[Bug] Bug in BitBlt (rgbMin and other set alpha to 0)

>
> Hi Folks,
>
> I found a bug in BitBlt. The following rules:
>  20    rgbAdd:with:
>  21    rgbSub:with:
>  27    rgbMax:with
>  28    rgbMin:with:
>  29    rgbMinInvert:with:
>  37    rgbMul:with:
> will set alpha = 0 if the destination is 32 bit deep. This means that if
> the destination is 32bpp, these rules are useless, as they will ignore
> source and destination and always set all the pixels to transparent.
>
> To test, try printing:
>    f1 := Form extent: 8@8 depth: 32.
>    f1 fillColor: (Color r: 1.0 g: 1.0 b: 0.7 alpha: 0.6).
>    f2 := Form extent: 8@8 depth: 32.
>    f2 fillColor: (Color r: 0.5 g: 1.0 b: 0.7 alpha: 0.7).
>    bb :=(BitBlt toForm: f1) sourceForm: f2; combinationRule: 28; copyBits.
>    (f1 colorAt: 2@2) alpha
>
> The fix I propose is in the last line of all those methods, to change
> 'nBits: 8 nPartitions: 3' to read 'nBits: 8 nPartitions: 4'. This would
> make all these operations to treat alpha as they treat red, green and
> blue. This could have some performance impact. Reasonable alternatives
> includes leaving alpha unchanged, set it to 255 (opaque), or set it to
> (source max: destination).
>
> What do you think?
>
> Thanks,
> Juan Vuletich
>

>
> Andreas Raab wrote:
> >
> >Juan Vuletich wrote:
> >>Can you advice on the steps for this fix to get into the precompiled
> >>VMs? This is my first contribution to the VM since the end of the SqC
> >>days...
> >
> >Get it into VMMaker and then lobby for an update. David has been the
> >front-man for integration lately so you might want to ping him.
> >
> Let's try. Tim are you there? You're the maintainer of VMMaker right?

>
> Juan,
>
> I'm helping out in Tim's (hopefully temporary) absence. If you can send
> a change set to this list, I'll add it to VMMaker on SqueakSource. If
> you can also open a Mantis issue to keep a record of the issue, that
> would be even better. There is a "VM" bug category on Mantis (bugs.squeak.org)
> for things like this.
>
> Thanks,
>
> Dave
>  

>  
> On Wed, Apr 01, 2009 at 09:12:15AM -0300, Juan Vuletich wrote:
>  
>> I added #7327 to Mantis, and I attached the fix too.
>>    
>
> Thanks Juan,
>
> I will pull this into VMMaker as soon as I can. I'm having some
> internet/ISP problems at the moment so it may take me a day or
> so until I can reconnect with SqueakSource et al.
>
> Dave
>  

>
> David T. Lewis wrote:
> >
> >On Wed, Apr 01, 2009 at 09:12:15AM -0300, Juan Vuletich wrote:
> >  
> >>I added #7327 to Mantis, and I attached the fix too.
> >>    
> >
> >Thanks Juan,
> >
> >I will pull this into VMMaker as soon as I can. I'm having some
> >internet/ISP problems at the moment so it may take me a day or
> >so until I can reconnect with SqueakSource et al.
> >
> >Dave
> >  
> Thanks David!

>  
> On Thu, Apr 02, 2009 at 10:03:46AM -0300, Juan Vuletich wrote:
>  
>> David T. Lewis wrote:
>>    
>>> On Wed, Apr 01, 2009 at 09:12:15AM -0300, Juan Vuletich wrote:
>>>  
>>>      
>>>> I added #7327 to Mantis, and I attached the fix too.
>>>>    
>>>>        
>>> Thanks Juan,
>>>
>>> I will pull this into VMMaker as soon as I can. I'm having some
>>> internet/ISP problems at the moment so it may take me a day or
>>> so until I can reconnect with SqueakSource et al.
>>>
>>> Dave
>>>  
>>>      
>> Thanks David!
>>    
>
> This is in VMMaker-dtl.119 on SqueakSource. I set Mantis #7327 status
> to "resolved".
>
> Juan, just for the record, can you please confirm that your contributions
> to VMMaker are released under MIT license? ...just in case somebody starts
> asking about it five years from now ;)
>
> Thanks a lot,
>
> Dave
>  

>
> > Juan, just for the record, can you please confirm that your contributions
> > to VMMaker are released under MIT license? ...just in case somebody starts
> > asking about it five years from now ;)
> >
> > Thanks a lot,
> >
> > Dave
> >  
> I signed the Viewpoints agreement. I believe it covers both past and
> future contributions. If not, this is my statement:
>
> All my contributions to VMMaker and the rest of Squeak, both past and
> future, are (or will be) released under the MIT license.

>  
> At Thu, 02 Apr 2009 10:22:00 -0300,
> Juan Vuletich wrote:
>  
>>> Juan, just for the record, can you please confirm that your contributions
>>> to VMMaker are released under MIT license? ...just in case somebody starts
>>> asking about it five years from now ;)
>>>
>>> Thanks a lot,
>>>
>>> Dave
>>>  
>>>      
>> I signed the Viewpoints agreement. I believe it covers both past and
>> future contributions. If not, this is my statement:
>>
>> All my contributions to VMMaker and the rest of Squeak, both past and
>> future, are (or will be) released under the MIT license.
>>    
>
>   The Viewpoints agreement covers the past contribution made under
> the Squeak License, but a clear statement like this (and perhaps a
> clearer one on your website) would be good.
>
> -- Yoshiki

>
> >   The Viewpoints agreement covers the past contribution made under
> > the Squeak License, but a clear statement like this (and perhaps a
> > clearer one on your website) would be good.
> >
> > -- Yoshiki
> Why "would be good" and not "is good"? What is missing?
>
> The Cuis image (the most significant code I published since I signed the
> agreement) is under the MIT license (thanks to you Yoshiki!). It
> includes a workspace with a clear statement.

>  
> At Mon, 06 Apr 2009 22:20:35 -0300,
> Juan Vuletich wrote:
>  
>>>   The Viewpoints agreement covers the past contribution made under
>>> the Squeak License, but a clear statement like this (and perhaps a
>>> clearer one on your website) would be good.
>>>
>>> -- Yoshiki
>>>      
>> Why "would be good" and not "is good"? What is missing?
>>
>> The Cuis image (the most significant code I published since I signed the
>> agreement) is under the MIT license (thanks to you Yoshiki!). It
>> includes a workspace with a clear statement.
>>    
>
>   Sorry for writing an obscure message.  What I meant was more about a
> blurb on your website.
>
>  
>> I will include a general statement in my site covering any code found there.
>>
>> Is there anything else you believe I should do?
>>    
>
>   That should be enough.  I downloaded a version played with it but
> now cannot tell a license file was in the .zip file or not.  It is
> good to have it in there, too.
>
> -- Yoshiki