The WNDCLASSEX structure contains window class information. It is used with the RegisterClassEx and GetClassInfoEx functions.
The WNDCLASSEX structure is similar to the WNDCLASS structure. There are two differences. WNDCLASSEX includes the cbSize member, which specifies the size of the structure, and the hIconSm member, which contains a handle to a small icon associated with the window class.
typedef struct _WNDCLASSEX {
UINT cbSize;
UINT style;
WNDPROC lpfnWndProc;
int cbClsExtra;
int cbWndExtra;
HANDLE hInstance;
HICON hIcon;
HCURSOR hCursor;
HBRUSH hbrBackground;
LPCTSTR lpszMenuName;
LPCTSTR lpszClassName;
HICON hIconSm;
} WNDCLASSEX;
| Value | Action |
|---|---|
| CS_BYTEALIGNCLIENT | Aligns the window's client area on the byte boundary (in the x direction). This style affects the width of the window and its horizontal position on the display. |
| CS_BYTEALIGNWINDOW | Aligns a window on a byte boundary (in the x direction). This style affects the width of the window and its horizontal position on the display. |
| CS_CLASSDC | Allocates one device context to be shared by all windows in the class. Because window classes are process specific, it is possible for multiple threads of an application to create a window of the same class. It is also possible for the threads to attempt to use the device context simultaneously. When this happens, the system allows only one thread to successfully finish its drawing operation. For more information, see Device Contexts. |
| 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 CreateWindowEx function. If you do not specify this style, the hInstance parameter passed to the CreateWindow (or CreateWindowEx) function must be the same as the hInstance parameter passed to the RegisterClassEx 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_OWNDC | Allocates a unique device context for each window in the class. For more information, see Device Contexts. |
| 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. For more information, see Device Contexts. |
| CS_SAVEBITS | Saves, as a bitmap, the portion of the screen image obscured by a window. The system uses the saved bitmap to re-create the screen image when the window is removed. The system displays the bitmap at its original location and does not send WM_PAINT messages to windows obscured by the window if the memory used by the bitmap has not been discarded and if other screen actions have not invalidated the stored image. This style is useful for small windows (for example, menus or dialog boxes) that are displayed briefly and then removed before other screen activity takes place. This style increases the time required to display the window, because the system must first allocate memory to store the bitmap. |
| CS_VREDRAW | Redraws the entire window if a movement or size adjustment changes the height of the client area. |
COLOR_ACTIVEBORDER
COLOR_ACTIVECAPTION
COLOR_APPWORKSPACE
COLOR_BACKGROUND
COLOR_BTNFACE
COLOR_BTNSHADOW
COLOR_BTNTEXT
COLOR_CAPTIONTEXT
COLOR_GRAYTEXT
COLOR_HIGHLIGHT
COLOR_HIGHLIGHTTEXT
COLOR_INACTIVEBORDER
COLOR_INACTIVECAPTION
COLOR_MENU
COLOR_MENUTEXT
COLOR_SCROLLBAR
COLOR_WINDOW
COLOR_WINDOWFRAME
COLOR_WINDOWTEXT
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.
If lpszClassName is a string, it specifies the window class name.
Windows NT: Requires version 3.5 or later.
Windows: Requires Windows 95 or later.
Windows CE: Unsupported.
Header: Declared in winuser.h.
Unicode: Defined as Unicode and ANSI structures.
Window Classes Overview, Window Class Structures, GetClassInfoEx, RegisterClassEx