Re: why old text with textOut cleared !!

From:
"David Ching" <dc@remove-this.dcsoft.com>
Newsgroups:
microsoft.public.vc.mfc
Date:
Sun, 4 Oct 2009 09:57:01 -0700
Message-ID:
<OqwxxORRKHA.1232@TK2MSFTNGP05.phx.gbl>
"hadi kazemi" <hadikazemi@discussions.microsoft.com> wrote in message
news:13A9809F-DDE6-4A6A-8D81-7A74DA6E2B44@microsoft.com...

hi
i use these code for add some text in my window:

[code]

       case WM_PAINT:
           hdc = BeginPaint(hWnd, &ps);
TextOut (hdc, 90, 0,
L"Welcome To DirectX Sound Recorder.",
lstrlen (L"Welcome To DirectX Sound Recorder.")) ;
if(whatPrint == 'i'){
TextOut (hdc, 0, 2 * cyChar,
L"Ready For Start...",
lstrlen (L"Ready For Start...")) ;
}else if (whatPrint == 'r'){
TextOut (hdc, 0, indexOfLineForPrint * cyChar,
L"Recording... ",
lstrlen (L"Recording... ")) ;
//indexOfLineForPrint++;
}else if (whatPrint == 's'){
TextOut (hdc, 0, indexOfLineForPrint * cyChar,
L"Stop! ",
lstrlen (L"Stop! ")) ;
//indexOfLineForPrint++;
}
EndPaint(hWnd, &ps);
           break;

[/code]

when i want add some text do like this:

[code]

whatPrint = 'n';
InvalidateRect(g_hWnd,NULL,FALSE);

[/code]

but when i minimize window and maximize it again. i see all text instead
last text cleared. how can i solve this problem ?


You call InvalidateRect with the last parameter (bErase) set to FALSE,
meaning your WM_PAINT will be called without erasing the prior contents.

You should not assume in your WM_PAINT that you are starting with a blank
window, as you can see Windows can call it whenever it wants, and in this
case your window contains the previous contents. You can either make the
window blank in your WM_PAINT yourself (such as doing a FillSolidRect() with
the background color).

-- David

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-- Stansfield Turner (Rhodes scholar),
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