ddraw correctness fixes patch

[Tony Lambregts]

Matthew Mastracci wrote:
> Thanks for the review - comments inline.
> 
> Christian Costa wrote:
> 
>>> The new locking mechanism is wrong. DDLOCK_xxx are just used for 
>>> optimization.
>>>
>>> The thing to do during the blit should be something like that :
>>>
>>> sdesc.dwSize = sizeof(sdesc);
>>> ddesc.dwSize = sizeof(ddesc);
>>> if (src == NULL)
>>> IDirectDrawSurface7_Lock(iface, &lock_dst, &ddesc, DDLOCK_WRITEONLY, 0);
>>> else if (src == iface) {
>>> RECT lock_union = < rect that just contains lock_dst and lock_src >; 
>>> IDirectDrawSurface7_Lock(iface, &lock_union, &ddesc, 0, 0);
>>> sdesc = ddesc;
>>
>>
>>
>> I think here that sdesc and ddesc surface pointers should be remapped 
>> according to lock_src and lock_dest.
> 
> 
> The above logic makes sense - I originally tried to solve it this way, 
> but ended up failing because of the sdesc and ddesc mapping issue.  Any 
> idea how to do this cleanly?

I think what will work is IntersectRect() from windows/rect.c

IntersectRect( LPRECT dest, const RECT *src1, const RECT *src2)

Something like the following perhaps?

RECT lock_union

if IntersectRect(&lockunion, &sdesc, &ddesc)
     IDirectDrawSurface7_Lock(iface, &lock_union, &ddesc, 0, 0);
....


--

Tony Lambregts