Not following the conversation fully, but a practical solution may be
to use a small Python program that calls tesseract and print things
out to stdout.  Then OSProcess can handle it.On Thu, Nov 15, 2018 at
6:01 AM Edwin Ancaer <eancaer at gmail.com> wrote:
>
> Hello all,
>
> FFI was a little complexer than I had thought. And the Tesseract api was not helping either. But now I think I'm getting closer to make the example Ben proposed (https://github.com/tesseract-ocr/tesseract/wiki/APIExample, the C-program using the C-API) work in Squeak.
>
> Just one thing I cannot find an example for. I have to create the ExternalStructure classes for the structures PIXMAP and RGBA_QUAD. RGBA_QUAD is easy, but the PIXMAP-structure starts with an array of RGBA_QUADs.  RGBA_QUAD[] does not seem to be working as a type specification, and RGBA_SQUAD* will reserve place for the first element, but not the whole array. Is there an example for such structures?
>
> From the Header file:
>
> 00101 struct PixColormap
> 00102 {
> 00103     void            *array;     /* colormap table (array of RGBA_QUAD)     */
> 00104     l_int32          depth;     /* of pix (1, 2, 4 or 8 bpp)               */
> 00105     l_int32          nalloc;    /* number of color entries allocated       */
> 00106     l_int32          n;         /* number of color entries used            */
> 00107 };
> 00108 typedef struct PixColormap  PIXCMAP;
> 00109
> 00110
> 00111     /* Colormap table entry (after the BMP version).
> 00112      * Note that the BMP format stores the colormap table exactly
> 00113      * as it appears here, with color samples being stored sequentially,
> 00114      * in the order (b,g,r,a). */
> 00115 struct RGBA_Quad
> 00116 {
> 00117     l_uint8     blue;
> 00118     l_uint8     green;
> 00119     l_uint8     red;
> 00120     l_uint8     reserved;
> 00121 };
> 00122 typedef struct RGBA_Quad  RGBA_QUAD;
>
>
>
> Op zo 4 nov. 2018 om 06:15 schreef Kjell Godo <squeaklist at gmail.com>:
>>
>> Can i just write a simple C shared library or DLL which calls the C++ ? So you are repackaging the C++ as a C library? I can’t see how this tack could fail to work. Just repackage C++ as C.
>>
>> You would have to come up with a procedural less OOP-ish API i guess.  You could have C API functions F which take an Object as F’s first input and in this way each C++ Method becomes a C function. You only need wrap as much of the C++ API as you want to use and each C function just calls its C++ Method so making the wrappers is highly simple and mechanical i should think. it could even be automated. But i know some C++ but have never made anything in it.
>>
>> I suppose that if Smalltalk cannot contain a C++ Object then you could make a C struct which can be in Smalltalk and you have the API function copy this struct into the C++ Object then act on it then copy the Object data back into the struct which is in Smalltalk. But that’s a lot of work. Surely you can have a pointer to a C++ Object in Smalltalk.
>>
>> Maybe it would be better to have a separate C++ program P that you communicate with by sockets using Object handles H which are just Integer Array indexes into an Array of Objects in P? i suppose there could be a shared lib L that FFI could call which could call back program P if sockets were too slow or something.
>>
>> I guess Dolphin can  input a Smalltalk BlockClosure B into an FFI call to L which could input B into program P which could call B to get back into Dolphin but i haven’t tried it myself.
>>
>> I guess there is a Smalltalk interface to Python via a socket and then from Python to C++ is easy? Seems like a code generator that has all this stuff figured out could be good. I think VisualWorks is probably good at connecting to C++ via FFI. What about chicken scheme or any of the C based Schemes? What about Smalltalk/X?
>>
>> borgLisp is an idea to make multiple Lisp dialects each isomorphic to its target language like C or C++ or Python or Ruby or Prolog or java or C# or Scheme or Rust etc any language can have an isomorphic Lisp dialect targeting it in order to bind all the languages into a single borgLisp where you can mix and match all the languages together. Where each Lisp dialect is just a simple Lisp code generator. And so once all the languages are in Lisp then all the Lisp things can be used to mix and match all the languages together and using Nix to set up and configure everything so everything works together one click like. all the different languages. so they can all work together in an easy generative format. So every language becomes Lisp and Lisp becomes every language. Using code generation you could even make a Debugger in Lisp and Smalltalk which could source debug any language like the Smalltalk debugger does for Smalltalk.
>>
>> but i guess this is off the topic
>>
>> On Fri, Nov 2, 2018 at 06:07 Ben Coman <btc at openinworld.com> wrote:
>>>
>>>
>>>
>>> On Fri, 2 Nov 2018 at 18:44, Edwin Ancaer <eancaer at gmail.com> wrote:
>>>>
>>>> Hello list,
>>>>
>>>> As I'm looking at a way to automate the search of documents in my humble administration, I read some articles about OCR. I came along an article about using Python with Tesseract, to transform an scan of a document into text, that is searchable.
>>>>
>>>> My question now is if I can do something similar with Squeak. To my inexperienced eye, it seems like I should use FFI to call the functions in the Tesseract API, but this API is in  C++, and I don't know if it is possible to use FFI to call C++ functions?
>>>
>>>
>>> You are right C++ is difficult because of the name mangling of function symbols,
>>> but good fortune I notice Tesseract has C bindings...
>>>     https://github.com/tesseract-ocr/tesseract#for-developers
>>>     https://github.com/tesseract-ocr/tesseract/blob/master/src/api/capi.h
>>> so it looks like you are in the clear.
>>>
>>>
>>>> Or should I forget the API and use OSProcess to start the tesseract program?
>>>
>>>
>>> FFI will be more flexible.
>>>
>>>
>>>> Could anyone point me in the right direction, or just tell  if the whole idea is insane?
>>>
>>>
>>> I think its a great idea and actually Tesseract FFI is something I've wanted to play with before but not had the time.
>>> I'd be interested to hear how you go with it.
>>>
>>> cheers -ben
>>>
>> 1q
>
>


--
-- Yoshiki