在QQ中，我可以调节面板的透明度。如果我们自己编程，应该如何实现呢？     （一）半透明窗体      在windows2000以及后续产品中下增加了一些API,可以轻易的实现半透明的窗体，源程序如下： interface uses   Windows, Messages, SysUtils, Classes, Graphics, Controls, Forms, Dialogs; const//定义常量   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 = $4 type   TForm1 = class(TForm)   procedure FormCreate(Sender: TObject);   private   { Private declarations }   public   { Public declarations }   end; function SetLayeredWindowAttributes(hwnd:HWND; crKey:Longint; bAlpha:byte; dwFlags:longint ):longint; stdcall; external user32;//函数声明 var Form1: TForm1; implementation {$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 end; end.      （二） 透明窗体的实现       将一个FORM变成透明的实质性手段就是拦截CMEraseBkgnd消息。 unit Utransform; interface uses Windows, Messages, SysUtils, Classes, Graphics, Controls, Forms, Dialogs, StdCtrls, ExtCtrls; type TForm1 = class(TForm)     private { Private declarations }     public { Public declarations }        PROCEDURE CMEraseBkgnd(var Message:TWMEraseBkgnd);Message WM_ERASEBKGND; end; var Form1: TForm1; implementation {$R *.DFM} procedure TForm1.CMEraseBkgnd(var Message: TWMEraseBkgnd);beginbrush.style:=bsClear;end; procedure TForm1.FormCreate(Sender: TObject);begin  Form1.Brush.Style := bsClear;//如果只拦截消息，没有这里的设置，窗内的标题栏一样会显示    Form1.BorderStyle := bsNoneend; procedure TForm1.BitBtn1Click(Sender: TObject);begin  close;end;

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