Re: CView invalidates entire client area on scroll

From:

"AliR" <AliR@online.nospam>

Newsgroups:

microsoft.public.vc.mfc

Date:

Tue, 9 May 2006 16:44:07 -0500

Message-ID:

<44610d47$0$23697$a8266bb1@reader.corenews.com>

ScrollWindow() will case a WM_ERASEBKGND, and a WM_PAINT. No going around
it.

What I ment by handling is that you have to do your own bitblting, you have
to catch the WM_ERASEBKGND
and handle that accordingly (most likely do nothing).

Half of the solution depends on what you are displaying in the window. for
example if you are displaying an image in the window, it will be the same if
you take out the call to ScrollWindow, and instead redraw the window
(Invalidate() UpdateWindow()), while redrawing the window, bitblt using the
Scroll Pos as the source x and y.

AliR.

"Jan M" <jan@acu.no-ip.com> wrote in message
news:OEBTn96cGHA.3348@TK2MSFTNGP03.phx.gbl...

Hi,

I am handling the scrolling (see code snippet).

I just want the stop whatever is invalidating the *entire* client area as
opposed to just the area uncovered by the scroll so I only need to draw

that

in OnDraw().

The MS documentation for CWnd::ScrollWindow() says that the "normal
functionality" is to only invalidate the uncovered region. I'm not getting
that.

Regards,

Jan

"AliR" <AliR@online.nospam> wrote in message
news:4460fda4$0$23755$a8266bb1@reader.corenews.com...

That is the normal functionality. You will have to handle the scrolling
yourself, and do your own bitblting up or down and updating the scrolled
area. If you want MFC to handle the scrolling use CScrollView.

AliR.

"Jan M" <jan@acu.no-ip.com> wrote in message
news:Ox$5jB6cGHA.3712@TK2MSFTNGP03.phx.gbl...

Hi,

I have a WIN2000 application based on CWinApp, CFrameWnd, CDocument,

CView.

CView window style is WS_CHILD|WS_VISIBLE|WS_VSCROLL.

Scrolling the CView (in this case by 1 line) results in the entire

client

area being invalidated not just the area uncovered by the scroll.

I am not calling Invalidate() anywhere in my code. I see a

WM_ERASEBKGND

message sent (from itself) to (and handled by) the CView window after

the

WM_VSCROLL and prior to the WM_PAINT. Presumably this WM_ERASEBKGND

(or

whatever triggered it) is causing the entire client area to be

invalidated.

My scroll code is:

MyCView::OnVScroll()
{
...
  // Sets m_nVscrollPos and nVscrollInc

   SetScrollPos(SB_VERT, m_nVscrollPos, TRUE); // Tried FALSE
   ScrollWindow(0, -m_cyChar * nVscrollInc, NULL, NULL);
}

How can I fix it so I just have to paint the uncovered area when

scrolling?

Thanks,

Jan