adding doc for how DdCreateDirectDrawObject (GdiEntry1) and DdDeleteDirectDrawObject (GdiEntry3) works in reactos. doc by request by some devlopers

svn path=/trunk/; revision=21852

reactos/media/doc/DdCreateDirectDrawObject.txt

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+DdCreateDirectDrawObject  
+
+When IN HDC is not NULL
+1. we need check the IN HDC is NULL or not
+2. if it not null we need create a directdraw handler 
+   and store it to pDirectDrawGlobal->hDD
+3. if the directdraw handle is null return false
+   we did fail to create directdraw HAL 
+4. if the directdraw handle was not null we return true
+   we did susses to create directdraw HAL 
+ 
+When IN HDC is NULL   
+Now we come to if IN HDC is null basic we need create
+   a hdc and cashe some data
+1. if internal cache of directdraw handle is not null (pDirectDrawGlobalInternal->hDD)
+   we take it and fill to the public directdraw handler (pDirectDrawGlobal->hDD)
+   and return susses.
+ 
+2.  if no internal cache of directdraw handle is found we need create it
+    by using CreateDC for tempary HDC that will be cache in the win32k later
+ 
+3.  we need check see if we got a tempary HDC or not, if we fail getting tempary 
+    HDC return FALSE
+ 
+4. Now we trying create directdraw handler it being cache to (pDirectDrawGlobalInternal->hDD)
+   and it also set same handler to the public (pDirectDrawGlobal->hDD)
+5. if it fails to create directdraw handle return false
+   we did fail to create directdraw HAL 
+6. if it susses create directdraw handle return true
+   we did susses to create directdraw HAL    
+ 
+To create a directdraw handler you need call the NtGdiDdCreateDirectDrawObject with a hdc

reactos/media/doc/DdDeleteDirectDrawObject.txt

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+DdDeleteDirectDrawObject
+
+we need release directdraw handler the cache or not cache handler
+1. check see if DirectDrawGlobal->hDD is NULL or not
+
+2. if both cache directdraw handler and public handler is NULL
+   then we need return false, fail to release it or it was already release
+
+3. if public directdraw handler is not null we need release it 
+   and return if we susses or not. 
+
+4. we need check if we need rest the internal cache if public being release
+     
+
+use  NtGdiDdDeleteDirectDrawObject((HANDLE)DirectDrawGlobal->hDD); 
+to release a directdraw handler.