怎样使窗体透明呢？

Question

procedure WMEraseBkGnd(var Msg: TWMEraseBkGnd); message WM_ERASEBKGND;procedure TForm2.WMEraseBkGnd(var Msg: TWMEraseBkGnd);
begin
    Msg.Result := 1 ;
end;

Answer 1

type
  TSetLayeredWindowAttributes = function (hwnd:HWND; crKey:Longint; bAlpha:byte; dwFlags:longint ):longint; stdcall;var
  Form1: TForm1;
  SetLayeredWindowAttributes: TSetLayeredWindowAttributes = nil;...procedure InitProcs;
const
  sUser32 = 'User32.dll';
var
  ModH: HMODULE;
begin
  ModH := GetModuleHandle(sUser32);
  if ModH <> 0 then
    @SetLayeredWindowAttributes := GetProcAddress(ModH, 'SetLayeredWindowAttributes');
end;procedure TForm1.FormCreate(Sender: TObject);
var AStyle:Integer;
begin
  InitProcs;
  Alpha:=150;//0为完全透明，255完全不透明
  AStyle := GetWindowLong(Handle, GWL_EXSTYLE);
  if (AStyle and $00080000) = 0 then
    SetWindowLong(Handle, GWL_EXSTYLE, AStyle or $00080000);
  if assigned(SetLayeredWindowAttributes) then
    SetLayeredWindowAttributes(Handle,0,Alpha,$2);
end;

Answer 2

老大,你这里编译不过去呀!' Alpha:=150.
还没有定义变量呢!