bclayeredwindows.pas

BarMenus230.zip

{ Unit: BcLayeredWindows
  ===========================================================================
  Created: 2001-07-29 (yyyy-mm-dd)
  ===========================================================================

  The contents of this file are subject to the Bluecave Public License V 1.1
  (the "License"). You may not copy or use this file, in either source code
  or executable form, except in compliance with the License. You may obtain
  a copy of the License at http://www.bluecave.net/licenses/.

  Software distributed under the License is distributed on an "AS IS" basis,
  WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
  for the specific language governing rights and limitations under the
  License.

  Copyright (C) 2001 Bluecave Software. All Rights Reserved.
  http://www.bluecave.net/

  Copyright (C) 2001 Jouni Airaksinen. All Rights Reserved.
  http://Mintus.Codefield.com/ -- [e-mail]

  ===========================================================================

  Unit description:

    Needed definitions for Layered Windows API.

    Notes: This is not complete api as it has been made for BarMenu Components.
      It might be expanded later. API is loaded dynamically, so be sure
      to check the SupportsLayeredWindows global to determine if LayeredWindows
      API is available.

  History:

    2001-10-11: Added UpdateLayeredWindow
    2001-07-29: Initial version.

  =========================================================================== }

{$I DFS.inc}
{$I BcDirectives.inc}

unit BcLayeredWindows;

interface

{$IFDEF MSWINDOWS}

uses Windows;

const
  LWA_ALPHA = $00000002;
  WS_EX_LAYERED = $00080000;


function SupportsLayeredWindows: Boolean;

type
  TSetLayeredWindowAttributes = function(hWnd: THandle; crKey: TColorRef; bAlpha: Byte;
    dwFlags: Cardinal): BOOL; stdcall;
  TUpdateLayeredWindow = function(hWnd: THandle; hdcDst: HDC; pptDst: PPoint;
    psize: PSize; hdcSrc: HDC; pptSrc: PPoint; crKey: TColorRef;
    var blend: TBlendFunction; dwFlags: Cardinal): BOOL; stdcall;

var
  UpdateLayeredWindow: TUpdateLayeredWindow = nil;
  SetLayeredWindowAttributes: TSetLayeredWindowAttributes = nil;
{$ENDIF}

implementation

{$IFDEF MSWINDOWS}
var
  User32Dll: HMODULE;
  FSupportsLayeredWindows: Boolean;

function SupportsLayeredWindows: Boolean;
begin
  Result := FSupportsLayeredWindows;
end;

initialization
  User32Dll := LoadLibrary(user32);
  FSupportsLayeredWindows := False;
  if User32Dll <> 0 then
  begin
    UpdateLayeredWindow := GetProcAddress(User32Dll, 'UpdateLayeredWindow');
    SetLayeredWindowAttributes := GetProcAddress(User32Dll, 'SetLayeredWindowAttributes');
    FreeLibrary(User32Dll);

    FSupportsLayeredWindows := Assigned(SetLayeredWindowAttributes);
  end;

finalization
{$ENDIF}

end.