From: "Steve Pick" <[EMAIL PROTECTED]>
I've recently been looking into the flickering resize in win32::gui. The
most compatible solution to this I've found is extremely (and very
annoyingly) simple. Just add the style WS_CLIPCHILDREN to your window or
dialog box.
Steve,
I've just tried this and it works...Well, sort of:) On XP, any window behind
the window being resized tear as they are redrawn. Also, for some reason
there seems to be a delay in some of the events to any window with
WS_CLIPCHILDREN set (!?). In my case, it means I can't use WS_CLIPCHILDREN
which is a shame since the application looks and feels so *much* better
without the flicker.
Doing a little searching I came across this page
http://www.catch22.org.uk/tuts/flicker.asp
===========
WM_ERASEBKGND
The prime suspect is usually the WM_ERASEBKGND message. This message is sent
to a window when it's background needs to be erased. This happens because
windows are usually painted using a 2-stage process:
WM_ERASEBKGND: Clear the background
WM_PAINT: Draw the contents on top
....
Right then, how do we avoid erasing the background of a window? There are
two methods.
Set the window's background brush to NULL. (Set the hbrBackground member of
the WNDCLASS structure to zero when you register the window class).
Return non-zero in the WM_ERASEBKGND message handler.
Any one of these will steps will prevent the WM_ERASEBKGND message from
clearing the window. The last option is usually easiest to implement:
case WM_ERASEBKGND:
return 1;
It is also possible to prevent WM_ERASEBKGND when you invalidate and update
a window. The InvalidateRect API call's last parameter specifies whether or
not a portion of a window is to have it's background erased when it is next
redrawn. Specifying FALSE for this paramter prevents WM_ERASEBKGND from
being sent when the window is redrawn.
InvalidateRect(hwnd, &rect, FALSE);
============
I've no idea how to write a message handler for WM_ERASEBKGND - any ideas?
I've played with InvalidateRect in the past but didn't get anywhere fast.
I tried to implement double-buffering in GUI.xs (I was working with 0.0.558
at the time) but frankly I failed.
Have a look at some of the code in this page:
http://www.codeproject.com/gdi/flickerfree.asp
"This article presents a class called CMemDC that encapsulates most of the
issues associated with writing to off-screen buffers. Adding CMemDC to an
existing application or MFC Active X control is nearly trivial.
Modifying an MFC Application to use CMemDC
Add the file memdc.h in your project.
Add the line #include "memdc.h" to stdafx.h.
Add a windows message handler for WM_ERASEBKGND. "
Would it be hard to incorporate it into GUI.xs somehow? The code is
opensource.
Cheers,
jez.
_________________________________________________________________
Find a cheaper internet access deal - choose one to suit you.
http://www.msn.co.uk/internetaccess
