- this isn't win2k
end;


end.