<窗体特效〉半透明窗体 像Foxmail3.1beta的一样

在windows2000下增加了一些API,可以轻易的实现半透明的窗体，源程序如下，必要的地方我加上了注释
unit Unit1;

interface

uses
  Windows, Messages, SysUtils, Classes, Graphics, Controls, Forms, Dialogs;

const
  WS_EX_LAYERED = $80000;
  AC_SRC_OVER = $0;
  AC_SRC_ALPHA = $1;
  AC_SRC_NO_PREMULT_ALPHA = $1;
  AC_SRC_NO_ALPHA = $2;
  AC_DST_NO_PREMULT_ALPHA = $10;
  AC_DST_NO_ALPHA = $20;
  LWA_COLORKEY = $1;
  LWA_ALPHA = $2;
  ULW_COLORKEY = $1
  ULW_ALPHA = $2
  ULW_OPAQUE = $4
//新增加的常量定义
type
  TForm1 = class(TForm)
    procedure FormCreate(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

function SetLayeredWindowAttributes(hwnd:HWND; crKey:Longint; bAlpha:byte; dwFlags:longint ):longint; stdcall; external user32;//函数声明

var
Form1: TForm1;

implementation
{$R *.DFM}
procedure TForm1.FormCreate(Sender: TObject);
var l:longint;
begin
    l:=getWindowLong(Handle, GWL_EXSTYLE);
    l := l Or WS_EX_LAYERED;
    SetWindowLong (handle, GWL_EXSTYLE, l);
    SetLayeredWindowAttributes (handle, 0, 180, LWA_ALPHA);
//第二个参数是指定透明颜色
//第二个参数为0则使用第四个参数设置alpha值，从0到255，其他的我不太清楚，因为没有api帮助
end;



end.

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