broken backwards compatibility

[Silvio Heinrich]

On 04/28/2011 03:17 PM, Cyrille Berger Skott wrote:
> On Thursday 28 April 2011, Boudewijn Rempt wrote:
>> I tried loading the Wasted Mutants showcase file in Krita today and
>> discovered that it doesn't look like the original version on krita.org
>> anymore... Maybe that's because the background gradient layer was
>> disabled, but I fear we have a regression here. Animtim, can you check?
> It is probably related to this unit test failure:
> http://my.cdash.org/testDetails.php?test=5883333&build=182488
>
> Since the file use the "screen" Composite op which now return totally different
> values:
> FAIL!  : TestKoCompositeOps::testCompositeScreen() Compared values are not the
> same
>     Actual (p16f1.red): 15014
>     Expected ((quint16)18840): 18840
>     Loc:
> [/home/cyrille/src/calligra/libs/pigment/tests/TestKoCompositeOps.cpp(1072)]
>
>
> And if you click on the "Alpha channel" icon for layer "21" then the file is
> fixed.
>
> My opinion is that the default value for "Alpha channel" should be inversed.
> Especially since it would give the same behaviour as in other applications.
You cannot easily inverse this behavior. This will inverse the Over 
(Normal) blending mode, too.
Then you have for every layer the "Atop" blending mode behavior as default.
Then we would need to make a special case for the Over mode. That brings 
only inconsistencies in the system and
I think it's pretty consistent and logical right now since it's working 
like the alpha locking just for layer compositing.
But there is an other possibility... I don't know if there is a version 
number saved in the *.kra files.
We could simply make a special case for the *.kra files < 2.4 and invert 
the alpha flag for all layers that are not using the Over mode
when loading the file.