mlib plugin question

mlib plugin question

[Peter Rolf]

Hi,

I use a mlib plugin to manually start/stop transparency. All graphics
in between will be drawn with the defined state. Not very useful in
general, but I need it for some graphics in Aero.

This is the simple code..

MP side:

def btransp(expr a, t) =
    draw origin withprescript "mtr_transp=start"
        withprescript "mtr_alternative=" & decimal a
        withprescript "mtr_transparency=" & decimal t  ;
enddef ;

def etransp =
    draw origin withprescript "mtr_transp=stop" ;
enddef ;


TEX side:

local function mtr_process(object,prescript,before,after)
    local mtr_alternative = prescript.mtr_alternative
    if prescript.mtr_transp == "start" then
        if mtr_alternative then
            mtr_alternative = tonumber(mtr_alternative)
            local mtr_transparency = tonumber(prescript.mtr_transparency)
            before[#before+1] = format("q /Tr%s gs %%
mtr",registertransparency(nil,mtr_alternative,mtr_transparency,true))
        end
    elseif prescript.mtr_transp == "stop" then
        after[#after+1] = "Q % mtr"
    else
        -- fatal error
    end
--    object.path = true -- 'true' gives runtime error, 'false' distorts
content
    object.grouped = true
    object.type = false -- don't draw
    object.color = false
end

Usage:

btransp(normaltransparency,.5);
<whatever>
etransp;


This works so far (no visible artefacts), but part of the 'draw origin'
is (although not drawn) still existent in the code.

[..]
q /Tr1 gs % mtr
10.000000 M % unwanted setup for 'origin'
1 j
1 J
0.500000 w
0.000000 0.000000 m
0.000000 0.000000 l

<whatever>

10.000000 M % unwanted setup for 'origin'
1 j
1 J
0.500000 w
0.000000 0.000000 m
0.000000 0.000000 l
Q % mtr
[..]

I had a solution for the old 'specials', but I can't find one for the
plugin handler. How can I get rid of the 'trigger code'?


Peter
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___________________________________________________________________________________

Re: mlib plugin question

[Hans Hagen]

On 10-8-2011 8:00, Peter Rolf wrote:

> Usage:
>
> btransp(normaltransparency,.5);
> <whatever>
> etransp;

Officially

   draw image ( whatever ) withtransparency (normaltransparency,.5)

should work, but there is a (known) bug in mplib with respect to 
applying scripts to the components of a picture (color works ok).

> I had a solution for the old 'specials', but I can't find one for the
> plugin handler. How can I get rid of the 'trigger code'?

In this respect the converter is kind of black box and there is not 
something like a stack or disable options. Maybe some day but I'd rather 
not touch the code now.

Hans

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               Ridderstraat 27 | 8061 GH Hasselt | The Netherlands
     tel: 038 477 53 69 | voip: 087 875 68 74 | www.pragma-ade.com
                                              | www.pragma-pod.nl
-----------------------------------------------------------------
___________________________________________________________________________________
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
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archive  : http://foundry.supelec.fr/projects/contextrev/
wiki     : http://contextgarden.net
___________________________________________________________________________________

Re: mlib plugin question

[Peter Rolf]

Am 14.08.2011 19:47, schrieb Hans Hagen:
> On 10-8-2011 8:00, Peter Rolf wrote:
> 
>> Usage:
>>
>> btransp(normaltransparency,.5);
>> <whatever>
>> etransp;
> 
> Officially
> 
>   draw image ( whatever ) withtransparency (normaltransparency,.5)
> 
> should work, but there is a (known) bug in mplib with respect to
> applying scripts to the components of a picture (color works ok).
>
The problem with the current transparency implementation is, that it
doesn't use a transparency stack. If you use nested transparency,
switching back to non transparent (/Tr0) is not what you always want.
That's the only reason for this extra (ugly) plugin.

