This structure contains the window class attributes that are registered by the RegisterClass function.
At a Glance
| Header file: | Winuser.h |
| Windows CE versions: | 1.0 and later |
Syntax
typedef struct _WNDCLASS {
UINT style;
WNDPROC lpfnWndProc;
int cbClsExtra;
int cbWndExtra;
HANDLE hInstance;
HICON hIcon;
HCURSOR hCursor;
HBRUSH hbrBackground;
LPCTSTR lpszMenuName;
LPCTSTR lpszClassName;
} WNDCLASS;
Members
style
Specifies the class style(s). Styles can be combined by using the bitwise OR (|) operator. This member can be any combination of the following values:
| Value | Description |
| CS_DBLCLKS | Sends double-click messages to the window procedure when the user double-clicks the mouse while the cursor is within a window belonging to the class. |
| CS_GLOBALCLASS | Allows an application to create a window of the class regardless of the value of the hInstance parameter passed to the CreateWindow or CreateWindowEx function. If you do not specify this style, the hInstance member passed to the CreateWindow (or CreateWindowEx) function must be the same as the hInstance member passed to the RegisterClass function. |
| You can create a global class by creating the window class in a dynamic-link library (DLL) and listing the name of the DLL in the registry under the following keys: | |
| HKEY_LOCAL_MACHINE\Software \Microsoft\Windows NT\ CurrentVersion\Windows\AppInit_DLLs |
|
| Whenever a process starts, the system loads the specified DLLs in the context of the newly started process before calling the entry-point function in that process. The DLL must register the class during its initialization procedure and must specify the CS_GLOBALCLASS style. | |
| CS_HREDRAW | Redraws the entire window if a movement or size adjustment changes the width of the client area. |
| CS_NOCLOSE | Disables Close on the window menu. |
| CS_PARENTDC | Sets the clipping region of the child window to that of the parent window so that the child can draw on the parent. A window with the CS_PARENTDC style bit receives a regular device context from the system’s cache of device contexts. It does not give the child the parent’s device context or device context settings. Specifying CS_PARENTDC enhances an application’s performance. |
| CS_VREDRAW | Redraws the entire window if a movement or size adjustment changes the height of the client area. |
lpfnWndProc
Long pointer to the window procedure. You must use the CallWindowProc function to call the window procedure. For more information, see WindowProc.
cbClsExtra
Specifies the number of extra bytes to allocate following the window-class structure. The system initializes the bytes to zero.
cbWndExtra
Specifies the number of extra bytes to allocate following the window instance. The system initializes the bytes to zero. If an application uses WNDCLASS to register a dialog box created by using the CLASS directive in the resource file, it must set this member to DLGWINDOWEXTRA.
hInstance
Handle to the instance that the window procedure of this class is within.
hIcon
Unsupported; set to NULL. An application must draw an icon whenever the user minimizes the application window.
hCursor
Handle to the class cursor. This member must be a handle to a cursor resource. If this member is NULL, an application must explicitly set the cursor shape whenever the mouse moves into the application’s window.
hbrBackground
Handle to the class background brush. This member can be a handle to the physical brush to be used for painting the background, or it can be a color value. A color value must be one of the following standard system colors (the value 1 must be added to the chosen color). If a color value is given, you must convert it to one of the following HBRUSH types:
| COLOR_ACTIVEBORDER | COLOR_HIGHLIGHTTEXT |
| COLOR_ACTIVECAPTION | COLOR_INACTIVEBORDER |
| COLOR_APPWORKSPACE | COLOR_INACTIVECAPTION |
| COLOR_BACKGROUND | COLOR_MENU |
| COLOR_BTNFACE | COLOR_MENUTEXT |
| COLOR_BTNSHADOW | COLOR_SCROLLBAR |
| COLOR_BTNTEXT | COLOR_WINDOW |
| COLOR_CAPTIONTEXT | COLOR_WINDOWFRAME |
| COLOR_GRAYTEXT | COLOR_WINDOWTEXT |
| COLOR_HIGHLIGHT |
The system automatically deletes class background brushes when the class is freed. An application should not delete these brushes, because a class may be used by multiple instances of an application.
When this member is NULL, an application must paint its own background whenever it is requested to paint in its client area. To determine whether the background must be painted, an application can either process the WM_ERASEBKGND message or test the fErase member of the PAINTSTRUCT structure filled by the BeginPaint function.
lpszMenuName
Long pointer to a null-terminated character string that specifies the resource name of the class menu, as the name appears in the resource file. If you use an integer to identify the menu, use the MAKEINTRESOURCE macro. If this member is NULL, windows belonging to this class have no default menu.
lpszClassName
Either a long pointer to a null-terminated string or an atom. If this member is an atom, it must be a global atom created by a previous call to the GlobalAddAtom function. The atom, a 16-bit value, must be in the low-order word of lpszClassName; the high-order word must be zero.
If lpszClassName is a string, it specifies the window class name.
Remarks
The following members are restricted.
In Windows CE, all window classes are process global. The CS_GLOBALCLASS value is included to provide source level compatibility with applications that are also compiled under other versions of Windows.
Note
The technique of putting a class name and DLL in the registry and having a DLL automatically loaded is not supported.
See Also
BeginPaint, CreateWindow, CreateWindowEx, GetDC, MAKEINTRESOURCE, PAINTSTRUCT, RegisterClass, WindowProc, WM_PAINT