mainstream Цитата: сделать прозрачный компонент
Вот, по вашей просьбе нашёл статью в Delphi World
"Полупрозрачная форма в Win2000"
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Обнаружил в Windows 2000 полноценную реализацию полупрозрачности:
Код: const
WS_EX_LAYERED = $80000;
LWA_COLORKEY = 1;
LWA_ALPHA = 2;
function SetLayeredWindowAttributes(
hwnd : HWND; // handle to the layered window
crKey : TColor; // specifies the color key
bAlpha : byte; // value for the blend function
dwFlags : DWORD // action
): BOOL; stdcall;
function SetLayeredWindowAttributes; external 'user32.dll';
procedure TForm1.FormCreate(Sender: TObject);
begin
if SetWindowLong(Handle, GWL_EXSTYLE, GetWindowLong(Handle, GWL_EXSTYLE)
or WS_EX_LAYERED) = 0 then
ShowMessage(SysErrorMessage(GetLastError));
if not SetLayeredWindowAttributes(Handle, 0, 128, LWA_ALPHA) then
// ^^^ степень прозрачности
// 0 - полная прозрачность
// 255 - полная непрозрачность
ShowMessage(SysErrorMessage(GetLastError));
end;
Есть более продвинутые возможности (например, альфа-канал в битмапе)
http://msdn.microsoft.com/isapi/msdnlib.idc?theURL=/library/techart/layerwin.htm 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.
!!!!