DefSubclassProc function (commctrl.h)
Calls the next handler in a window's subclass chain. The last handler in the subclass chain calls the original window procedure for the window.
Syntax
LRESULT DefSubclassProc(
[in] HWND hWnd,
[in] UINT uMsg,
[in] WPARAM wParam,
[in] LPARAM lParam
);
Parameters
[in] hWnd
Type: HWND
A handle to the window being subclassed.
[in] uMsg
Type: UINT
A value of type unsigned int that specifies a window message.
[in] wParam
Type: WPARAM
Specifies additional message information. The contents of this parameter depend on the value of the window message.
[in] lParam
Type: LPARAM
Specifies additional message information. The contents of this parameter depend on the value of the window message. Note: On 64-bit versions of Windows LPARAM is a 64-bit value.
Return value
Type: LRESULT
The returned value is specific to the message sent. This value should be ignored.
Remarks
You do not need to call the default window procedure; this function calls it automatically.
The SUBCLASS module defines helper functions that are used to subclass windows. The code maintains a single property on the subclassed window and dispatches various subclass callbacks to its clients as required. The client is provided reference data and a default processing API.
A subclass callback is identified by a unique pairing of a callback function pointer and an unsigned ID value. Each callback can also store a single DWORD of reference data, which is passed to the callback function when it is called to filter messages. No reference counting is performed for the callback; it may repeatedly call SetWindowSubclass to alter the value of its reference data element.
Requirements
| Requirement | Value |
|---|---|
| Minimum supported client | Windows XP [desktop apps only] |
| Minimum supported server | Windows Server 2003 [desktop apps only] |
| Target Platform | Windows |
| Header | commctrl.h |
| Library | Comctl32.lib |
| DLL | Comctl32.dll (version 5.8 or later) |
| API set | ext-ms-win-shell-comctl32-window-l1-1-0 (introduced in Windows 10, version 10.0.14393) |