transparency problem (mkiv)

transparency problem (mkiv)

[Peter Rolf]

Hi,

I noticed some problems with transparency colors lately. But every time
I tried to make a minimal example out of it, the code worked. Now, by
chance, I found a not working example.


\setuppagenumber[state=stop]
\definecolor[tcolor][r=1,a=1,t=.6]

\definetextbackground[ghost]
  [background=color,backgroundcolor=tcolor]

\starttext

\starttextbackground[ghost]
FOO
\stoptextbackground

\stoptext


Here the error message...

metapost        > terminal: >> (redpart boxfillcolor,greenpart
boxfillcolor,bluepart boxfillcolor)
>> 1
! Equation cannot be performed (color=numeric).
<to be read again>
                   withprescript
transparent->1withprescript

"tr_alternative="&decimal.transparency_alternativ...
<*> ... boxfillcolor := transparent(1,0.6,(1,0,0))
                                                   ; boxfilloffset :=
0.0pt ...

! Extra tokens will be flushed.


Regards, Peter
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Re: transparency problem (mkiv)

[Hans Hagen]

On 5-9-2011 14:36, Peter Rolf wrote:
> Hi,
>
> I noticed some problems with transparency colors lately. But every time
> I tried to make a minimal example out of it, the code worked. Now, by
> chance, I found a not working example.
>
>
> \setuppagenumber[state=stop]
> \definecolor[tcolor][r=1,a=1,t=.6]
>
> \definetextbackground[ghost]
>    [background=color,backgroundcolor=tcolor]
>
> \starttext
>
> \starttextbackground[ghost]
> FOO
> \stoptextbackground
>
> \stoptext
>
>
> Here the error message...
>
> metapost>  terminal:>>  (redpart boxfillcolor,greenpart
> boxfillcolor,bluepart boxfillcolor)
>>> 1
> ! Equation cannot be performed (color=numeric).
> <to be read again>
>                     withprescript
> transparent->1withprescript
>
> "tr_alternative="&decimal.transparency_alternativ...
> <*>  ... boxfillcolor := transparent(1,0.6,(1,0,0))
>                                                     ; boxfilloffset :=
> 0.0pt ...
>
> ! Extra tokens will be flushed.

This is a side effect of no longer using the ugly color hackery on the 
one hand (using scripts instead) and mp having 3 color related data 
types that don't carry scripts themselves.

This means that we cannot assign colors (with transparencies) reliable. 
I made a patch (at the mp macro level) for the backgrounds but more 
placed might need patching. So, from now on we will also have different 
files for mp: mpii and mpiv.

I uploaded a beta, so best do some testing right away as i might have 
messed up,

Hans

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___________________________________________________________________________________
If your question is of interest to others as well, please add an entry to the Wiki!

maillist : ntg-context@ntg.nl / http://www.ntg.nl/mailman/listinfo/ntg-context
webpage  : http://www.pragma-ade.nl / http://tex.aanhet.net
archive  : http://foundry.supelec.fr/projects/contextrev/
wiki     : http://contextgarden.net
___________________________________________________________________________________