Jeremy, > Doing a little searching I came across this page > http://www.catch22.org.uk/tuts/flicker.asp
The page gives good advice and does exactly what I've already done with double-buffering. However the problem is that double buffering requires that widgets are drawn when the main window receives WM_PAINT. Win32::GUI by default doesnt seem to handle WM_PAINT at all in the window event loop, and widgets all seem to be drawn somewhere else, and I'm not experienced enough to fix that. > Have a look at some of the code in this page: > > http://www.codeproject.com/gdi/flickerfree.asp I dont think I can use this, it seems to do exactly what I've already tried to implement with my own code, but it doesnt look like it's for drawing *widgets*. While it claims that converting an MFC app to flickerless mode is "easy" it actually looks too difficult for me to do it with Win32::GUI, for exactly the same reason as given above; I cant find where widgets are drawn. Steve ----- Original Message ----- From: "Jeremy White" <[EMAIL PROTECTED]> To: <[EMAIL PROTECTED]>; <perl-win32-gui-users@lists.sourceforge.net> Sent: Sunday, November 16, 2003 5:16 PM Subject: Re: [perl-win32-gui-users] Solution: flicker in Win32::GUI > >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 > > > > ------------------------------------------------------- > This SF. Net email is sponsored by: GoToMyPC > GoToMyPC is the fast, easy and secure way to access your computer from > any Web browser or wireless device. Click here to Try it Free! > https://www.gotomypc.com/tr/OSDN/AW/Q4_2003/t/g22lp?Target=mm/g22lp.tmpl > _______________________________________________ > Perl-Win32-GUI-Users mailing list > Perl-Win32-GUI-Users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/perl-win32-gui-users >
