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Bug 907

Summary: SDL window restore SDL_VIDEORESIZE event issue...
Product: SDL Reporter: cjj_009
Component: eventsAssignee: Sam Lantinga <slouken>
Status: RESOLVED FIXED QA Contact: Sam Lantinga <slouken>
Severity: normal    
Priority: P2    
Version: 1.2.14   
Hardware: x86   
OS: Windows Vista   
Attachments: Simple C++ openGL/SDL program to demonstrate SDL_VIDEORESIZE issue
Proposed patch for SDL_resize.c

Description cjj_009 2009-12-14 20:32:35 UTC 
Created attachment 464 [details]
Simple C++ openGL/SDL program to demonstrate SDL_VIDEORESIZE issue

I've been working on an SDL/OpenGL program, that among other things, must deal
with resizing events in order to adjust the aspect ratio.
It doesn't always seem to get the SDL_VIDEORESIZE event when it should, causing
the aspect ratio to not be adjusted as needed.

I've run it in debug mode and made these observations:
*When it initially starts up, if I maximize the window, it receives the
SDL_VIDEORESIZE event as needed.
*If, after starting up the the application and maximizing the window, I then
restore the window by double clicking the title bar, it does NOT receive the
SDL_VIDEORESIZE event.
*I can repeat the last two steps, and it will get continue to get the
SDL_VIDEORESIZE on the maximize but not get one on the restore.
*If I then do a slight adjustment to the width or height of the window, it will
get the SDL_VIDEORESIZE event.
*From then on, if I do restore operations to the window, the SDL_VIDEORESIZE
event will be caught properly.

I included a simple Open GL rotating pyramid program to demonstrate the
problem, written in Visual C++ 2008 Express.  The steps above should produce
the error, in which case you will see an incorrect aspect ratio on the scene. 
A Win32 function to create a message box is included at the problem point, but
remarked out.  Uncomment it if you wish to use it.

See http://forums.libsdl.org/viewtopic.php?t=5291 for additional information.
See the attached Visual Studio solution (includes one .cpp file) for the
example program.
Comment 1 vgvgf 2010-03-28 15:15:16 UTC 
Created attachment 502 [details]
Proposed patch for SDL_resize.c

The width and height values stored in SDL_VideoSurface are the sizes of the video surface when it was created. So, when the window is rezised back to its creation size, the following condition will make the SDL_PrivateResize function stop, and the video resize msg won't be queued.
if ( ! SDL_VideoSurface ||
     ((w == SDL_VideoSurface->w) && (h == SDL_VideoSurface->h)) ) {
	return(0);
}
Comment 2 Sam Lantinga 2011-12-30 02:59:51 UTC 
I'm okay with applying this patch, but be aware that the expected response to a resize message is that you call SDL_SetVideoMode() again with the new mode.  This signals SDL that you're expecting the new size, and there may be other problems if you don't do this.
Comment 3 Sam Lantinga 2011-12-30 03:02:27 UTC 
The patch is in, thanks!
http://hg.libsdl.org/SDL/rev/f56b95794ac8