|
Overview |
|
|
|
Group |
|
|
|
Quick Info
Windows NT
| Yes
| Win95
| Yes
| Win32s
| Yes
| Import Library
| user32.lib
| Header File
| winuser.h
| Unicode
| WinNT
| Platform Notes
| None
|
|
|
SetWindowLong
The SetWindowLong function changes an attribute of the specified window. The function also sets
a 32-bit (long) value at the specified offset into the extra window memory of
a window.
LONG SetWindowLong(
HWND hWnd,
| // handle of window
| int nIndex,
| // offset of value to set
| LONG dwNewLong
| // new value
| );
|
|
Parameters
hWnd
Identifies the window and, indirectly, the class to which the window belongs.
nIndex
Specifies the zero-based offset to the value to be set. Valid values are in
the range zero through the number of bytes of extra window memory, minus 4; for
example, if you specified 12 or more bytes of extra memory, a value of 8 would
be an index to the third 32-bit integer. To set any other value, specify one of
the following values:
Value
| Action
| GWL_EXSTYLE
| Sets a new extended window style.
| GWL_STYLE
| Sets a new window style.
| GWL_WNDPROC
| Sets a new address for the window procedure.
| GWL_HINSTANCE
| Sets a new application instance handle.
| GWL_ID
| Sets a new identifier of the window.
| GWL_USERDATA
| Sets the 32-bit value associated with the window. Each window has a
corresponding 32-bit value intended for use by the application that created the window.
|
The following values are also available when the hWnd parameter identifies a dialog box:
Value
| Action
| DWL_DLGPROC
| Sets the new address of the dialog box procedure.
| DWL_MSGRESULT
| Sets the return value of a message processed in the dialog box procedure.
| DWL_USER
| Sets new extra information that is private to the application, such as handles
or pointers.
|
dwNewLong
Specifies the replacement value.
Return Values
If the function succeeds, the return value is the previous value of the
specified 32-bit integer.
If the function fails, the return value is zero. To get extended error
information, call GetLastError.
If the previous value of the specified 32-bit integer is zero, and the
function succeeds, the return value is zero, but the function does not clear the last
error information. This makes it difficult to determine success or failure. To
deal with this, you should clear the last error information by calling SetLastError(0) before calling SetWindowLong. Then, function failure will be indicated by a return value of zero and a GetLastError result that is nonzero.
Remarks
The SetWindowLong function fails if the window specified by the hWnd parameter does not belong to the same process as the calling thread.
If you use the SetWindowLong function and the GWL_WNDPROC index to replace the window procedure, the
window procedure must conform to the guidelines specified in the description of the WindowProc callback function.
Calling SetWindowLong with the GWL_WNDPROC index creates a subclass of the window class used to
create the window. An application should not subclass a window created by another
process. The SetWindowLong function creates the window subclass by changing the window procedure
associated with a particular window, causing Windows to call the new window procedure
instead of the previous one. An application must pass any messages not
processed by the new window procedure to the previous window procedure by calling CallWindowProc. This allows the application to create a chain of window procedures.
Reserve extra window memory by specifying a nonzero value in the cbWndExtra member of the WNDCLASS structure used with the RegisterClass function.
You must not call SetWindowLong with the GWL_HWNDPARENT index to change the parent of a child window.
Instead, use the SetParent function.
See Also
CallWindowProc, GetWindowLong, GetWindowWord, RegisterClass, SetParent, SetWindowWord, WindowProc, WNDCLASS
| Last news from Greatis Software |
 |
|
Nostalgia .Net |
|
.Net is powerful, but not all-powerful, so sometimes we need to use Win32 API for our .Net applications. It's simple enough with Platform Invoke if you have Win32 skill, but we do not always have time to dig the ancient documentation, declare the special types that are compatible with Win32, find the values of the Win32's constants and so on. Nostalgia .Net offers several simple-to-use classes, and components that will allow you to forget about the headache of Win32 and just use the power of Win32 in your application the same way as you use the native. Net classes. More » |
| Recommended software for developers |
 |
|
Ultimate Pack |
|
Component pack for Delphi and C++ Builder that contains runtime form designer, runtime object inspector, print suite and much more for the very special price. More » |
 |
|
Form Designer .Net |
|
Unique runtime form design solution that allows to edit any form in .Net WinForms application at runtime with full source codes for only 300 euro! More » |
 |
|
Print Suite .Net |
|
Print Suite .Net is a set of components for easy printing texts, images and grids from your WinForms applications. Full C# source codes are available More » |
 |
|
Gradient Controls .Net |
|
Gradient Controls .Net offers controls with gradient background feature. Labels, panels and so on... Full C# source codes are available More » |
 |
|
Greatis iGrid |
|
iGrid plots drawing grid right over your desktop, so you can use it everywhere, with any drawing application without any special plugins for different graphic editors. More » |
All the contacts and projectsDmitry Vasiliev (just.dmitry)
Related LinksSoftware for Visual Studio .NET developers
Software for Delphi and C++ Builder developers
Software for Visual Basic 6 developers
Delphi Tips&Tricks
MegaDetailed.NET More Online Helps Win32 Programmer's Reference
Win32 Multimedia Programmer's Reference
OLE Programmer's Reference
Microsoft Windows Pen API Programmer's Reference
Microsoft Windows Sockets 2 Reference
Microsoft Windows Telephony API (TAPI) Programmer's Reference
Unix Manual Pages
|
