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GPL and MS DirectX DirectDraw

From: PrussianSnow
Subject: GPL and MS DirectX DirectDraw
Date: Tue, 22 Jun 2004 04:02:51 +0100

Hi all,

I am currently developing a library which I intend to release under the GNU 
GPL. (Yes, the GPL, not the LGPL... for my own little neurotic reasons.)

However, I would like to make a version of this library which is capable of 
running under MS Windows to facilitate porting of application using the library 
onto this platform. However, the only way I have found to obtain acceptable 
graphics performance is to use the DirectDraw portion of the MS DirectX system 
in order to bypass the Windows graphics subsystem. (It's working so that's not 
the issue...)

The problem I am having is in clarifying the licensing issues raised by 
combining GPL software with MS DirectX.

Obviously I don't have the code for DirectX but it looks like DirectX would 
easily fall under the standard OS component exception in the GPL. All versions 
of Windows starting somewhere around Windows 95 have shipped with some version 
of DirectX so this is a strong argument in my opinion.

HOWEVER, in order to use DirectX I need to use an include file for DirectDraw. 
Microsoft makes the required file, DDRAW.H, available for download in their 
DirectX SDK so I can just point users at this is they want to re-compile but 
then I'm not really including all the source am I? Also, there is no saying if 
Microsoft will pull this file off their servers or charge for it next week or 
next year, or some other scenario; so where do I stand? (PS The standard 
include file works without modification under MingW so I don't have to worry 
about distributing a modified file--I just need to justify not including the 
copyrighted file.)

The executable raises some other questions. I guess I can't statically link to 
a DirectX library so I have to at least link at runtime to a DirectX DLL, what 
are the implications of this? (I don't want to write a wrapper for DirectDraw, 
place it in the public domain and then link to that... although this is an 
interesting hypothetical situation for comparison.)

I'm sure there are other GPL apps (or ports thereof) out there that have run 
into this particular scenario as DirectX is used extensively under Windows. 
Anyone have any good suggestions regarding where I can find some more 


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