Re: runtime problem with metafun() code

[Peter Rolf <indiego@gmx.net>]

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Am 25.01.2014 01:07, schrieb Hans Hagen:
> On 1/24/2014 7:41 PM, Peter Rolf wrote:
>> Am 24.01.2014 14:45, schrieb Hans Hagen:
>>> On 1/24/2014 1:35 PM, Peter Rolf wrote:
>>>> Hi,
>>>>
>>>> I try to create a Metapost path in lua and it works so far for the
>>>> attached example. But a call of that function from another lua function
>>>> sadly fails (no path visible after call). The code seems to be executed
>>>> later (the output from 'show pid;' appears somewhere later in the log).
>>>>
>>>> How can I ensure that the code is executed at runtime?
>>>
>>> I don't understand the issue but isn't there a
>>>
>>>      metafun("draw p;")
>>>
>>> missing then?
>>>
>> Setting the bounding box has the same effect, as drawing something.
>> Both methods avoid that the emtpy graphic is ignored by ConTeXt.
>>
>> Anyhow, the MP path is not available in metapost.variables after the
>> function call. If there is no other way I have to call the function from
>> the TeX side (like in the attached example). Will look into that
>> tomorrow.
> 
> %D We also provide an outputless run:
> 
> \unexpanded\def\startMPcalculation
>
I tried that command, but couldn't get it to work on the lua side.

The first pure MP line after context.startMPcalculation() raises a lua
error and a combination with metafun() is also not working. So how to
use this in lua?


Anyhow, the problem is the execution time of the MP graphic. I changed
the attached example a bit, so that you can see it.
The inspect() in drops.foo() gives an empty table, while the second
inspect on the TeX side shows the path "drops:foo".

I need the path right after the call (it needs to be adapted to IM
afterwards; mainly scaling and shifting). Is there a way to "force" the
execution of the graphic without switching back to the TeX side?


Peter



[-- Attachment #2: mplua.lua --]
[-- Type: text/x-lua, Size: 1310 bytes --]

thirddata            = thirddata            or { }
thirddata.drops      = thirddata.drops      or { }

local drops = thirddata.drops

local metafun = context.metafun

local format,todimen = string.format, string.todimen
local floor = math.floor

-- http://lua-users.org/wiki/SimpleRound
local function round(num, idp)
    local mult = 10^(idp or 0)
    return floor(num * mult + 0.5) / mult
end

function drops.numberofpixels(n,idp)
    local dimenfactor = 1/tex.pdfpxdimen
    return round(todimen(n)*dimenfactor,idp)
end

local numberofpixels = drops.numberofpixels


function drops.generate_default_path(id,width,height,radius)

    local w,h,r
    w = numberofpixels(width); h = numberofpixels(height); r = numberofpixels(radius)

    metafun.start()

    metafun("save p,pid; path p; string pid;")

    -- metafun("id := \"drops:boxshadow_w%sh%sr%s\";",w,h,r)
    metafun("pid := \"%s\";",id)
    --metafun("show pid;") -- ok
    metafun("p:= unitsquare xyscaled(%s,%s) smoothed %s;",w,h,r)

    metafun("passvariable(pid,p);")
    metafun("setbounds currentpicture to boundingbox(p);") -- 'activator'; void graphics are ignored

    metafun.stop()

end


function drops.foo(id,width,height,radius)
    drops.generate_default_path(id,width,height,radius)
    inspect(metapost.variables) -- empty here
end

[-- Attachment #3: mplua.mkiv --]
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\ctxloadluafile{mplua}{}


\starttext
\ctxlua{metapost.showlog = true}

%\ctxlua{thirddata.drops.generate_default_path("drops:boxshadow-w199h100r10","200pt","100pt","10pt")}
%\ctxlua{inspect(metapost.variables)}

\ctxlua{thirddata.drops.foo("drops:foo","200pt","100pt","10pt")}
\ctxlua{inspect(metapost.variables)} % ok here


\stoptext

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