[Vm-dev] pb with primitive #primitiveScreenDepth on Linux ?

Christophe Demarey christophe.demarey at inria.fr
Thu Feb 2 09:44:52 UTC 2017

Hello Bert,

> Le 31 janv. 2017 à 18:18, Bert Freudenberg <bert at freudenbergs.de> a écrit :
> On Tue, Jan 31, 2017 at 10:44 AM, Christophe Demarey <christophe.demarey at inria.fr <mailto:christophe.demarey at inria.fr>> wrote:
> Hello,
> With Pavel, we discovered a strange behavior of the primitive #primitiveScreenDepth on Linux. It returns a value of 24 bits per pixel (True colors) that looks valid but not supported (at least by Pharo).
> DisplayScreen actualScreenDepth "(calling the primitive screenDepth)"
>         => 32 on OS X [OK]
>         => 24 on Linux [KO]
> Also, it is not consistent with the primitive 91
> DisplayScreen new supportsDisplayDepth: DisplayScreen actualScreenDepth
>         => true on OS X
>         => false on Linux
> There are some safeguard image-side but it would be great if someone could check that vm side.
> That seems wrong indeed, since BitBlt can only handle power-of-two depths currently. It should answer 32 or -32 in this case. 
> Actually ... is there a difference in pixel layout for 32 bit MSB vs LSB forms? A quick test in SqueakJS suggests there isn’t.

I do not get what you mean by 32 bits MSB vs LSB form. Could you give an example of what to test?
If you mean a difference between depth 32 or -32, I do not see any difference.


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