[NTG-context] runtime problem with metafun() code

Peter Rolf indiego at gmx.net
Mon Jan 27 14:17:18 CET 2014


Am 27.01.2014 13:12, schrieb Hans Hagen:
> On 1/25/2014 1:58 PM, Peter Rolf wrote:
>> 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?
> 
> 
> function drops.foo(id,width,height,radius)
>     drops.generate_default_path(id,width,height,radius)
>     context(function() inspect(metapost.variables) end) -- empty here
> end
> 
> or
> 
> function drops.bar()
>     inspect(metapost.variables)
> end
> 
> function drops.foo(id,width,height,radius)
>     drops.generate_default_path(id,width,height,radius)
>     context(drops.bar) -- empty here
> end
> 
> 
Ah, that's how it works. I'm still a luatex noob...
Many thanks, Hans!!


Peter




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