[Bug 3902] Unnormal slowness in Heroes 4 (X11DRV_BitBlt?)

[Wine Bugs]

http://bugs.winehq.org/show_bug.cgi?id=3902

------- Additional Comments From [e-mail]  2005-30-11 09:48 -------
I came to the conclusion that the slowness in "Heroes IV" it has to do with 
sync'ing lage bitmaps between application DIBs and X Server(see the above log).
This happens when a GDI call tries to get a DIB from 'DIB_Status_AppMod' stat 
into 'DIB_Status_GdiMod' stat. Eventually X11DRV_DIB_DoUpdateDIBSection() will 
be called, which will try to sync the entire bitmap, even though maybe only a 
small part of the bitmap has been modified by the program:

static void X11DRV_DIB_DoUpdateDIBSection(X_PHYSBITMAP *physBitmap, BOOL toDIB)
{
     BITMAP bitmap;

GetObjectW( physBitmap->hbitmap, sizeof(bitmap), &bitmap );
     X11DRV_DIB_DoCopyDIBSection(physBitmap, toDIB,
                                 physBitmap->colorMap, physBitmap->nColorMap,
                                 physBitmap->pixmap, 0, 0, 0, 0,
                                 bitmap.bmWidth, bitmap.bmHeight);
}

I think this can be improved in the following way:

1. Add a new member to X_PHYSBITMAP structure (RECT LastModRect) which will 
memorise the acctual rectangle that needs to be sync'ed by 
X11DRV_DIB_DoCopyDIBSection() function.

2. Modify all or a number or GDI function to set physBitmap->LastModRect 
accordingly, before calling X11DRV_DIB_Coerce(physBitmap, DIB_Status_GdiMod, 
FALSE).

3. Modify X11DRV_DIB_DoUpdateDIBSection() to take in consideration LastModRect 
and if its valid, try sync only that part of the bitmap and afterwords 
invalidate LastModRect. If LastModRect doesn't contain valid values, 
X11DRV_DIB_DoUpdateDIBSection() will try to sync the entire bitmap as it did 
untill now, this way, if a GDI function doesn't set LastModRect accordingly, 
everything will still work.

If anybody else has any other ideea how to improve performance, please share 
it :)