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alpha trasparent windows crash on MOS 16bit...

Posted: Fri Jan 20, 2012 11:07 pm
by Tuxedo
Hi!
I'm using a trasparent window in LoViewThumb to show image infos and it works pretty good on 24bit screens, on 16 bit screens under AmigaOS4.x the window was simply not trasparent, but on MOS 2.7 Hollywood crash and complain about alpha trasparent windows cant work...
That was correct or was a bug? I ask it since on AmigaOS4.1 simply the window was not trasparent and all workls fine...

Thank you!

Re: alpha trasparent windows crash on MOS 16bit...

Posted: Sat Jan 21, 2012 11:36 am
by airsoftsoftwair
That's normal behaviour. On 16-bit screens there's obviously no room for any alpha channel information because you only have 5 bits red, 6 bits green and 5 bits of blue. By the way, please do not use the verb "crash" when Hollywood exits cleanly with an error message. That's not a crash, it's a clean exit because something went wrong. A crash means that Hollywood throws a system exception, freezes your system or leads to a reboot etc. Such crashes are always bugs. But if Hollywood just shows a requester complaining about something and then exits cleanly, then that's definitely not a crash but a predefined way of exiting to prevent a crash :)

Re: alpha trasparent windows crash on MOS 16bit...

Posted: Sat Jan 21, 2012 1:19 pm
by Tuxedo
Ok,
not crash but clean exit, but however why that dont hanppen on AmigaOS4.1? Why simply Hollywood dont have the same (better) behaviour than on AmigaO4.1 also on MOS2.7 diaplaying a not trasparent window? OS limitaion?

Re: alpha trasparent windows crash on MOS 16bit...

Posted: Sat Jan 21, 2012 1:58 pm
by djrikki
Tux, morale of the story.. do not use anything less than a 32-bit screen. :lol:

The reasons too use anything less than 32-bit are so few they are not even worth considering.

Re: alpha trasparent windows crash on MOS 16bit...

Posted: Sat Jan 21, 2012 2:19 pm
by Tuxedo
yes but since on OS4.1 it works why dont works also on MOS? Some users uses 16bit screen to save video memory(like MacMini or Sam440ep users)...

Re: alpha trasparent windows crash on MOS 16bit...

Posted: Sat Jan 21, 2012 4:31 pm
by airsoftsoftwair
It's implementation dependent. AFAIR OS4 has the alpha transparency feature implemented in its layers.library while on MorphOS it's dependent on the screen bitmap directly. That's why it's impossible to use alpha transparency on anything but 32-bit modes in MorphOS.

Re: alpha trasparent windows crash on MOS 16bit...

Posted: Sat Jan 21, 2012 4:46 pm
by Tuxedo
Ok,
so I've to check if the current screen was 16bit to use or not display transparency...but how? In GetAttribute() command I dont found anything regarding host screen type...

Re: alpha trasparent windows crash on MOS 16bit...

Posted: Tue Feb 21, 2012 12:21 pm
by fingus
You MUST enable Compositing under AmigaOS4.1 so that transparency works on 16Bit Workbench!

And this only works if you handle it with BGPIC!

Re: alpha trasparent windows crash on MOS 16bit...

Posted: Thu Dec 14, 2017 6:06 pm
by jPV
Hmmdi... I noticed now that MorphOS hangs when trying to run alpha transparent windows on 16bit screens. I haven't got logs yet, because almost everything freezes, even though mouse pointer moves, but can't do much anything else. I've tried several times with the AlphaApple example.

Re: alpha trasparent windows crash on MOS 16bit...

Posted: Fri Dec 15, 2017 11:10 pm
by airsoftsoftwair
Confirmed. Will be fixed.