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Overview |
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Quick Info
Windows NT
| Yes
| Win95
| Yes
| Win32s
| Yes
| Import Library
| user32.lib
| Header File
| winuser.h
| Unicode
| No
| Platform Notes
| None
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InvalidateRect
The InvalidateRect function adds a rectangle to the specified window's update region. The update
region represents the portion of the window's client area that must be
redrawn.
BOOL InvalidateRect(
HWND hWnd,
| // handle of window with changed update region
| CONST RECT *lpRect,
| // address of rectangle coordinates
| BOOL bErase
| // erase-background flag
| );
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Parameters
hWnd
Identifies the window whose update region has changed. If this parameter is
NULL, Windows invalidates and redraws all windows, and sends the WM_ERASEBKGND and WM_NCPAINT messages to the window procedure before the function returns.
lpRect
Points to a RECT structure that contains the client coordinates of the rectangle to be added
to the update region. If this parameter is NULL, the entire client area is added
to the update region.
bErase
Specifies whether the background within the update region is to be erased when
the update region is processed. If this parameter is TRUE, the background is
erased when the BeginPaint function is called. If this parameter is FALSE, the background remains
unchanged.
Return Values
If the function succeeds, the return value is nonzero.
If the function fails, the return value is zero.
Remarks
The invalidated areas accumulate in the update region until the region is
processed when the next WM_PAINT message occurs or until the region is validated by using the ValidateRect or ValidateRgn function.
Windows sends a WM_PAINT message to a window whenever its update region is not
empty and there are no other messages in the application queue for that
window.
If the bErase parameter is TRUE for any part of the update region, the background is erased
in the entire region, not just in the given part.
See Also
BeginPaint, InvalidateRgn, RECT, ValidateRect, ValidateRgn, WM_ERASEBKGND, WM_NCPAINT, WM_PAINT
Related Links
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Unix Manual Pages
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