Прозрачность формы

Code:

unit TransparentWnd;

interface

uses

Windows, Messages, Classes, Controls, Forms;

type

_Percentage = 0..100;

TTransparentWnd = class(TComponent)

private

   { Private declarations }

protected

   { Protected declarations }

   _percent: _Percentage;

   _auto: boolean;

   User32: HMODULE;

public

   { Public declarations }

   constructor Create(AOwner: TComponent); override;

   destructor Destroy; override;

   //These work on a Handle

   //It doesn't change the Percent Property Value!

   procedure SetTransparentHWND(hwnd: THandle; percent : _Percentage);

   //These work on the Owner (a TWinControl decendant is the Minumum)

   //They don't change the Percent Property Value!

   procedure SetTransparent; overload;

   procedure SetTransparent(percent : _Percentage); overload;

   procedure SetOpaqueHWND(hwnd : THandle);

   procedure SetOpaque;

published

   { Published declarations }

   //This works on the Owner (a TWinControl decendant is the Minumum)

   property Percent: _Percentage read _percent write _percent default 0;

   property AutoOpaque: boolean read _auto write _auto default false;

end;

procedure register;

implementation

const LWA_ALPHA = $2;

const GWL_EXSTYLE = (-20);

const WS_EX_LAYERED = $80000;

const WS_EX_TRANSPARENT = $20;

var

SetLayeredWindowAttributes: function (hwnd: LongInt; crKey: byte;

   bAlpha: byte; dwFlags: LongInt): LongInt; stdcall;

constructor TTransparentWnd.Create(AOwner: TComponent);

begin

inherited;

User32 := LoadLibrary('USER32.DLL');

if User32 <> 0 then

   @SetLayeredWindowAttributes := GetProcAddress(User32, 'SetLayeredWindowAttributes')

else

   SetLayeredWindowAttributes := nil;

end;

destructor TTransparentWnd.Destroy;

begin

if User32 <> 0 then

   FreeLibrary(User32);

inherited;

end;

procedure TTransparentWnd.SetOpaqueHWND(hwnd: THandle);

var

old: THandle;

begin

if IsWindow(hwnd) then

begin

   old := GetWindowLongA(hwnd,GWL_EXSTYLE);

   SetWindowLongA(hwnd, GWL_EXSTYLE, old and ((not 0)-WS_EX_LAYERED));

end;

end;

procedure TTransparentWnd.SetOpaque;

begin

Self.SetOpaqueHWND((Self.Owner as TWinControl).Handle);

end;

procedure TTransparentWnd.SetTransparent;

begin

Self.SetTransparentHWND((Self.Owner as TWinControl).Handle, Self._percent);

end;

procedure TTransparentWnd.SetTransparentHWND(hwnd: THandle; percent : _Percentage);

var

old: THandle;

begin

if (User32 <> 0) and (Assigned(SetLayeredWindowAttributes)) and (IsWindow(hwnd)) then

   if (_auto=true) and (percent=0) then

     SetOpaqueHWND(hwnd)

   else

   begin

     percent := 100 - percent;

     old := GetWindowLongA(hwnd, GWL_EXSTYLE);

     SetWindowLongA(hwnd, GWL_EXSTYLE, old or WS_EX_LAYERED);

     SetLayeredWindowAttributes(hwnd, 0, (255 * percent) div 100, LWA_ALPHA);

   end;

end;

procedure TTransparentWnd.SetTransparent(percent: _Percentage);

begin

Self.SetTransparentHWND((Self.Owner as TForm).Handle, percent);

end;

procedure register;

begin

RegisterComponents('Win32', [TTransparentWnd]);

end;

end.