Yes, Fl_Window::make_current() seems to work for me too. Anyway, I have written much faster fl_read_image() for windows based on GetDIBits() function (original one is bloody slow as it reads data on per-pixel basis) so I will submit that as an STR - but it should be revised by somebody more familiar with win32 GDI (works for me thought)...
Thank you, R. imacarthur wrote: > > On 25 Jun 2010, at 18:01, Roman Kantor wrote: > >> Hi, I have encountered problem that fl_create_offscreen() fails on >> certain platforms (win 7) under certain circumstances, eg when called >> from menu. This problem appears only on some platforms - like win 7 (on >> win XP it seems to work fine). >> >> Under further investigation it looks like it is caused by the fact that >> fl_gc is NULL (probably fl_gc is reset to 0 after menu window is closed >> - maybe the callback is called AFTER the menu window destructuion?) at >> that stage and CreateCompatibleBitmap() function (within >> fl_create_offscreen()) does not have a valid DC reference. This means >> that it is safe to call fl_create_ofscreen() only within draw() methods >> when fl_gc is valid. >> >> I have resolved (made work-around) the problem by postponing the calls >> to offscreen functions during redraw but in general I believe that it >> should be possible to create/manipulate offscreens at any time. >> >> Any thoughts from Win32 API gurus? > > I'm not a win32 API guru by any stretch, but I have observed the same > (or very similar) effect on WinVista in the past, with code that works > OK on Linux and OSX (and I *think* WinXP). > > What I did was add a make_current() call, based on the apps main window, > just before creating the offscreen for the first time. (I think I did > this for all platforms, not just #ifdef WIN32, and it seemed to be safe > enough...) > > That seemed to be god enough to get things working robustly. _______________________________________________ fltk mailing list [email protected] http://lists.easysw.com/mailman/listinfo/fltk
