How-to-AlphaBlend-your-forms-with-a-component


            Title: How to AlphaBlend your forms with a component!
Question: Do you like the AlphaBlending of Windows 2000 menus? Use that and you'll implement in your applications.
Answer:
Unit uAlphaWindow;
Interface
Uses
 Windows, Messages, Classes, Controls, Forms;
Type
 TAlphaPercent = 0..100;
 TAlphaWindow =
 Class( TComponent )
 Protected
 User32 : HModule;
 Public
 Constructor Create( AOwner : TComponent ); OverRide;
 Destructor Destroy; OverRide;
 Procedure SetTransparentHWND( HWnd : THandle; Percent : TAlphaPercent );
 Procedure SetTransparent( Percent : TAlphaPercent );
 Procedure SetOpaqueHWND( HWnd : THandle );
 Procedure SetOpaque;
 End;
 Procedure Register;
Implementation
Const
 LWA_ALPHA = $2;
 GWL_EXSTYLE = -20;
 WS_EX_LAYERED = $80000;
 WS_EX_TRANSPARENT = $20;
Var
 SetLayeredWindowAttributes : Function( HWnd : LongInt; crKey : Byte; bAlpha : Byte; dwFlags : LongInt ) : LongInt; StdCall;
Constructor TAlphaWindow.Create( AOwner : TComponent );
Begin
 Inherited;
 User32 := LoadLibrary( 'USER32.DLL' );
 If ( User32 0 ) Then
 @SetLayeredWindowAttributes := GetProcAddress( User32, 'SetLayeredWindowAttributes' )
 Else
 SetLayeredWindowAttributes := NIL;
End;
Destructor TAlphaWindow.Destroy;
Begin
 If ( User32 0 ) Then FreeLibrary( User32 );
 Inherited;
End;
Procedure TAlphaWindow.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 TAlphaWindow.SetOpaque;
Begin
 Self.SetOpaqueHWND( ( Self.Owner As TWinControl ).Handle );
End;
Procedure TAlphaWindow.SetTransparentHWND( HWnd : THandle; Percent : TAlphaPercent );
Var
 Old : THandle;
Begin
 If ( ( User32 0 ) And ( Assigned( SetLayeredWindowAttributes ) ) And ( IsWindow( HWnd ) ) ) Then
 If ( 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 TAlphaWindow.SetTransparent( Percent : TAlphaPercent );
Begin
 Self.SetTransparentHWND( ( Self.Owner As TForm ).Handle, Percent );
End;
Procedure Register;
Begin
 RegisterComponents( 'Christian', [ TAlphaWindow ] );
End;
End.
Forms Delphi
