CLayeredWindowHelperST v1.0 - A wrapper class for transparent windows


Desktop-as-a-Service Designed for Any Cloud ? Nutanix Frame

Sample Image

SoftechSoftware homepage
SoftechSoftware Email

Environment: VC++ 6.0, XP, Win2k, NT 4.0, Win9x/ME


CLayeredWindowHelperST is a wrapper class of all required APIs to add support for transparent (layered) windows to your applications. This is a scalable class. If running under Windows 2000/XP your windows will have the selected transparent effect, while if running under Windows 9x/ME/NT will run error-less.

How to integrate CLayeredWindowHelperST in your application

In your project include the following files:

  • LayeredWindowHelperST.h
  • LayeredWindowHelperST.cpp
Create a instance of CLayeredWindowHelperST. This class encapsulates all the required APIs to support transparent windows and to run error-less if running under a old Windows version that doesn't support this feature. You need only one instance, so this can be global to the application.
CLayeredWindowHelperST G_Layered;
Modify the style of your window, then set the transparency effect. For dialog-based applications, in your OnInitDialog:
// Call the base-class method

// Modify the style

// Set the trasparency effect to 70%
G_Layered.SetTransparentPercentage(m_hWnd, 70);
G_Layered.SetLayeredWindowAttributes( m_hWnd, 

Class methods

Adds the WS_EX_LAYERED style to the specified window.
This style is required to have a transparent effect.

// Parameters:
//     [IN]   Handle to the window and, indirectly, the 
//             class to which the window belongs. 
//            Windows 95/98/Me: The AddLayeredStyle function 
//             may fail if the window 
//            specified by the hWnd parameter does not belong
//             to the same process as the calling thread. 
// Return value:
//     Non zero
//            Function executed successfully.
//     Zero
//            Function failed. To get extended error 
//            information, call ::GetLastError().
LONG AddLayeredStyle(HWND hWnd)
Sets the opacity and transparency color key of a transparent (layered) window.
// Parameters:
//     [IN]   hWnd
//            Handle to the layered window.
//     [IN]   crKey
//            A COLORREF value that specifies the transparency 
//             color key to be used when
//            composing the layered window. All pixels painted 
//             by the window in this color will be transparent.
//            To generate a COLORREF, use the RGB() macro.
//     [IN]   bAlpha
//            Alpha value used to describe the opacity of the 
//             layered window.
//            When bAlpha is 0, the window is completely 
//             transparent.
//            When bAlpha is 255, the window is opaque. 
//     [IN]   dwFlags 
//            Specifies an action to take. This parameter can 
//             be one or more of the following values:
//               LWA_COLORKEY  Use crKey as the transparency 
//                             color.
//               LWA_ALPHA     Use bAlpha to determine the 
//                             opacity of the layered window.
// Return value:
//     TRUE
//            Function executed successfully.
//     FALSE
//            Function failed. To get extended error 
//             information, call ::GetLastError().
BOOL SetLayeredWindowAttributes( HWND hWnd, 
                                 COLORREF crKey, 
                                 BYTE bAlpha, 
                                 DWORD dwFlags)
Sets the percentage of opacity or transparency of a layered window.
// Parameters:
//     [IN]   hWnd
//            Handle to the layered window.
//     [IN]   byPercentage
//            Percentage (from 0 to 100)
// Return value:
//     Non zero
//            Function executed successfully.
//     Zero
//            Function failed. To get extended error 
//            information, call ::GetLastError().
BOOL SetTransparentPercentage( HWND hWnd, 
                               BYTE byPercentage)
Returns the class version as a short value.
// Return value:
//     Class version. Divide by 10 to get actual version.
static short GetVersionI()
Returns the class version as a string value.
// Return value:
//     Pointer to a null-terminated string 
//      containing the class version.
static LPCTSTR GetVersionC()


To compile CLayeredWindowHelperST you need the Platform SDK (August 2001 or newer). This is not
mandatory because at compile-time, if not found, it will be emulated. At run-time you don't need any
additional SDK or libraries installed.


  • v1.0 (17/January/2002)
    First release


  • There are no comments yet. Be the first to comment!

  • You must have javascript enabled in order to post comments.

Leave a Comment
  • Your email address will not be published. All fields are required.

Most Popular Programming Stories

More for Developers

RSS Feeds

Thanks for your registration, follow us on our social networks to keep up-to-date