[directfb-dev] Re: [directfb-users] Re: Brightening surfaces

[Denis Oliver Kropp <dok@directfb.org>]

Quoting Hallvar Helleseth (hallvar@ii.uib.no):
> Confirmed :) However. Either the generic driver or matrox driver has a
> bug here somewhere.
> When Filling rectangle with an alphachannel onto a surface.
> With generic driver: the whole surface gets that alpha transparency.
> With matrox  driver: the rectangle gets blended onto the surface with
>                      the surface keeping the alphachannel it had before.
> 
> IMHO the matrox driver does the expected and wanted behavior.

The Matrox driver activates a feature called VIDEOALPHA which
saturates the alpha channel so that it won't be less opaque than before.

In general the rendering shouldn't be different with hardware or
software rendering. I have to look into that more and check how
the new premultiply/demultiply stages are related to it.

-- 
Best regards,
  Denis Oliver Kropp

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