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WM_SIZING message

Applies to: desktop apps only

Sent to a window that the user is resizing. By processing this message, an application can monitor the size and position of the drag rectangle and, if needed, change its size or position.

A window receives this message through its WindowProc function.

Copy 
#define WM_SIZING                       0x0214

Parameters

wParam

The edge of the window that is being sized. This parameter can be one of the following values.

ValueMeaning
WMSZ_BOTTOM
6

Bottom edge

WMSZ_BOTTOMLEFT
7

Bottom-left corner

WMSZ_BOTTOMRIGHT
8

Bottom-right corner

WMSZ_LEFT
1

Left edge

WMSZ_RIGHT
2

Right edge

WMSZ_TOP
3

Top edge

WMSZ_TOPLEFT
4

Top-left corner

WMSZ_TOPRIGHT
5

Top-right corner

 

lParam

A pointer to a RECT structure with the screen coordinates of the drag rectangle. To change the size or position of the drag rectangle, an application must change the members of this structure.

Return value

Type: LRESULT

An application should return TRUE if it processes this message.

Requirements

Minimum supported client

Windows 2000 Professional

Minimum supported server

Windows 2000 Server

Header
Winuser.h (include Windows.h)

See also

Reference
WM_MOVING
WM_SIZE
Conceptual
Windows
Other Resources
RECT

 

 

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Build date: 2/3/2012

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Values in C# 
internal const int WM_SIZING = 0x0214;
internal const int WMSZ_LEFT = 1;
internal const int WMSZ_RIGHT = 2;
internal const int WMSZ_TOP = 3;
internal const int WMSZ_TOPLEFT = 4;
internal const int WMSZ_TOPRIGHT = 5;
internal const int WMSZ_BOTTOM = 6;
internal const int WMSZ_BOTTOMLEFT = 7;
internal const int WMSZ_BOTTOMRIGHT = 8;
History
WindowsX.h 
#ifndef HANDLE_WM_SIZING
/* BOOL Cls_OnSizing(HWND hwnd, UINT fSide, LPRECT lprc) */
#define HANDLE_WM_SIZING(hwnd, wParam, lParam, fn) \
    MAKELRESULT((BOOL)(fn)((hwnd), (UINT)(wParam), (LPRECT)(lParam)), 0L)
#define FORWARD_WM_SIZING(hwnd, fSide, lprc, fn) \
    (BOOL)(DWORD)(fn)((hwnd), WM_SIZING, (WPARAM)(UINT)(fSide), (LPARAM)(LPRECT)(lprc))
#endif

History
Value 
WM_SIZING = &H214
Private Const WMSZ_BOTTOM As Int32 = 6
Private Const WMSZ_BOTTOMLEFT As Int32 = 7
Private Const WMSZ_BOTTOMRIGHT As Int32 = 8
Private Const WMSZ_LEFT As Int32 = 1
Private Const WMSZ_RIGHT As Int32 = 2
Private Const WMSZ_TOP As Int32 = 3
Private Const WMSZ_TOPLEFT As Int32 = 4
Private Const WMSZ_TOPRIGHT As Int32 = 5

History