Some thoughts about the ominous DIB Engine
r.kalbermatter at hccnet.nl
Fri Feb 9 04:41:19 CST 2007
I have been following this discussion for quite some time and finally
decided to look into it a little bit. While the Wiki mentions that a
difficult part of this would be to get any design accepted by Alexandre it
does absolutely not say in any way what kind of approach would be likely to
be accepted, other than it needs to be in small incremental steps.
I must admit that I haven't entirely looked through the whole Wine tree yet
so I might be missing something but from the old Transgaming patch and some
investigation into GDI32 I would see two principal aproaches to add such an
interface to Wine.
1) Like in the Transgaming patch hook into winex11.drv where apropriate.
2) Add the dib engine as a dibdrv into GDI32 directly similar to what has
been done for enhmfdrv and mfdrv already.
Obviously 1) has been tried and seemed to work in some ways eventhough there
would still need to be quite some more work to be done. What I don't like
about this aproach is that conceptually it seems to add this functionality
at the wrong end. If there is ever going to be another display driver than
winex11.drv all the hooking would have to be done again and also adding new
GDI methods to the driver as development goes always requires also some
significant changes to winex11.drv.
Not sure if someone ever attempted 2) but IMHO it would place DIB handling
where it conceptually should be. The dibdrv function array could be added as
extra field to the private DIB data structure and initialized on DIB
creation. On non existing DIB methods (NULL pointer) the operation would be
simply sent to the display driver as is done now. I believe this could be
generalized enough to make it a single time change, with new dibdrv methods
getting then available whenever implemented in small incremental patches.
Possible problems I could see are however synchronizing with X (not sure if
that is really a possible problem as I do not understand X so far) and maybe
other drivers such as wine3d3.drv that seem to hook into winex11.drv too
(not sure if for DIB related operations).
This last one could however be gotten around by implementing the dibdrv as
loadable driver too, so that other drivers needing to use operations from it
could load it too.
I would like to hear comments of anyone that could add something to this and
maybe we can then add the result to the wiki page for further reference.
As it is now Wiki mostly says it is rather desirable, sort of hard to do and
the hardest part would be getting it into Wine at all. Maybe if there is a
more clear picture as to how it could be done and what is likely to have a
chance to pass Alexandre's critical eyes, there would be a bigger chance of
someone trying to get it finally started the right way.
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