ScrollWindow and ScrollWindowEX question
in [MFC]
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From: Ririko Horvath on 24 Feb 2005 06:26 Hello, The contents of a window's client area gets garbled by scrolling when 'ScrollWindow' or 'ScrollWindowEx' followed by UpdateWindowis used to scroll the contents of a window's client area. Does anyone know what is an easiest way to overcome this problem. Thank You!
From: Scott McPhillips [MVP] on 24 Feb 2005 07:54 Ririko Horvath wrote: > Hello, > > The contents of a window's client area gets garbled by scrolling when > 'ScrollWindow' or 'ScrollWindowEx' followed by UpdateWindowis used to > scroll the contents of a window's client area. Does anyone know what is an > easiest way to overcome this problem. > > Thank You! > > ScrollWindow copies the existing pixels to their new position and invalidates only the thin strip at the edge that needs new pixels. So UpdateWindow clips painting to the new strip because it is the only part that has been invalidated. If you need to repaint more than the new strip after a scroll then you should add a call to Invalidate() in OnHScroll or OnVScroll. This will change the clipping region to the entire client area of the window. -- Scott McPhillips [VC++ MVP]
From: Ririko Horvath on 24 Feb 2005 08:34 I called Invalidate() (tried passing both true and false) from OnHScroll. Unfortunately it stopped the scrolling of the window's client area. The code I am using is as follows: // from OnHScroll if (si.nPos != xPos) { m_ListBox.ScrollWindow(xPos - si.nPos, 0, NULL,NULL); Invalidate(true); /* also tried m_ListBox.Invalidate(true); */ } Can you tell me waht I am doing wrong? Thank You! "Scott McPhillips [MVP]" <org-dot-mvps-at-scottmcp> wrote in message news:eoifWCnGFHA.2752(a)TK2MSFTNGP12.phx.gbl... > Ririko Horvath wrote: > > Hello, > > > > The contents of a window's client area gets garbled by scrolling when > > 'ScrollWindow' or 'ScrollWindowEx' followed by UpdateWindowis used to > > scroll the contents of a window's client area. Does anyone know what is an > > easiest way to overcome this problem. > > > > Thank You! > > > > > > ScrollWindow copies the existing pixels to their new position and > invalidates only the thin strip at the edge that needs new pixels. So > UpdateWindow clips painting to the new strip because it is the only part > that has been invalidated. > > If you need to repaint more than the new strip after a scroll then you > should add a call to Invalidate() in OnHScroll or OnVScroll. This will > change the clipping region to the entire client area of the window. > > -- > Scott McPhillips [VC++ MVP] >
From: Scott McPhillips [MVP] on 24 Feb 2005 09:10 Ririko Horvath wrote: > I called Invalidate() (tried passing both true and false) from OnHScroll. > Unfortunately it stopped the scrolling of the window's client area. The code > I am using is as follows: > > // from OnHScroll > if (si.nPos != xPos) { > m_ListBox.ScrollWindow(xPos - si.nPos, 0, NULL,NULL); > Invalidate(true); > /* also tried > m_ListBox.Invalidate(true); > */ > } > > Can you tell me waht I am doing wrong? > > Thank You! I assume m_ListBox is a CListBox? What you seem to be doing here is messing with the painted image of the list box without informing the list box code of the desired new position. So it doesn't know what you want where. You should not expect the list box to respond in any way to the parent's scroll bars. -- Scott McPhillips [VC++ MVP]
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