>> I had a solution for the old 'specials', but I can't find one for the
>> plugin handler. How can I get rid of the 'trigger code'?
> 
> In this respect the converter is kind of black box and there is not
> something like a stack or disable options. Maybe some day but I'd rather
> not touch the code now.
>
OK. I think I found a solution in the meantime (but still to be tested).

Thanks for taking the time.

Peter
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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/
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___________________________________________________________________________________

Re: mlib plugin question

[Peter Rolf]

Just for the records (or for the masses of mlib plugin
programmers/lovers out there)... ;-)

Am 10.08.2011 20:00, schrieb Peter Rolf:
> Hi,
> 
> I use a mlib plugin to manually start/stop transparency. All graphics
> in between will be drawn with the defined state. Not very useful in
> general, but I need it for some graphics in Aero.
> 
> This is the simple code..
> 
> MP side:
> 
> def btransp(expr a, t) =
>     draw origin withprescript "mtr_transp=start"
>         withprescript "mtr_alternative=" & decimal a
>         withprescript "mtr_transparency=" & decimal t  ;
> enddef ;
> 
> def etransp =
>     draw origin withprescript "mtr_transp=stop" ;
> enddef ;
> 
> 
> TEX side:
> 
> local function mtr_process(object,prescript,before,after)
>     local mtr_alternative = prescript.mtr_alternative
>     if prescript.mtr_transp == "start" then
>         if mtr_alternative then
>             mtr_alternative = tonumber(mtr_alternative)
>             local mtr_transparency = tonumber(prescript.mtr_transparency)
>             before[#before+1] = format("q /Tr%s gs %%
> mtr",registertransparency(nil,mtr_alternative,mtr_transparency,true))
>         end
>     elseif prescript.mtr_transp == "stop" then
>         after[#after+1] = "Q % mtr"
>     else
>         -- fatal error
>     end
> --    object.path = true -- 'true' gives runtime error, 'false' distorts
> content
>     object.grouped = true
>     object.type = false -- don't draw
>     object.color = false
> end
>

local function mtr_process(object,prescript,before,after)
    local mtr_alternative = prescript.mtr_alternative
    if prescript.mtr_transp == "start" then
        if mtr_alternative then
            mtr_alternative = tonumber(mtr_alternative)
            local mtr_transparency = tonumber(prescript.mtr_transparency)
            before[#before+1] = format("q /Tr%s gs %%
mtr",registertransparency(nil,mtr_alternative,mtr_transparency,true))
        end
    elseif prescript.mtr_transp == "stop" then
        after[#after+1] = "Q % mtr"
    else
        -- fatal error
    end
    -- get rid of the 'draw <whatever> ...' trigger code
    object.type = "mtr-plugin" -- don't use an existing type
    object.path = false -- ignore path from 'draw <whatever>' trigger code
    object.grouped = false -- no additional 'miterlimit, linejoin,
linecap' for grouping
    object.miterlimit, object.linejoin, object.linecap = -1,-1,-1 -- use
default values, so a setting is unnecessary
    object.pen = false -- don't set pen line width
    object.color = false
end

> Usage:
> 
> btransp(normaltransparency,.5);
> <whatever>
> etransp;
> 
> 
> This works so far (no visible artefacts), but part of the 'draw origin'
> is (although not drawn) still existent in the code.
> 
> [..]
> q /Tr1 gs % mtr
> 10.000000 M % unwanted setup for 'origin'
> 1 j
> 1 J
> 0.500000 w
> 0.000000 0.000000 m
> 0.000000 0.000000 l
> 
> <whatever>
> 
> 10.000000 M % unwanted setup for 'origin'
> 1 j
> 1 J
> 0.500000 w
> 0.000000 0.000000 m
> 0.000000 0.000000 l
> Q % mtr
> [..]
> 
> I had a solution for the old 'specials', but I can't find one for the
> plugin handler. How can I get rid of the 'trigger code'?
> 
> 
> Peter
> ___________________________________________________________________________________
> 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
> ___________________________________________________________________________________
> 

___________________________________________________________________________________
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
___________________________________________________________________________________